14,

15.

16.

17.

18.

McFarland RA, Barach AL. The relationship between alcoho! Intoxication
and anoxemla. American J. Med. Sclence 1936;192(2):186-98.

McFarland RA, Forbes WH. The metabolism of alcoho! in man at high
altitudes. Human Blology 1936;8(3) :387-98.

Mertens, HW, Collins, WE. The effects of age, steep deprivation, and
altitude on complex performance. Hum. Factors 1986;28:541-51.

Newman HW. The effects of altitude on alcohol tolerance. Quarterly J.
of Studles on Alcoho! 1949;10:398-403.

Thackray, Ri, Balley, JP, Touchstone, RM. Physiological, subjective,
and performance correlates of reported boredom and monotony while
performing a simulated radar control task. In: R. R. Mackie (Ed.),
Vigilance: Theory, operational performance and physiological
correlates, London, Plenum Press, 1977;203-15.

we:

18

U.S. Government Printing Office : 1988 - 516-018/80261


Individual tasks except pattern Identification. The older subjects also
showed more performance Impairment at the higher levels of workload than did
the younger group. Alcoho! ingestion resulted [In significant performance
Impairment for both age groups, but the 60-69 year age group was more
negatively affected; performance for both groups appeared to show full

\ »,,recovery by the sixth postingestion hour. Altitude had no deleterious effect
‘ “on performance elther as a separate main effect or as an interaction with

aicohol. Mood scores differed between the age groups only for "tiredness" and
"boredom"; In both cases the scores favored the older subjects (l.e., they
reported being tess tired and less bored).

Alcohol. The Ingestion of alcohol resulted In significant Impairment for
scores on all individual tasks and MTPB composites. That impairment persisted
for several hours with all group scores appearing to show full recovery by the
6th postingestion hour. Significant Impairment due to alcohol has been
demonstrated for other filght-related tasks at blood alcohol levels (BAL's) as
low as 30-50 mg % In-ftight simulator studies (1,7,8) and at 40 mg % during
Inflight studies (2). A laboratory study of tracking performance showed
performance decrements during angular acceleration, but not when subjects were
statlonary, at a peak BAL of 27 mg % (6).

Workload. Although significant workload effects were observed In performance
In all tasks, the only substantial Interaction of workload with other factors
was the Interaction of age group with workload in monitoring performance.
Monitoring performance scores tended to decrease silghtiy with workload In
younger subjects, but large decrements in monitoring scores were observed In
the older subjects. The greater sensitivity of older subjects to variations
In workload Is a common finding In MTPB research.

Effects. The results from this study share some features in
common with five previous experiments from this laboratory, none of which
reported any effect of 12,000-12,500 ft (3658-3810 m) altitudes on breath or
blood alcoho! leveis, and none of which found any synergistic Interaction of
those altitudes and alcohol on performance scores. The findings of those five
studies, however, are at some variance with a commonly held view rooted in an
authoritative textbook by McFarland (12), wherein he concluded that “...the
alcoho! in two or three cocktalts would have the physiological action of four
or five drinks at altitudes of approximately 10,000 to 12,000 ft." Also,
“Airmen should be informed that the effects of alcohol are similar to those of
oxygen want and that the combined effects on the brain and nervous system are
significant at altitudes even as iow as 8,000 to 10,000 ft." (And, ina
subsequent paper (13), "...the alcohol In two or three cocktails taken at
6-8,000 feet cabin altitude would tend to have the effects of four or five
cocktalls at sea tevel.") Those conclusions, based primarily on the results of
McFarland's own ploneering studies (14,15) and one by Newman (17), have a
physlotogical basis. Because the oxygen uptake of tissue cells Is reduced
both by alcohol (histotoxic hypoxia) and In a different way by altitude
(hypoxic hypoxia), an Interaction, at least additive (13) and perhaps
synergistic, of the effects of alcohol and of altitude on performance might be
expected.

The major research leading to these conclusions was reported In 1936 by
McFarland and Forbes (15), who served as the subjects In unique exper iments

H conducted In the Andes Mountains. Blood alcohol values at two altitudes
t (12,200 ft and 17,500 ft) rose more rapidly and reached higher levels than did

12


Procedure. Following 21 h of training on the MTPB, subjects participated In
four experimental! test sessions spread over a two-wk period with at least two
days between sessions. Subjects were tested in groups of 3-5, with members of
each age category In each group tested. The four test conditions included the
four possible combinations of the two altitude and two drug conditions. The
altitude conditlons were 12,500 ft (3,810 m) or ground level (approximately
396 m). Altitude simulation was accomplished by gas mixtures (13.5% oxygen
and 86.5% nitrogen) administered through face masks worn by subjects. These
mixtures were verified by analyses with a model MGA-1100, Perken-Elmer Medical
Gas Analyzer. Compressed air was used for the ground level condition.

Subjects drank equal volumes of elther a placebo or an alcoholic drink at the
start of each session. Alcohol doses were 2.2 mL of 100-proof vodka per kg of
body welght mixed with three parts of either tomato or orange Juice, as
selected by the subjects. The placebo drink contained a few drops of rum
extract floated on top of !ce cubes primarily to produce the odor of an
alcoholic beverage. Subjects consumed each drink In a 20-min period; testing
began 30 min after drinking was completed.

In alt four experimental conditions, the morning MTPS performance session
began at 0900 and Involved three repetitions of the basic 1-h work schedule,
ending at 1200. After a jiunch break, the afternoon session began at 1300 and
Involved a similar schedule. During every morning and afternoon session,
subjects breathed the appropriate gas mixture for the entire 3-h duration.
Mood rating scales were administered before the morning performance session
and after both morning and afternoon’ sessions. Subjects rated mood, on
nine-polnt scales, regarding levels of attentiveness, tiredness, boredom,
tenseness, and Irritation (18).

RESULTS

Mean breathalyzer readings peaked around 8&8 mg X% and did not
differ between age groups or altitude conditions (see Fig. 1).

MIPB Performance. Mean performance scores for each of the seven Individual
tasks of the MTPB and for the three types of composite scores (l.e., overall,
monitoring, and active tasks) are presented in Table 1 for the four conditions
and the two age groups. Overali composite score means (all seven tasks
combined) were also calculated separately for the two age groups by successive
work hours for each of the four drug/placebo conditions (see Fig. 2). The
best performance for both age groups occurred under the placebo conditions;
there were no differences in placebo scores for ground levei vs. altitude.
Alcohol depressed scores for both age groups, but more so for the older group;
again, there were no differences In scores between ground level! and altitude
(see Fig. 2).

Analyses of variance (see Table 2) of the Overall Composite Scores (all tasks)
Indicated significant (p < .001) differences’ in performance favoring the
younger age group, and favoring placebo over alcohol conditions; performance
during later time periods was significantly (p < .05) better than early work
hours (due to alcohol effects). Only three interactions were significant:
age group x time (p < .05), drug x time (p < .001), and age group x drug x
time (p < .05). These interaction effects are apparent in analysis of Fig. 2
and are related to the fact tbadeesFeshet more strongly. depressed older


|

With respect to the age groups studied, results from this research suggest
that:

1) BAL curves do not vary as a function of age group at ground level or at
altitude. :
The detrimental effects of alcohol on performance are greater In the
older subjects, especially during the first few hours following
drinking.

3) The detrimental effects on performance of the alcohol dosage used
disappears within eight hours for both age groups.

& the age group-alcohol Interaction ts not affected by altitude.

16


Table 3.-Results of Analyses of Variance Conducted Separately for the Seven
Individual Tasks of the Multiple Task Performance Battery.
statistical significance for all main effects are presented along with
interactions that proved significant.
terms yielded no significant effect for any of the comparisons.

Individual Tasks

Levels of

All other (unlisted) interaction

]
‘ALL MAIN LIGHTS ARITH- PATTERN PROB TRACK- ‘
EFFECTS GREEN RED METERS METIC IDENT SOLV ING
Age Group (Ag) -001 .05 =. 01 OL +001 05
Drug (D) 2001 201 001 001 2001 +001 2001
Altitude (Al)
Time (T) -001 -001 05 201
Workload (W) 2001 001 001 001 001 001
Only Significant
Interactions
Ag xT -001
Ag xW -0l 601 «001
DxT 001 05 2001 -001 01 201
DxwW 01 205
TxW 01 205 001
AgxDxT 05 -001 205
Ag x Al x W 205
AgxTxW 05 !
ALxTx -05 I
Agx Dx AlxW 205
AgxDxTxW 205


Table 1.-Standard MIPB Scores (Means and Standard Deviations) for
Composite and Individual Task Measures as a Function of Age Groups,
Drug (alcohol vs. placebo), and Altitude (ground vs. 12,500 ft).

Measures 30-39 yr group 60-69 yr group
Placebo Alcohol Placebo Alcohol
Composite Gad Alt Gnd Alt Gnd Alt Gnd Alt
Overall Mean 534 537 518 516 487 490 465 461
Composite S.D. 30 26 «638 «46 33. 30 43) 45
Monitoring Mean 533 540 523 523 486 485 466 454
Composite S.D. 30 28 #41 46 44 43 46 55
Active Tasks Mean 534 536 514 510 488 494 465 466
Composite S.D. 33° 30 «4552 36 32 «52049

Individual
Task

Green Lights Mean 556 551 540 534 474 475 442 441
S.D. 35° 39 «43 SL 74 65 69 65
Red Lights Mean 513 530 502 523 489 497 479 472
S.D. 75 52 79 55 48 S51 48 61
Meters Mean 530 538 526 512 493 482 477 450
S.D. 35° 17) 360 74 56 62 «468 107
Tracking Mean 539 533 523 507 480 486 470 469
S.D. 59 67) «7551 43 53 47) 48
Arithmetic Mean 532 537 523 517 488 491 456 464
S.D. 33° 410 43 43 47 44 81 72
Pattern Mean 525 533 483 488 510 517 480 467
Ident. S.D. 47° 42 «102 120 62 43 85 92
Problem Mean 541 540 527 528 476 484 453 461
Solving S.D. 46 46 60 57 46 34 78 56


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REFERENCES

Aksnes EG. Effect of small dosages of alcohol upon performance in a
Link trainer. J. Aviation Med. 1954;25:680-88 and 693.

Billings CE, Wick RL, Gerke RJ, Chase RC. Effects of ethyl alcoho! on
Pllot performance. Aerospace Med. 1973;44(4):379-82.

Coltins WE. Performance effects of alcohol Intoxication and hangover at
ground level and at simulated altitude. Aviat. Space Environ. Med.
1980 ;51(4) :327-51.

Collins WE, Mertens HW, Higgins EA. Some effects of alcohol and
simulated altitude on complex performance scores and breathalyzer
readings. Aviat. Space Environ. Med. 1987;58(4):328-332.

Fowler B, Elcombe DD, Kelso B, Porller G. The threshotd for hypoxia
effects on perceptual-motor per formance. Hum. Factors
1987 ;29(1) ;61-66.

Gilson, RD, Schroeder, DJ, Collins, WE, Guedry, FE. Effects of
different alcohot dosages and display Itlumination on tracking
performance during vestibular stimulation. Areospace Med.
1972; 43:656-60.

Henry PH, Flueck JA, Sanford JF, Keiser HN, McNee RC, Walter WH Wi,
Webster KH, Hartman 80, Lancaster MC. Assessment of performance In a
Link GAT-1 filght simulator at three alcoho! dose levels. Aerospace
Med. 1974;45(1):33-44,

Henry PH, Davis TQ, Engelken EJ, Triebwasser JH, Lancaster MC. Alcohol-
Induced performance decrements assessed by two Link trainer tasks using
experienced pilots. Aerospace Med. 1974; 45(10):1180-89.

Higgins EA, Davis AW, Vaughn JA, Funkhouser GE, Galerston EM. The
effects of alcoho! at three simulated aircraft cabin conditions.
Washington, OC, 1968; FAA Office of Aviation Medicine Report,
FAA-AM-68~18.

Higgins EA, Vaughan JA, Funkhouser GE. Blood alcohol concentrations as
affected by combinations of alcoholic beverage dosages and altitude.
Washington, DC, 1970; FAA Office of Aviation Medicine Report,
FAA-AM-70-5.

Lategola MT, Lyne PJ, Burr MJ. Alcohol-Induced physlological dis-
Placements and their effects on flight-related functions. Washington,
DC, 1982; FAA Office of Aviation Medicine Report, FAA-AM-82-3.

McFartand RA. Human Factors In Air Transportation. 1953. New York:
McGraw-Hill.

McFarland, RA. Man In rarifled atmospheres. Technology Rev. (Alum.
Assoc. MIT) 1973;75 (6):1-10.

7


subjects’ scores, particularly during the three time periods that comprised
the morning session. There was no interactive effect of alcoho! and altitude.

TABLE 2.-Results of analyses of variance conducted separately for the
overall composite scores and the composite scores for the four active
tasks (mental arithmetic, pattern identification, tracking, problem
solving) and for the three monitoring tasks (meters, red and green
lights). Levets of statistical significance for all main effects are
presented along with interactions that proved significant. All other
(unlisted) Interaction terms ylelded no significant effect for any of the
compar I sons.

COMPOSITE SCORES

Actlve Monitoring

ALl Main Effects Overall Tasks Tasks
Age Group (Ag) -001 -001 001
Drug (D) -001 -001 001
Altitude (Al)

Time (T) +05 -05
Workload (W) N/A N/A 001

Only Significant
Interactions

Ag x T .05 -01

OxT -001 +001 01
Ag x W N/A N/A -001
Ag x OxT -05 -01

Separate analyses were conducted to assess the effects of the experimental
conditions on (1) composite scores for monitoring performance (red Iights,
green tights, and meters; the three tasks common to all workload conditions)
and (11) composite scores for the four active tasks (mental arithmetic,
pattern Identification, tracking, problem solving). The latter yielded
results almost Identical to that obtained for the overall composite scores
with the exception that the 3-way Interaction (age group x drug x time) was
not significant (see Table 2). The monitoring tasks analysis, the only type
of composite score analysis to Include the variable of "workload", showed the
familiar significant (p < .001) main effects of age (favoring the younger
group) and drug (favoring the placebo) as wel! as that of workload (favoring





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dimension to a green dot target; the subject counteracted the disturbance
to keep the dot at screen's center by moving a control stick. Performance
was measured In mean vector absolute error and mean vector root mean square
error.

Problem salying. Subjects had to discover the correct sequence In which to
press five response buttons, using a trial-and-error process with a
left-to-right search procedure. Pressing a button In incorrect order
caused a red light to turn on and stay on untlt the next correct response
was made. Pushing all five buttons In correct order caused a blue IIght to
turn on. After a problem was solved, the same prob!em was re-presented
after a lapse of 15 s; the subject had to reenter the previous solution
from memory on this confirmation presentation. Performance measures were:
(i) mean response latencies for the first solution and confirmation stage
and (li) the mean number of errors per problem made during the confirmation
stage.

MIPB Worktoads. MTPB tasks were aiways administered in a basic 1-h schedule
that involved five 10-min Intervals of work under various combinations of MTPB
tasks followed by a 10-min rest period. All five workload intervals Involved
monitoring of red and green warning lights and meters. The first 10-min MTPB
Interval Clow workload) included tracking in addition to monitoring. The
second interval (moderate workload) Involved mental arithmetic, problem
solving, and monitoring. The third interval (moderate workload) Involved
problem solving, tracking, and monitoring. The fourth Interval (high
workload) Involved problem solving, target Identification, and monitoring.
The fifth 10-min Interval (high workload) Included mental arithmetic, pattern
Identification, and tracking, In addition to monitor ing.

Performance was assessed In terms of composite scores for each task.
Composite scores summarized all measures of performance for the particular
task. An overall composite score (all tasks) was also obtained, as well as a
composite score for the three monitoring tasks (red lights, green lights,
meters) and a composite score for the four "active" tasks (mental arithmetic,
pattern identification, tracking, problem solving), which involved greater
demand on cognitive resources. Composite scores for Individual tasks were
calculated as follows: For each measure of performance on a task, the raw
scores for al! subjects were converted to standard scores with a mean of 500
and’ a standard deviation of 100. The task composite score for each subject
and experimental treatment was the mean of standard scores on each performance
measurement for that task. The sign of scores was changed, when necessary, so
that higher standard scores always indicated better performance, and lower
scores, poorer performance. Overall, monitoring and active composite scores
were computed by averaging the appropriate task composite scores for each
subject and treatment so that each task made an equal contribution to the
variance. These composite scores are more sensitive to the effects of
experImenta! conditions than are Individual measurements of performance.

Breathalyzer. Breath alcoho! levels were assessed by means of an Omicron
Intoxl lyzer. Practice at using the device was provided the subjects during
performance training. Subjects learned to take a deep breath, remove the
oxygen mask, and breathe into the breath-recording device.


—

those at sea level. While the Impairment of auditory thresholds was greater
at high altitudes than at sea level, performance scores on a "dotting" test
showed “...a great increase In the varlabllity of responses but the average
differences following the alcohol In the mountains compared with sea level
were Insignificant." Actually, performance scores declined with altitude and
with alcohol, but there was no Interaction between the altitude and alcohol
conditions (compared to sea level, scores were 8% and 12% lower for McFarland
at 12,000 and 17,000 ft respectively, before alcohol was ingested; alcohol
Produced a 20% decrement in performance at sea level and, from that base,
scores declined only 6-7% for the two altitude levels). Nevertheless, results
from the blood alcohol values (and perhaps the auditory thresholds) pointed to
significant altitude-alcohol interactions.

McFarland found additional supporting evidence in his 1936 altitude chamber
study with Barach (14). The problem was thoughtfully approached from another
perspective: the oxygen want produced by alcoholic Intoxication was counter-
acted by Inhalation of excess concentrations of oxygen (50%) and carbon
dioxide (2-5%). Subjects exposed to the excess concentration had
significantly lower BAL’s and lactic acid levels than they did when breathing
normal air; subjects given a set of performance tests showed decrements due to
alcohol and most showed Improvement when breathing the increased oxygen/carbon
dioxide. Thus, an Increase of oxygen and carbon dioxide appeared to mitigate
the effects of alcohol by lowering BAL’s and tempering performance decrements.

Finally, McFarland clted the study by Newman (17), In which five subjects
performed at a pursultmeter task In room air and at a simulated altitude of
18,000 ft (by gas mixture, breathed through oxygen masks for a period of about
three min around each testing time). Subjects were given alcohol doses every
30 min and were tested before each dose. The experiment was terminated for
each subject as soon as hls performance score fell five percent. below the
control series value. For three subjects there was a marked reduction of the
blood alcohol concentration at which performance fell significantly when the
low-oxygen mixture was breathed; two subjects showed no significant change.
“Since the low-oxygen mixture alone produced no lowering of performance, and
since the alcohol concentrations at which performance fell off when respiring
this mixture produced no such effect when room air was respired, the
conclusion Is inescapable that the combination of this alcohol concentration
and the low oxygen tension produced what heither was able to do alone." Newman
(17) noted that effects were unlikely to be obtained at altitudes lower than
18,000 ft.

More recent studies suggest a modified conclusion. Higgins and his assoclates
(9) examined alcohol effects under three altitude chamber conditions: ground
level (1287 ft), 12,000 ft, and 20,000 ft (for the latter, a 100% oxygen
mixture was provided via a demand-type regulator system). Subjects received
0, 1.25, or 2.00 cc of 100-proof bourbon per kg of body weight. Several
physlological measures, BAL‘s, and performance scores were obtained. There
were no differential performance effects; the tests thus were relatively
insensitive. At the flow alcohol dose, there were no significant BAL
differences (peaks were about 37 mg %) among the three altitude conditions; at
the higher dose, there were no BAL differences between ground level and the
12,000-ft condition (peak BAL‘s around 95 mg %), but the 20,000-ft condition
ylelded a uniformly higher blood alcoho! curve with a peak around 118 mg %.

13


similiar to those noted above except that altitude had no effect at all on
elther breathalyzer levels or performance.

Finally, in evaluating various types of potential altitude/alcohol effects, It
may be useful to consider the possibly different Influences associated with
(1) acclimitization, (11) fatigue due to physical exertion at altitude, (il})
durations of exposure, (Iv) the sedentary aspects of some conditions (e.g.,
flying as a passenger) or studies, and (v) altitude/humidity (dehydration)
differences between studies.

Altitude. Results from the present study and the other cited alcohot-altitude
studies tend to emphasize the potential for interactive effects. However, the
data also suggest that altitudes around 12,000 ft provide a narrow margin of
safety regarding performance. For example, the present study found no main
effect of altitude on complex performance, but the previous study (4) using
the same performance equipment yielded decrements due to the simulated
altitude. ina different investigation (16), again using the same performance
equipment, subjects performed more poorly at altitude vs. ground level when
sieep deprived for 24 h; with normal sleep, there was no effect of altitude on
thelr performance. Simitarty, In another study (3), tracking performance was
adversely affected by altitude vs ground level conditions during midnight
tests (when subjects were sleepy) but not during the early evening or In the
morning foliowing several hours of sleep. The ground-level "dotting" test
scores reported by McFarland and Forbes (15) were also impaired by altitude
alone at 12,200 feet.

While it Is a truism that effects of any varlable on performance will depend
on the type of performance test, there its considerable Information suggest Ing
that altitudes around 12,000 ft, and perhaps as low as 10,000 ft (5), can
produce performance Impairment In some healthy subjects. Steepiness or sleep
deprivation seems to potentiate those effects (16). Thus, these data support
aeromedical cautions regarding the potential deleterious effects on safety
margins of altitudes In the 10,000-12,000 ft range.

CONCLUSIONS
These results and those of related studies suggest that:

1) BAL‘s are probably not affected by altitudes of 12,000-12,500 ft or
jess.

2) Altitudes of 12,000-12,500 ft appear to have narrow margins of safety
for oxygen-related effects on performance. For some subjects, under
some conditions, altitudes of this level produce performance decrements;
under other conditions, or for other subjects, decrements may not be
evident.

3) Following alcoho! Ingestion, performance at altitudes of 12,000-12,500
ft may show no change compared with ground level.

4) Performance decrements due to alcohol may be Increased by altitudes of
12,000-12,500 ft if subjects are negatively affected by that altitude
without alcohol; the combined effects are then simply additive.

5) Alcohol alone does not appear to potentiate performance decrements at
altitudes of 12,000-12,500 ft, but sleep foss does.

is


AGE, ALCOHOL, AND SIMULATED ALTITUDE:
EFFECTS ON PERFORMANCE AND BREATHALYZER SCORES

Previous research In this laboratory yielded no significant Interactive
effects of alcohol and a simulated altitude of 12,500 feet on either
breathalyzer levels or on complex performance (4). That outcome was contrary
to prevalent beliefs based on early work by McFarland and his associates
(14,15). The present study provided an opportunity to replicate those
findings and to add new Information concerning the possible effects of age as
a factor In the alcohol-altitude-performance equation.

METHOD

Sublects. Twenty-five men, 12 In a 30- to 39-yr age group and 13 In a 60- to
69-yr age group, were subjects. Physiological condition and intellectual
ability were controlled by requiring that subjects pass the equivalent of a
Class 111 airman physical examination, exhibit normal pulmonary function, and
have an intelligence quotient of normal or above as based on two subtests of
the Wechsler Adult Intelligence Scale.

Iask Performance Battery (MTPB). In the Civil Aeromedical
Institute's (CAM!) version of the MTPB, five subjects can be run Independently
at the same time. The MTPB tasks are presented In various combinations to
Produce a synthetic work situation involving varlation of workload and time
sharing of work In assorted tasks. Each subject works at a console that
Incorporates the following tasks:

of warning Jights. These are choice reactlon-time tasks
Involving monitoring of five green lights (normally on) and five red lights
(normally off). Subjects pushed the light/switch whenever a light changed
state. Response times were recorded.

Monitoring of meters. The pointers of four meters constantly moved at
random about the center position. Subjects responded to a shift in mean
Position of a pointer to the left or right of center by pushing a button
under the meter on the side of the deflection. Response times were scored.

Mental arithmetic. Subjects were required to add two 2-digit numbers
presented on a console screen and then mentally subtract a third number
from the sum; answers were recorded with a 10-key pad. Response time and
accuracy were assessed.

Pattern Identification. A standard histogram pattern was displayed ona 6

x 6 cell matrix for 5 s and followed by successive presentations of two
comparison patterns for 3 s each, with 2-s Intervals between patterns.
Subjects pressed an appropriate response button If one, neither, or both of
the comparison patterns matched the standard pattern. Response latency and
accuracy were recorded.

Tracking. The display for the two-dimensional! compensatory tracking task
was an oscilloscope screen. A varying amplitude was Imparted in each


Technical Report Documentation Page

T. Report No. 2. Government Accession No. 3, Recipient's Catalog No.

DOT/FAA/AM-88/2

4, Title and Subtitle 5. Report Date
AGE, ALCOHOL, AND SIMULATED ALTITUDE: EFFECTS ON JANUARY_1988
PERFORMANCE AND BREATHALYZER SCORES 6. Performing Organization Code

8. Performing Organization Report No.

William E. Collins and Henry W. Mertens

9. Performing Organization Nome and Address 10. Work Unit No. (TRATS)
FAA Civil Aeromedical Institute

TT, Contract or Gr

P.O. Box 25082 ontract or Grant No.

Oklahoma City, OK 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name and Address
Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, SW. 14. Sponsoring Agency Code
Washington, D.C. 20591

15. Supplementary Notes

This work was performed vnder tasks AM-A-85/86/87-PSY-94,

16, Abstract

Trained men in two age groups, 30-39 (n=12) and 60-69 (n=13), each performed at
the Multiple Task Performance Battery (MTPB) In four separate fult-day sessions
with and without alcohol (2.2 mL of 100-proof vodka per kg of body weight) at
ground level and at a simulated altitude of 12,500 ft (3810 m). Subjects
breathed appropriate gas mixtures through oxygen masks at both ground level and
altitude. Mean breathalyzer readings peaked near 88 mg % and did not differ
between age groups or altitude conditions. Younger subjects performed better
than older subjects; performance of both age groups was significantly Impaired
by alcohol, but these adverse effects were greater for the older subjects. No
significant effects on performance were obtained due to altitude or to the
Interaction of altitude with alcohol. These results and those from several
other studies suggest that prevalent views regarding the nature of the combined
effects of alcohol and altitude on biood alcohol fevels and on performance need
to be redefined.

17. Key Words 18. Distribution Statement
Age, Alcohol, Altitude, Document is available to the public
Performance through the National Technical

Information Service, Springfield,
Virginia 22161.

19. Security Claasif. (of this report) 20. Security Classif. (of this page) Zi. No. of Pages | 22. Price

Unclassified Unclassified 18

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized



lighter workloads) and the Interaction of age group x workload (p < .001)
(favoring the younger group and lighter workloads); In addition, both alcohot
x time period and age group x alcoho! x time berlod (favoring the placebo
condition, younger subjects, and later time periods) were significant (p <
+01). No significant main effects of altitude or Interaction of altitude with
any other varlable was obtained.

Scores for the individual tasks were subjected to separate analyses (see Table
3) and yle!ded results that were similar to the analyses of composite scores.
Each task showed a significant (p<.01-.001) negative effect of alcohol, but no
Individual task showed an effect of altitude or of an altitude/alcohol
Interaction. There were significant (p<.05-.001) main effects of age group
(favoring the younger subjects) and of workload (favoring lighter workloads)
on scores for each Individual task except pattern § Identification. Time
perlods showed significant (p<.05-.001) differences for the monitoring of
green tights and for arithmetic, pattern Identification, and problem solving,
but not for the monitoring of red lights or of meters, or for tracking.

Workload had a significant main effect In atmost all tasks, as noted above.
Subjects tend to give the three monitoring tasks lower priority compared with
other MTPB tasks that require more active participation. The monitoring
tasks, therefore, generally have secondary status and provide an Index of
residual attention that is related to workload. Fig. 3 Illustrates how
monitoring performance varied as a function of age, alcohol, and workload.
The pattern of monitoring performance in Fig. 3 Indicates that task demands
(workload) were highest (and monitoring performance lowest) in workload
Interval 4, with workload Intervals 5, 2, 3, and 1 following in that order.
The Interaction of age group with workload was statisticaily significant (p
<-001) for the monitoring composite scores as well as for the three Individual
monitoring tasks, but there was no other Interaction of workload in monitor ing
composite scores with any other task. A slight tendency for alcohol effects
on monitoring performance to be greatest at higher workload was not
statistically significant.

Mood Ratings. Mean ratings for attentiveness, energy, tenseness, boredom, and
annoyance are presented in Table 4. Mood results generally did not parallel
performance findings. For all five moods there was a significant (p <
-01-.001) effect of time periods, the result of successively poorer mood
Scores from the first through the third measurement per lod, Irrespective of
the drug or altitude conditions. For atl mood ratings except “tenseness"
there was a significant effect of alcoho! (p < .05-.001); these significantly
Poorer scores for the alcohol (vs. placebo) condition were the only findings
common to both the performance and mood data. For “tlredness" and “boredom
there was a significant age group effect (p < .05-.01), favoring the otder
subjects (who were less tired and less bored). Only five of the 655
interactions yielded significant effects (all at p < .05): for “tenseness",
(age group x time period); for “Irritation", drug x time period; for
“boredom”, drug x attitude; and for “attentiveness”, altitude x time x age
group and altitude x time x drug.

DISCUSSION

«tele AGQ. The older subjects performed significantly more poorly than did the

30-39 year olds on all composite measures of performance and on all the

ell
me


A followup study (10) was conducted in which the ground-level condition was
reptaced by a chamber altitude of 12,000 ft with supplemental oxygen. The low
dose of alcohol again ylelded no differences In peak BAL’s (around 42 mg %) or
In the general coincidence of the BAL time curves. At the higher alcohol
dose, the two 12,000-ft conditions (with and without supplemental oxygen)
ytelded no differences In peak BAL’s (around 111 mg %), but the 20,000-ft
condition (with supplemental oxygen) ylelded a BAL peak around 122 mg %.
Clearly, the BAL peaks reached at 12,000 ft (with or without supplemental
oxygen) were not different from those produced at ground level. With regard
to the 20,000-ft altitude condition, Higgins et ail. (10) proposed that
Increased motility of the gastrointestinal tract caused by the high alcohol
concentratlon combined with Increased motility attributable to the lowered
barometric pressure at 20,000 ft could Increase the absorption rate of the
alcohol with the high dose, thereby producing the higher blood alcoho! levels.

In an alcohol study that focused primarily on several physiological measures,
Lategola, Lyne, and Burr (11) Included an arithmetic test In comparison of
ground-level performance with that at a chamber altitude of 12,000 ft. The
time courses of the BAL curves were virtually identical at ground level and at
altitude with peaks about 91 mg %. Arithmetic scores (errors per minute) were
Impaired by alcohol but did not differ between ground level and altitude
foilowing alcohol Ingestion (performance was actually silghtly better at
12,000 ft).

Collins (3) tralned eight pilots to perform on a two-dimensional tracking task
(joystick control of a localizer/glideslope instrument) while statlonary and
during yaw-axis motion. Tracking scores were obtained at ground level and at
a simulated altitude of 12,000 ft with a placebo and with alcohol. Subjects
performed In the evening, drank until midnight, were retested, slept, and
performed the task again In the morning. Ground-level sessions always
preceded ascent In the altitude chamber. Following alcohol Ingestion (3.25 mL
of 100-proof vodka per kg of body welght), peak breath alcohol levels taken at
ground level averaged 91 mg X. Alcohol by Itself caused performance
deterioration, and altitude by Itself Impaired performance only during the
midnight sessions when subjects were sleepy, but no significant
altitude/alcohol Interactions on performance (and no hangover effects) were
obtained.

To follow up on these resuits, Collins, Mertens, and Higgins (4) trained
subjects to perform on the MTPB in four sessions over a 2-week period. The
four sessions were ground level (approximately 1,300 ft) and altitude (12,500
ft) both with and without alcohol (2.2 cc of 100-proof Smirnoff vodka per kg
of body welght). Subjects breathed appropriate gas mixtures through oxygen
masks at both ground level and altitude. Results showed no differential
effect of simulated altitude on breathalyzer readings (peaks averaged .078% at
12,500-ft and .077% at ground level). The best performance occurred at ground
fevel under placebo conditions; the 12,500-ft simulated altitude produced some
decrement for the placebo condition scores. Afcoho! at ground level resulted
in significantly impalred performance during the first three hours after
drinking; the addition of aititude to the alcohol condition further depressed
performance scores, but to about the same extent that placebo scores were
depressed by altitude. Thus, there was no effect of altitude on breathalyzer
readings and a simple additive effect of alcohol and altitude decrements on
performance scores. Results of the present study, for both age groups, were

14