Journal ofAffectiL,e Disorders, 22 (1991) 135-148

0 1991 Elsevier
ADONIS

SciencePublishers

135

B.V. 0165.0327/91/$03.50

0165032791001013

JAD 00814

Distinguishing psychotic and non-psychotic melancholia
GordonParker,Dusan Hadzi-Pavlovic,
Ian Hickie, Philip Boyce, Philip Mitchell,
Kay Wilhelm and Hem-y Brodaty

M ood Disorders Unit, School of Psychiatry, lJnir,ersity of New South W ales and DiLGion of Psychiatry, Prince Henry Hospital,
Sydney, Australia(Received 19 February 1991)(Accepted 27 March 1991)

Summary
To examine the necessary and sufficient status of delusions and hallucinations
as clinical features ofpsychotic (delusional)
depression,
we studied a consecutive
sample of 137 patients meeting DSM-III,
RDC and our clinical criteria for endogenous
depression/melancholia,of whom 35 had delusions
and/orhallucinations,and represented
our putative‘psychotic
depressives’(PDs). The PDs were
contrasted
with the remaining‘endogenous
depressives’(the EDs), and an age- and sex-matchedsubsampleof the latter, the MEDs. Univariate
and multivariate
analyses of clinical features establishedthat, in addition to the presence of delusions and/or
hallucinations,the PDs could be distinguishedinparticularby severe psychomotor
disturbance,
as well as by sustained and unvarying depressive content,
the absence of any diurnal mood variation and by constipation.
Latent class analyses suggested that overt
psychotic features (such as delusions and hallucinations)were sufficient but not necessary for a subject tobe assigned to the ‘psychotic’ latent class, and a subsequent
chart review suggested that, in some PDs,
actual psychotic
featuresmay not be able to be elicited because
of severe psychomotorchange,suggestingthat clinical relianceon eliciting delusions
or hallucinations
may result in a numberof‘masked psychotic depressives’ escaping valid diagnosis.

Key words:

Psychotic

depression;

Endogenous

depression;

Introduction
The clinical definitionof psychotic (delusional)

and classificatory
statusdepression
remain un-

Address
for correspondence:
Professor
Psychiatry
Unit, Prince of Wales Hospital,
Australia.

GordonParker,Randwick2031,

Distinction

clear. In the late 1970s Minter and Mandel(1979)
suggested
that, in the United States, psychotic
depression
had ‘come to mean the same as “endogenous depression”
or to mean a depression ofsevereproportions,
usually
with endogenous
symptomatology,
not necessarily
with symptomsof psychosis’. As well, ‘psychotic’ and ‘endogenous’ depression
have been used as synonymous
terms by proponentsof the contrasting
unitary

136(e.g., Kendell,1976) and binary (Kiloh et al.,1972) views of depression
classification.
For otherauthors (e.g., Gelder et al., 1983), the presence of‘psychotic’ features such as delusions and/or
hallucinations
is required.
In most official classificatory
definitionsof thedisorder,psychotic
featuresand/ora variable
constructof ‘functional
impairment’figureprominently.
For instance,
DSM-IIIessentiallydefines psychotic depression
when major depression is present and accompaniedby ‘gross impairment in reality testing’ (evidenced
by delusions,hallucinations,or depressive
stupor). The RDC(Spitzer et al., 1978) system allows two subcategories: (i> ‘psychotic major depressive
disorder’(either ‘probable’or ‘definite’) when those withmajor depression
have delusions
or hallucinations, and (ii> ‘incapacitating
major depressive
disorder’ (either ‘probable’or ‘definite’) to describe a psychotic depressive category essentiallyon the basis of extreme
severity or functional
impairment.
The ICD-9 system requires,for anaffective psychosis, a severe disturbanceof mood,accompanied
by one or more of the following:‘delusions,
perplexity,
disturbed
attitude
to self,
disorderof perception
and behaviour’.
In the‘manic-depressive
psychosis, depressed type’ subgroup, ‘reduced activity’ or ‘restlessness
and agitation’ is described, while the ICD-9 system also
allows for a ‘reactive depressive psychosis’, clinically similar but at times with less diurnal variation in symptoms, and usually associatedwith a‘serious disturbanceof behaviour’such as a suicide attempt, and provoked by a major life stressor. DSM-IIIR
distinguishes
between severity andpsychosis
in subclassifying
major
depressive
episodes, having a ‘severe, without psychotic features’ subgroup, as well as subgroups with either
mood-congruent
or mood-incongruent
psychotic
features, and with the latter groups defined entirely by the existence of delusions and/or
hallucinations.
Thus, several classificatory
systems allow a diagnosis of psychotic depression
to be made on
the basis of a number of broad descriptive terms(e.g., delusions, disordered
perception,functional
impairment,
severe psychomotor
disturbance,anddisorderedbehaviour)which may be difficult tocategorise
as present or absent. Certainly,delu-

sional ideas, borderline
delusionsand severely
non-psychotic
dysfunctional
ideas may be particularly difficult, at times, to distinguishfrom oneanother.
Our study sought to define psychotic
depression
from non-psychotic
melancholia,
focussing on the utility of categorisation
being dependent on establishing‘psychotic’ features suchas delusions and hallucinations.
We have recently reviewed (Parker et al., 1991)
the publishedliterature
on psychotic/ delusional
depression,and noted a number of methodological issues, including varying definitions,as well as
frequent reliance on retrospective
reviews of caserecords, generally involving non-standardised
data
sets. That review failed to suggest any firm epidemiologicaldifferences
between ‘psychotic’ andcomparison
depressives
for age, age of initialonset, sex ratio, number of previous episodes ormorbid risk of major depression in relatives, apartfrom the psychotic
depressives
having an increased rate of bipolar disorderamongsttheir
relatives.
Clinically, the review suggested that psychotic
depressives
were more likely to have had delusional episodes in the past, with the delusional
themes often repeated.
The presence or greater
severity of psychomotorchange (agitation and/or
retardation)
was the most frequently
described
clinical feature, and there was evidence of a more
severe mood disturbance(with self-reproach
andguilt appearing
to be the most qualitatively
distinct mood symptoms).
Psychotic
subjects
appeared, however, to be no more likely to reportvegetative symptoms.
The view that psychotic depression
may be aseparate entity has been supported by the condition showing a poor response to antidepressantsalone. Spiker et al. (1985) summarised
a numberof studies to suggest that one-thirdof delusional
depressives
respond to a tricyclic antidepressantalone, one-halfto an antipsychotic
alone, andfour-fifths
to combination
antidepressant/antipsychotic drug therapy. Those authors noted thatthe efficacy of electroconvulsive
therapy (ECT) in
psychotic depression
appears comparable
to combination
drug therapy. Most ECT studies, however, have been uncontrolled,
so that the subjects
may have been selected on clinical factors favouring ECT response. A contrastingbias may emerge

137

from ECT being administeredafter a failure of(due to insufficient
clinical information),
our reference group in this report is 305 patients.
response to psychotropic
medication.
As psychotic and non-psychotic
depressive disorders show distinct
differential
treatment
reRating scales and interciew schedulesponses, their phenomenologicaldifferentiationis
As part of the initial assessment,
patients wereof key importance.
Following
an earlier study
requested
to complete the Zung depression
scale(Parker et al., 1990) of our sample, where we(1965), while depressive symptoms were assessed
provided
evidencesuggesting
discontinuity
beusing a semi-structured
interview, assessing both
tween ‘melancholic’and ‘non-melancholic’
disorthe nadir of the episode and currently with preders (be it severity- or category-based),
we now
determined
coding options. The psychiatrist compursue possible clinical subdivisionof the melanpleted the 21-item Hamilton(1967) rating scale,cholic subgroup.
We thus compare clinical feathe Newcastle
depression
index (Carney et al.,tures in patients with psychotic and non-psychotic1965) and our Core diagnostic system (Parker etexpressions ,of melancholia,
when the diagnosis ofal., 19901, which is essentiallya mentalstate‘psychotic’ has been made on the basis of delurating of current psychomotorchange, with Core
sions and/or
hallucinations
in a clinicallydescores having been shown to distinguishclinicallypressed patient. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
diagnosed‘melancholic’
depressions
from residual depressive disorders.
Methods zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
Subjects and assessment procedure

Defining patient groups

The sample was derived from 310 consecutively diagnosed
depressive
patients
assessed as
in-patientsor out-patientsof a specialized
Mood
Disorders Unit (MDU), after screening out thosewith any non-depressive
primary diagnosis suchas schizophrenia
or alcoholism
to ensure, as far
as possible, that the major diagnosis was one ofdepression.
Referral patterns,
assessment
procedures and diagnostic
rules are fully described
elsewhere (Brodaty et al., 1987). Following a detailed semi-structured
interviewby a research
psychiatrist(also responsible
for treatment),inwhich depressive symptoms and other details wereassessed, DSM-III,
RDC and clinical diagnoses(corresponding
to ICD-9 descriptions)were made.
As diagnostic
allocation
was based on symptom
data (assessed currently
and for the nadir of theepisode), from historical informationand current
mental state signs, and both during treatment
andat regular follow-up reviews, diagnoses were notnecessarily fixed over time. We had some patients
whose delusions
and/orhallucinations
had remitted by baseline
assessment
and, conversely,some who developed
such features after that assessment. Thus, in this report we provide episodediagnoses,with one psychiatrist(I.H.) reviewing
all files and all diagnostic
decisions. As episodediagnoses
could not be made for five subjects

Following
clarificationof episode diagnoses,
three subgroups were selected:(i) psy chotic depressices (PDs) who (a> met
DSM-III
criteria
for major
depression
withmelancholia
and psychosis,and (b) met RDC
criteria for definite endogenous
depression
andpsychosis, and (c) received a ‘clinical’ diagnosis of
psychotic depression, which, in effect, meant clinically evident
delusions
and/orhallucinations
during their depressive
episode (i.e., PDs satisfied all three criteria sets and, as a minimum, haddelusions
and/orhallucinations),
with the latter
accepted if there was unequivocal
evidence of adelusion(e.g., a convictionthat the food was
poisoned) or an hallucination.
Subjects with clinically judged over-valued
ideas (e.g., an inappropriate sense of guilt) were not allocatedto thepsychotic group;(ii> endogenous depresskles (EDs) who (a) met
DSM-III
criteria
for major
depression
withmelancholia,and (b) met RDC criteria for definite endogenous
depression
but who were not
psychotic, and Cc) received a ‘clinical’ diagnosis of
endogenous
depression,
which we defined by features such as pervasive
anhedonia,
vegetative
symptoms,
significant
observablemood disturbance and psychomotorchange without evident
delusions or hallucinations;

138(iii) a subset of the EDs (termed
were age- and sex-matchedwithensure that any difference
betweengroups was not age-determined.

MEDS) who
the PDs, tothe first two

Statistical analyses
Comparisons
betweengroups on categoricalclinical features
were performed
initially using
chi-square
tests, except for comparisonof thePDs and MEDs, when McNemar’s
test (Hays,
1963) for correlated
proportions
was substituted.
Being an exact test, based on the binomial distribution,
there is no statistic
to report for thelatter, and only the level of significanceis tabulated. Subsequently,
a row effects logit model(Agresti,1984) was used to determine
whethercore signs were more severe in any one group.
This model treats the ratings (here l-4) as ordinal and, if it fits, gives the odds of patients in one
diagnostic
category being rated as more severe
compared to those in another category.
Predicting caseness
Grantedthat we had a group of melancholicpatients,
with some who could be ‘true psychotics’, and the rest ‘true non-psychotics’,
then
two approaches
were pursued.
First, using a ‘top-down’ strategy, we made ourcriteria-based(i.e., DSM-III,
RDC and clinical)
diagnosis(presuming
for the momentthat theputative allocation
is a valid ‘gold standard’)
thecriterion
dependent
variable, with its mandatory
requirement
delusions and/or
hallucinations,andexamined
how well any delineatedvariablesetclassified the patients into the two ‘episode diagnosis’ contrastinggroups. To that end, logistic
regression was used to identify that combinationof dichotomous
independent
variablesthat best
reproduced
cases’ scores on the dichotomous
dependent
variable.
Logistic regression
was preferred to a discriminantfunction analysis, in thatit provides a superior estimate of the regression
coefficients
when the independent
variablesareeither categoricalor a mix of continuous
andcategorical.
The fit of the model to the data was assessedusing two differing methods. In the first method,
individual
instances that did not fit were identified using Pearson residuals
to check that dis-

crepancies
between predicted
and actual scoreson the dependent
variable were small and unsystematic. The second method examined how accurately the model assigned
cases to the formal
diagnostic groups by using the classification
table
and a cut-off of 0.5 on the predictedscore. It is
important
to note that even if the model fits wellby the first method, this does not mean that it
will necessarily
assign cases accuratelyby thesecond method (Hosmer and Lemeshow,1989).
The difference
between the two models can betested comparing
the change in deviance against
chi-square.
For individual
predictors,
approximate t values can be calculated.
All calculations
were done using the GLIM (1987) system.
Secondly, we used a ‘bottom-up’
strategy, nolongerassumingthat our criterion
diagnostic
measure was valid, but instead that psychotic andnon-psychotic
melancholia
were two putative‘classes’ awaiting formal definition by isolation of
those characteristics
best defining the two groups
or, at least, distinguishing
one group from theother. Latent class analysis (LCA) is an appropriate method
for assessing
manifest
categoricalvariables (i.e., presence/
absence of a clinical feature) in such a way. LCA gives the proportioninthe sample belonging to each class, and, for eachclass, the probabilityof a positive responsetoeach item by a member of that class. The LCA
groupings
and diagnosis
are competingmodelsand so, in the first instance at least, discrepancies
between the two are potentially informative pointsof contention
and not ‘failures’ of the LCA.
When using LCA to reduce items, we progressively deleted
those which had relativelyhighfalse positive or false negative rates. The procedure given by Bartholomew(1987) for fitting alatent class model and calculating standard errors
was written as a program in the GAUSS (Aptech
Systems, Inc., 1988) language. Very small probabilities cause numerical difficulties when calculating standard
errors, so these probabilities
were
adjusted slightly to overcome this difficulty. The
test for the number of classes (always 2 versus 1)
was as set out by Everitt (1988).
Examining predictice strength
As the performanceof a diagnostic
related directly to the cut-off used andtest isto the139base rate or prevalenceof the disorder in that
the EDs and MEDs to have received combination
sample, researchers
have been encouraged(e.g.,
antipsychotic/
antidepressant
medication
and/or
Hsiao et al., 1989) to examine the performanceof
ECT during a previous episode. For the present
tests using methods
like Receiver
Operatingepisode, treatment
for sample members was natuCurves (ROC). We chose to examine the effect ofralistic and dependent
upon clinical judgment.
changing the prevalence of the latent classes ‘psyMost PDs (91%) were admitted to hospital comchotic’ and ‘non-psychotic’on the role of thepared to one-half of the EDs and two-thirds ofderived distinguishingclinical features by plotting
the MEDs, and the PDs had a much longer
the probabilityof caseness against base rate foradmission.
While nearly all sample members revarious combinationsof the derived clinical feaceived antidepressant
medication,
the PDs weretures, akin to the ROC strategy. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
significantly
more likely to receive combination
antidepressant/antipsychotic
medication
and/or
ECT. We also reviewed the course of the PDs
Results
and MEDs for the 12 months after intake assessEach of the individual systems (DSM-III, RDC,
ment. The PDs had a distinctly
poorer clinicalcourse and a trend for a higher hospital readmisclinical) allocated quite different percentages(i.e.,
171 or 56%; 249 or 82%; and 145 or 47% respecsion rate.
tively) of subjects to the putative melancholic/
We now examine
differences
betweenthegroups on clinical features, first examining
signs
endogenous
category, with the RDC system being
the most, and the clinical system the least incluand then symptoms.
sive system. A total of 137 (45%) depressives met
Comparison of mental state signs
criteria for melancholia/
endogenous
depression
on zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
all three sy stems and form our sample, with 35
The total Core score, generated
by summingof them (the PDs) meeting the multiple criteriascores on the 15 mental
state signs, was 37.1
for putative psychotic depression
and the remain(median 38) for the PDs, 25.8 (median 24) for theEDs and 26.1 (median 24) for the MEDs. Table 1
ing 102 forming the ED subgroup.
The mean age of the 137 melancholic
subjectsshows that most of the signs were significantly
was 51.7 years, 88 (64%) were female, and themore likely to be present in the PDs compared to
137 had a mean duration of current illness of 46.6
both the EDs and MEDs, with a constructof(SD 62.0) weeks. We shall summarise
previously
greater psychomotor
retardation
subsuming
mostreportedsample characteristics(Parker
et al.,or all of those features. For all Core signs, the1991). The PDs and the EDs had similar marital
logit model fitted well and the odds of a more
rates and female preponderances,a similar likelisevere rating differed significantly
between PDs
hood of reportinga previous manic episode, andand EDs - except for an anxiety item. Table 1
similar rates of affective disorder, schizophrenia
shows that generally the PDs were at least three
and alcoholism in first-degree
relatives. The PDs
times more likely to be given a severer rating on
were 15 years older at initial assessment
and 12each item, and that the pattern
was similar
years older at onset of any affective disorder. At
whether the comparisongroup comprised EDs or
intake assessment,
the PDs and EDs did not
MEDs.
differ in depression
severity as self-judged on theZung scale, but the PDs did score significantly
Comparison of sy mptoms
more highly on the clinician-rated
Newcastle,
Table 2 compares
the two groups on a wide
Hamilton
and Core measures, suggesting greater
range of symptoms,
many being those held toutility of clinicianas against self-report-genercharacterise
the melancholicor endogenous
type
ated judgments.
Such differences
remained(onof depression.
While poor cognitive performance
all but matched variables such as age) when thewas also noted in the files of a number of subjects
PDs and MEDs were compared.
(almost entirely PDs), as testing was not obligaAs would be expected, historical data demontory or standardised,
we do not examinethatstrated that the PDs were much more likely thanvariablefurther.
As anticipatedfrom the rules

140
TABLE

1

PRESENCE

AND SEVERITY

Core sign

Sign categoricallyPDsn = 34

Non-responsive
tointerviewer
Dull and inattentive
Facial immobility
Self-preoccupied
Non-reactive
tointerviewer
Slumped posture
Limited mobility
Slowed movements
Slowed speech
Monosyllabic
speechPoverty of
associations
Impaired insight
Nihilism
Signs of anxiety
Endogenous
quality

OF COREEDs
n = 102SIGNS

SUBGROUPS zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPOIN THE THREE

present
MEDs
n = 34

Severity of sign (odds ratio, Y)
PDs vs. EDs

PDs vs. MEDs

PDs vs. EDs

testP
1v zyxwvutsrqponmlkjihgfedcbaZYXW
P
1v

x2

P

McNemartest

0.002
0.000 a0.180
0.000 “

5.57
8.34
4.83
7.28

Chi-square

0.000 a0.000 *
0.000 a0.000 ‘I.

PDs vs. MEDs

0.001
0.000 :’
0.005
0.000 d

79%
74%
94%
91%

44%
26%
76%
49%

44%
18%
80%
44%

12.8
25.1
5.6
18.8

0.000 ‘I
0.000 B
0.018
0.000 a

97%
77%
79%
74%
74%
74%

86%
41%
38%
38%
28%
34%

97%
44%
44%
41%
24%
47%

3.0
12.7
17.3
12.8
21.7
15.9

0.002 “
6.15
0.000 “
5.08
0.082
1.000
4.36
0.000 ‘I
3.00
0.016
0.000 I zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHG
0.019
5.37
0.000 a4.49
0.002
0.000 a0.004
5.21
0.000 ‘I
3.42
0.008
0.000 11 0.013
5.11
0.000 ‘%0.000 a6.41
0.000 i1
0.000 I
4.55
0.000 ‘I
3.64
0.005
0.000 a
0.064

85%
71%
68%
82%
94%

58%
22%
28%
77%
84%

74%
12%
24%
68%
85%

8.4
27.4
16.6
0.5
2.1

0.004
0.000 a0.000 a
0.474
0.144

0.424
0.000 a0.001*
0.267
0.453

4.05
10.32
6.30
2.32
4.53

0.000 d0.000 a0.000 *
0.022
0.000 ii

5.25
10.20
3.76
8.78

3.15
14.72
5.98
2.86
3.73

0.015
0.000 I
0.000 II
0.022
0.005

’ Test remains significant
after a Bonferroni
adjustmentof a/30.
This is based on one family for each type of analysis where,
within each type of analysis, the type 1 errors for EDs (15 tests) are expected to be correlatedwith those for MEDs (I5 tests) thus LYis divided by (15 + 151.

guiding allocation
to the PD group, delusions
and/orhallucinations
were the most specific features, with 34 of the 3.5 having a delusion(24
mood-congruent)and seven having hallucinations
during the episode. While most subjects had morethan one delusional
theme, we rated the predominant mood-congruent
themes as guilt (six patients), poverty (five), punishment(four), nihilism(four), worthlessness(three) and hypochondriasis(two). Ten subjects reported
mood-incongruent
delusions of persecution
or control as dominant.
The one patient without a delusion described an
auditory hallucinationof a single voice but was
unable to describe the content. Six other patients
admitted to hallucinations,
all auditory ones andmost usually (n = 5) of derogatory voices.
When comparison
was made of baseline symptom data, the PDs were significantly
more likely
than the MEDs to report delusions
and hallucinations (differences
determinedby definitionofthe groups), constipationand suicidal plans, wereless likely to report any early morning worsening

in mood, and showed contrasting
trends in being
less likely to report a non-variablemood but
more likely to report a sustainedmood disturbance on sub-analyses,
now detailed.
Diurnalvariation
was reassessedby reviewing case files
and progress notes. While any trend in baseline
self-reports
for the PDs to be less likely to reportan absenceof diurnal variation(Table 2) was
non-significant,episode data collected by clinicalstaff suggested that PDs were far less likely toreport any diurnal mood variation (Table 2). Secondly, in our coding of symptoms we allowed forseverity and persistenceof negative self-concepts
to be rated if affirmed. The PDs were more likely
to affirm the presence of a number of cognitions(e.g., sinfulness,
pessimism,
hopelessness,
helplessness, self-criticism
and lowered self-esteem),but even more likely than the EDs to rate atbaseline such cognitions
as being sustained
overthe defined rating period (i.e., the previous week).
This finding was in contrast with a trend for the
PDs to be less likely to report their mood as

141
TABLE

2

PRESENCE

OF SYMPTOMSACKNOWLEDGED

Symptom

BY DEPRESSIVES

PDS
n

EDs

%

n

IN THE THREE
MEDS

%

n

SUBGROUPS

PDs vs. EDs
76

Chi-squarePDs vs. MEDs
test

x2
Distinct mood
Persistent (i.e., non-variable)mood
No expectationof improvement
Sustained sense of sinfulness
Sustained pessimism
Sustained hopelessness
Sustained helplessness
Sustained self-criticism
Sustained worthlessness
Sustained fall in self-esteem
Appetite loss
Appetite gain
Weight loss ( > 3 kg)
Weight gain t > 3 kg)Complete loss of interest and pleasure
Anticipatory
anhedonia(complete)
Consummatory
anhedonia(complete)
CryingWould like to cry but unable
Totally non-reactive
if won lottery
Totally non-reactive
in social contact
Sustained sexual interest
Irritability
PallorConstipatedFeel retarded
Feel agitatedInitial insomnia
Middle insomnia
Terminal insomnia
Mood worst (patient report)
Early morning
Late morning
Afternoon/evening
No pattern
All the time
Absence of diurnal mood variation(as noted by staff)
Concentration
problems
Slowed thoughts
Preoccupied
with unpleasantthoughts
Preoccupied
with morbid thoughts
Suicidal thoughts ~ no plans
Suicidal plans
Thoughts of harming others
Hallucinations
Delusions

McNemar

test

P

35
34
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
35
34
35
34
32
28
35
35
35
35
35
35

94
21
43
71
91
80
86
86
71
91
89
6
57
0
66
60
3
43
34
59
49
15
56
50
66
86
49
51
43
60

99
102
100
94
101
101
101
100
100
99
102
102
102
102
102
102
102
102
102
102
102
100
86
79
102
98
99
102
102
102

91
38
14
36
55
55
54
71
59
77
73
15
42
15
43
44
2
67
19
33
32
20
73
29
35
71
52
44
52
65

34
34
34
31
34
34
34
33
33
33
35
35
35
35
35
35
35
35
35
34
35
33
24
19
35
33
34
35
35
35

88
35
21
26
44
50
50
52
48
48
68
20
40
14
46
46
0
57
23
35
31
33
58
21
34
76
53
37
57
63

0.39
0.531
0.687
3.20
0.074
0.267
0.000 ‘I
12.80
0.077
0.000 B
12.77
0.000 >’
15.42
0.000 il
0.000 a
0.007
7.13
0.035
11.45
0.000 B
0.004
0.084
2.98
0.007
0.192
1.70
0.057
0.059
3.55
0.004
0.053
3.74
0.099
0.164
1.94
0.179
0.124
2.36
0.210
0.016
0.062
5.78
5.31
0.021
0.189
2.63
0.104
0.332
0.98
0.754
1.000
0.013
6.19
0.383
3.65
0.454
0.056
6.92
0.134
0.008
2.96
0.085
0.263
0.47
0.494
0.179
3.13
0.077
1.000
3.99
0.045
0.344
0.001 il
0.027
9.83
2.82
0.093
0.388
0.09
0.765
1.000
0.56
0.454
0.359
0.86
0.481
0.353
0.618
0.25 zyxwvutsrqponmlkjihgfedcbaZYXW
1.000

35
35
35
35
35

29
0
11
37
23

102
102
102
102
102

58
3
12
16
12

35
35
35
35
35

63
6
6
14
11

8.93
1.05
0.00
7.19
2.57

35
35
35
33
35
35
35
35
35
35

51
100
89
85
69
37
26
11
20
97

100
102
102
91
102
102
102
102
102
102

17
96
85
73
63
32
13
3
0
0

34
35
35
27
35
35
35
35
35
35

3
97
89
59
54
31
3
0
0
0

16.0
1.41
0.23
2.00
0.39
0.27
3.25
3.87
21.50
131.79

0.003
0.304
0.957
0.007
0.109

0.012
0.500
0.687
0.096
0.344

0.000 ‘I
0.234
0.628
0.157
0.535
0.605
0.071
0.049
0.000 110.000 ‘I

0.001 a
1.ooo
1.ooo
0.092
0.359
0.774
0.021
0.125
0.015
0.000 ila Test remains significant after a Bonferroni
adjustmentof (Y/90. This is based on one family where the type I errors
tests) are expected to be correlatedwith those for MEDs (45 tests) - thus (Y is divided by (45 + 45).

for EDs (45142

non-variable
when asked a single-item
questionas to whether their mood was ‘persistentno matter what is done’. We interpreted
the dissonanceas reflecting
inappropriate
wording of our ‘persistence’ item, with it actually assessing ‘reactivity’. We therefore elected to focus on the several‘sustained’ cognitive ratings (much more likely tobe affirmed by PDs) and we used LCA to reduce
the number of those cognitive items to four (viz.
pessimism
about the future, hopelessness,
helplessness and worthlessness).
Comparisonof diagnosis with class membershipdefined by the four
items showed that, while nearly all PDs reported
a sustainedmood disturbance,a significant
percentage of EDs did so too. Put another way, thissuggested that a diagnosis of PD was unlikely ifsustainedmood disturbance
was not reported,
but acknowledging
a sustained mood disturbance
did not carry much diagnostic weight as a majority of both the PDs and the EDs affirmed such acharacteristic.
Importantly,
the PDs were no more likely toreport appetite loss, weight loss, insomnia (of any
phase), to judge their mood as less reactive, or toreport subjective psychomotorchange (either agitation and/or
retardation).
The last finding is ofinterest, as retardation
sharply distinguishedthegroups when it was assessed as an observed sign.
We considered
whether
several of the signs(i.e., of psychomotorchange) and symptoms (i.e.,
constipation)
might be effects of medication,
andtherefore
examined
drug treatment
current
atintake assessment.
Specific details are given in
our earlier report (Parker et al., 1991) of theprevalenceand dosage of differing psychotropic
drugs across groups. As the PDs were less likely
to be receiving antidepressant
medication
and assimilar numbers of PDs and MEDs were receiving antipsychotic
medication,
we judged
thatover-representationof the features of interest in
the PDs was likely to reflect the disorder and noteffects of medication.
Do psychoticof delusions
tinct clinicaldepressives (defined by the presence
and /or hallucinations)have disfeatures?

In addressing
this first objective, we elected
not to include all items (or all items significantly

distinguishing
PDs from EDs in Tables 1 and 2)
in a procedure such as a stepwise multiple regression as we would have (1) paid a price in degrees
of freedom,and (2) expected less reliable estimated coefficients,
requiring
more cross-validation. We favoured assessmentof a small numberof ‘global’ variables, if possible, as predictor variables. Thus, insteadof entering
a numberofindividual
signs (demonstrated
as significant
inthe univariate
analyses reported
in Table 1) weentered the total Core score categorisation
and,as the sustained
depressive
content
items appeared to reflect a homogeneous
construct,
theywere reduced to one item reflecting
latent classmembership.
The remaining
items (constipation
and absence of diurnal mood change) were theonly significant items (after Bonferroni
correction
and apart from delusions and hallucinations)distinguishing
the PDs and EDs in the univariate
analyses.
Each was also examined
as a dichotomised variable (i.e., 1 versus 0) in the subsequent analyses, as now explained,
together withsome theoreticalrationale.
(i> A total zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQ
Core score of 29 or more: in thecourse of previous work (Parker et al., 1990) we
identified(through mixture analysis in two samples with a broad compositionof all depressive
types - one which included most of the patients
reported
here and the other a quite separate
sample) populationsof high scorers on the Core
which proved to comprise mainly clinically diagnosed psychotic depressives.
A score of 29 was
the lower of the two cut-offs in the two samples
and was selected as the cut-off in this analysis.
The Core variable was so selected as a measureof psychomotorchange, being the most consistentfeature (other than delusions and hallucinations)described
in association
with psychotic depression.
(ii) Allocation
to the sustained depressiae content class on the basis of the LCA noted earlier.
(iii> The absence of any diurnal variationinmood, as assessed by staff observationnodiurnal uariation: while our univariate
analyses
identified
this item, there is also some clinicalevidence to support its inclusion, with Healy andWilliams (1988) noting a German observationthat‘in the severest cases, as patients
become progressively
more psychomotor
retarded,
diurnal143

variation of mood is often lost’. Additionally,weEDs but only 62% (21/34) of the PDs (K = 0.49).
have noted (in the Introduction)that this feature
For a patient to be assigned as psychotic, he oris includedin the ICD-9 definitionof ‘reactive
she needed to be positive on core and at leastdepressive psychosis’.
one of the two other variables. In essence, while(iv) Constipation:
the previous univariate
analthe model was an appropriate
one for the data, it
yses identified
this item, but it has also been
indicated only a moderatecapacity for our ‘nonnoted in a number of reports. For example, Kraepsychotic’
predictor
variables(i.e., albeit withpelin (1907) described
physical symptoms in thedelusionsand hallucinations
excluded)
to cor‘delusional
form’: ‘The appetite
is poor, therectly classify the two clinically diagnosed groups.
tongue coated, and the bowels constipated’
(p.
402).
Is a diagnosis of psychotic depression dependent
As the presence of delusions
and/orhallucion establishing the presence of delusions and /ornations was correlated perfectly with our diagnoshallucinations?
tic allocation (by definition),
it was not appropriHere we examine the utility of the four variate to include it in the analyses, which will now
ables listed earlier, but now with delusions and/or
be described.
Clinical assignmentof subjects as PD or ED
hallucinations
added (variable termed hafdel) in
defining
a separate
class (be it categoricallyor
was the outcome variable in a logistic regression
analysis, with the four variables listed in the predimensionallydetermined),allowing us to assess
the extent to which each of the five refined cliniceding paragraphs
and their interactions
as thepredictor
variables(with full data sets for 125
cal features meet necessary and/or
sufficient crisubjects: 34 PDs and 91 EDs). As the interaction
teria. We first fitted a one-class model to the 125
terms made little difference
to the fit of theavailable subjects which showed a poor fit to themodel, and as it appeared
unlikelythat theirdata (x2 = 95.64, zyxwvutsrqponmlkjihgfedcbaZYXWVUT
df 26, P < O.OOOl>, arguing
against there merely being one ‘type’. We thenestimates were not finite (Aitken et al., 19891, theinteraction
terms were dropped.
By the first asfitted a two-class model (see Table 3) which gave
sessment strategy, the model fitted the data wella good fit to the data (x2 = 11.17, df 20, P =(Pearson x2 = 109, df = 120, zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
P = 0.75) with only
0.94), though the effect of the low numberof
5/12.5 patients(all PDs) being particularly
dissubjects can be seen in the high standard errors.
crepant.
Additionally,
it provided
a significant
In the latter analysis, one class, with an estimatedimprovement
over the null model (decreaseinprevalenceof 36%, was defined in one of two
deviance = 47.57, df = 0.4, P < 0.0001) with three
ways: either by the presence of haldel or by anitems significant
by the approximate
t values.
appropriate
pattern of positive responses
to theRe-fitting
the model with sustained depress&eother four items, but requiring the definite inclucontent deleted
resulted in a non-significant
insion of core. Thus the presenceof delusions
crease in the deviance(x2 = 1.71, df = 1, P=
and/orhallucinations
was a sufficient,but not
0.19)‘withall three items significant
by the apnecessary,condition
for assignment
to this firstproximate t values: core (t = 4.43, P < O.OOl), noclass. The other class, with an estimatedprevadiurnal uariation (t = 3.34, P < 0.001) and constilence of 64%, was definedby the absence of
pation (t = 2.46, P < 0.01). Expressing
the coeffihaldef and a low rate of affirmationof the othercients as odds ratios, we establishedthat patientsfour features. When compared against diagnosis,
positive on core (effectively showing pronounced
the solution
shows high sensitivity,with 34/34
psychomotorchange) were 10.8 times more likely(100%) of the PDs being assigned to the firstto be clinically diagnosed PD; those affirming noclass, but weaker specificity, with 80/91 (88%) ofdiurnal uariation were 6.2 times more likely, andthe EDs being assigned to the second class (K =those positive on constipation were 3.5 times more0.80). We then had an independent
re-examinalikely.
tion of the case files of those 11 patients clinically
By the second assessment
strategy, the logistic
diagnosed
as non-psychotic
but allocated to theregression
correctly
assigned
78% (79/101)
of‘psychotic’
latent class. Such subjects included

144
TABLE

3

LATENT CLASS ANALYSIS
OF FIVE
TION AND CLINICALDIAGNOSIS
SampleVariable

BINARYITEMS,AND CORRESPONDENCE

BETWEENLATENT

CLASS

SOLU-

comparison
PDs vs. MEDs

PDs vs. EDs
Probability of positive
for member of class(standard error)
Class I

Probability of positive
for member of class(standard error)

response

Class II

response

Class IClass II

Hallucination
or delusion
High Core score
Constipation
No diurnal mood variation
Sustained depressive content
Estimated prevalence

0.76
0.80
0.57
0.45
0.90
0.36

(0.09)(0.07)(0.08)(0.08)(0.05)(0.06)

0.00
0.20
0.29
0.15
0.52
0.64

(0.12)(0.05)(0.06)(0.04)(0.06)(0.07)

1.oo
0.81
0.59
0.53
0.91
0.50

(“1
(0.07)(0.09)(0.10)(0.07)(0.09)

0.05
0.37
0.28
0.00
0.53
0.50

(“1
(0.09)(0.08)(0.13)(0.06)(0.09)

Clinical diagnosis
Psychotic melancholia
Non-psychotic
melancholia
Total

34
11
45

(100%)
(12%)
(36%)

(0%)
(88%)
(64%)

34

8::
80

(lOO%“o)
(0%)
(53%)

3::
30

(0%)
(100%/o)(47%)

Goodness of fit:
Test for two classes vs. onex2 = 11.17, df 20, P = 0.94.
x2 = 10.09, df 20, P = 0.97.
x2 = 84.47, zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
df 6, P < 0.001.
x2 = 62.24, df 6, P < 0.001” Numericaldifficultyin calculating

this standard

3:

error.

patients
with ‘pathologicalconcerns
about impending
disaster’,‘hypochondriacal
concerns
about cancer’ and a ‘strange concern about notwashing hair’, and chart review establishedthat
three were definitely delusional
in a previous orsubsequentepisode. In retrospect, we judged thatnine of these 11 patients
may well have haddelusionalfeatures but failed to express or acknowledge
them with sufficient
clarity to meetstrict entry criteria.
In Fig. 1 we have plotted the probabilityof aperson being in the psychotic class (given thatthey have affirmed the indicated items) as a function of base rate. Because haldel is a sufficientcondition(i.e., the probability
is always close tol.O>, the figure assumes
haldelis absent. The
figure shows how the items relate to each otherand how their relative utility changes according to
the base rate. The probabilities
for the varying
combinationof variables suggest that a high corescore and sustained depressive content provide astrong predictive set.
The latent class analysis was repeatedon thesubset of PDs and MEDs, with full data sets

being available for 64 subjects. The results werevery similar to the first analysis, and the fit wasgood (x2 = 10.09, df= 20, P = 0.97). In this sample all the clinically diagnosed
PDs were allocated to the first class, and all the MEDs to the

2
5
0

1

12 0.9zzyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCB
.c
0.6
:

t
.
B

0.7

:,
._
5
0
f

0.5

0.6

0.4
0.3

6
w.
C
.z

0.2

2e
a

0

0.1
0

0.1

0.2

Prevalence

0.3

0.4

0.5

of ‘Psychotic’

0.6

0.7

Latent

Class

0.6

0.9

1

in Sample

Fig. I. Positive responses
to items and probabilityof being
psychotic as judged by presence of four clinical features (butnot including delusions or hallucinations).

145

second class (K = l.O>, thus demonstratingcomplete agreement
between clinician diagnosis andthe LCA.
Discussion
The significanceof seeking to define psychotic
depression
clinically and distinguishit from nonpsychotic melancholia
emerges from the specificfinding noted in the Introductionthat thepsychotic
condition
responds
poorly to antidepressant
medication
alone, and that there is adistinctly
improved
outcomewith combination
antidepressant/antipsychotic
medication
and/or
ECT. In this report we pursue a phenomenological definitionof psychotic depression,
examining,in essence, whether delusions
and/orhallucinations are necessary
and sufficientfeatures.
Our
comparisongroup reflected what we judged to bea nosologicaland clinical priority to distinguish psychotic from non-psychotic
melancholia
and not from all residual depressive conditions.
Several possible study biases will first be considered. It is unlikely that our PDs included subjects with schizophrenia
as all subjects were assessed by one or more psychiatrists
to exclude
alternative
diagnoses,
clinical and historicaldetails were reviewed by an independent
psychiatrist, we used both operational(DSM-III
andRDC) and commonlyused clinical criteria fordiagnosing
the depressive
disorder,and we reviewed (and changed
if necessary)all episodediagnoses at a 12-month follow-up.
As allowed by the DSM-IIIR
system, the presence of ‘mood-incongruent’delusionsand hallucinations
does not alone reject a diagnosis
ofdepression.
In fact, as we have noted elsewhere(Parker
et al., 19911, the rate of mood-incongruent delusions in our sample (10/34, 29%) was
lower than rates reported in four other studies ofpsychotic depression(Nelson and Charney, 1981;
Frangos et al., 1983; Coryell et al., 1984; Lykouras et al., 1985).
Any bias emerging from our sample being derived from a specialised
centre, which has a significant
numberof referralswith chronicand‘treatment-resistant’disorders,is more likely toaffect some of our descriptive data (e.g., ratios ofpsychotic/non-psychotic
melancholies)
but should

not have distorted our quantitative
comparisonofpsychotic and non-psychotic
melancholies.
In contrast
to most studies, our PDs weremore than a decade older than the EDs at bothintake and initial onset, and only 14% (5/35) of
the PDs as against 40% (40/101) of the EDs had
their first episode of depressioncommence
before the age of 30 years. But, as our focus was onclinical rather than ‘risk’ or backgroundvariablesin defining psychotic depression,and as an older
age is not generally described, we did not include
it in our multivariate
analyses. Additionally,
weincludedan age-matchedcomparisongroup toexamine for age effects.
We examineda more comprehensive
list ofclinical features than previous studies and confirmed the three most clearly suggested previous
findings
that PDs were no more likely toreport a number of vegetative features (e.g., appetite or weight change, insomnia),that they evidenced greater psychomotorchange (quantified
in this study by a sign-based
system), and that,while they reported
a more severe mood disturbance, it was distinguishedmore by being sustained than by severity. Additionally,
we noted
both constipation
and an absence of diurnal variation in mood to be more likely and have earlier
noted historical support for these findings. It is
important
to note that two of the differencesdid
not emerge when we relied on self-reportdata,
an issue we will return to shortly. If the suggested
distinguishingfeaturesare replicated(and wewould encouragesuch studies to examine bothself-reportand observationaldata), such studies
should assess whether
any absenceof diurnal
variationis intrinsic
to PD, or a phenomenon
related more to psychomotorchange. The phenomenon
is clearly consistent
with the tendencyof the PDs to report a sustainedmood disturbance (as defined).
Importantly,
we found nosupport for the possibility that these and related
features might be a reflectionof the PDs being
more likely to be receiving antipsychotic/antidepressant
medicationor higher doses of thosedrugs, and interpretthe disturbanceas fundamental to the depressive disorder itself. It couldbe, however, that the observed differenceswere
the result of inadequate
treatmentof the PDs.
Our mental state system demonstrated
a large146

number of significant
differences,with that sysestablisheda moderate predictive potential.
This
tem largely underpinnedby psychomotorchange,was, in effect, a test of the superfluousnessof theand with the differencessuggesting retardationto‘psychotic’ item. The assumption
underlying
thebe the most distinct construct. Our initial version‘top-down’ strategy - that the existing diagnosticof the zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
core system favoured
retardation
at thesystems provide a ‘gold standard’ classification
expense of agitation
items (an issue being reof course remained
to be establishedrather thanvised), so that the relevanceof agitation
will
merely supported by a set of best predictors.
require reassessment.
Nevertheless,we find that
The second, or ‘bottom-up’
strategy, used lamost clinically agitated patients rate as ‘high core’
tent class analysis to isolate allied characteristics
subjects, perhaps
becauseas Widlocher(1983),
best defining the two groups or, at least, distinamong others, has observed,‘even grossly agiguishing one group from the other. Thus, in comtated patients have been shown to have retardaparison to the earlier logistic regression,
we didtion’. The most distinct mental state sign differnot use the initial criterion
diagnostic
allocation
ences between the PDs and EDs were that theto shape how the associations
among the variPDs were more likely to be dull and inattentive,
ables in the set were used. While total agreement
self-preoccupied
and non-responsive
to the interbetween the latent class analysis solution and theviewer. As expected, they showed more impairclinical diagnosis of PD or MED was established,ment of insight. Regrettably,
we failed to include
agreement
was somewhat
lower for the PD vs.
a test of cognitive function in our initial clinical
ED comparison.
As noted, the latent class analyassessment, with our observationof a much higher
sis effectively reallocated
11 clinically diagnosed
rate of cognitive
disturbancein the PDs being
EDs to class I, the putative psychotic depression
based on an incomplete
review of case notes. As
class. Here we face a key issue. Did the dissonant
a consequence,
we did not include this variable inallocationof 8% of the total sample in that
our multivariate
analyses, although
it may wellanalysisreflect limitationsof the multivariate
have been subsumed there by a higher-orderconanalysis, or could we have mistakenly
diagnosed
struct of psychomotorchange. In any replicationsome depressives clinically due to stringent entry
study, we would favour the addition of a simple,
criteria - because they failed to disclose delustandardised
test of cognitive function, as a clinisions or hallucinations,or because significant psycal diagnosis or observationof ‘pseudodementia’chomotorchange prevented
their acknowledg(see review by Mahendra,
1985) is frequently
ment - or because we erroneously
rated sometrue delusions as being non-psychotic
over-valued
associated with intensity of depression.
We now consider
our central
objectives
ideas? Chart review supported both views and we
which examined,
in essence, the necessary
andtherefore
have some confidence
in the allocation
sufficient
status of delusions
and/orhallucinaof cases by the latent class strategy.
As noted earlier, the finding that delusions
tions, with that objective addressedin two ways.
The first, or the ‘top-down’strategy,
assumedand hallucinations
were sufficient but not necessary to allow a diagnosis of ‘psychotic depression’that our diagnostic
subclassification(dependent
on delusions/hallucinations)
was valid, and weis of key clinical importance,
for it suggests that
restricting a diagnosis of ‘psychotic depression’ totherefore compared the clinical features of those
assigned to PD, ED and MED classes on such a
depressive disorders only when delusions and/or
hallucinations
have been elicited, as favoured inbasis. In the logistic regression
analysis, as the
DSM-IIIR,
may be in error - and leads to thepresence or absence of delusions and/or
hallucinations
dictated
initial assignment
to the tworisk of inappropriate
treatment.
In conjunction
with findings for retardationand diurnal variacomparisongroups, and therefore correlated pertion, suggesting dissonance between self-reported
fectly with the criterion
diagnostic
group, thatand observed depressive manifestations,
we would
item could not be included in the analysis - as it
argue that psychotic
depression
may often bealone would have been a ‘total’ predictor.
We‘masked’, and the diagnosis missed if reliance istherefore
limited consideration
to the four remade on self-reportsof the subject. We would
mainingvariablesin a logistic regression,
and

147

argue for a high index of suspicion,in the absence of formally eliciting
delusions/hallucinations, when there is severe psychomotorchange- as suggested in some diagnostic systems (e.g.,
DSM-III which includes a ‘depressive stupor’ criterion).
Clearly, the features we have isolated require
replication
in independent
study groups before
acceptance,
but are compatible
with historicaland clinical observations
about psychotic depression over the centuries(Jackson, 1986) and with
one of the few cluster-analytic
studies with alabelled ‘psychotic’ group (Paykel, 1971). In thatstudy, nine of the 24 (37%) cluster-partitioned‘psychotic’ group had delusions,they returnedahigher global rating of severity of illness score,
were older, were rated as more retarded,agitated, paranoidand hypochondriacal,
had less
insight, were more likely to be constipatedandmore likely to have a ‘distinct quality’ to theirdepression.
We suggest that the present study hassuggested a set of clinical criteria that may wellassist clinical assignment,
as well as allow greater
precisionin risk factor and treatment
outcomestudies, and are worthy of closer operational
definition and replication
studies, perhaps also examining their utility against current nosologicalcriteria.
Acknowledgements
This study was supportedby the NH&MRC(Australia)
and a Prince Henry Hospital
Coast
Centenary
grant. Research
assistance
was provided by Kerrie Eyers, Margaret
Cooney, Christine Taylor,
Fadil
Pedic,
Kay Roy, Janelle
Buchanan, Janjana Arasaratnam
and Simon Abel.
Professor John Snowdon provided helpful advice.
Sandra Evans, Yvonne Foy, Lindy Wright, Mark
Pearson and Noel Uhe assisted with manuscript
preparation.
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