Kinuhata et al. Asia Pac Fam Med (2018) 17:6
https://doi.org/10.1186/s12930-018-0043-0

Asia Pacific Family Medicine
Open Access

RESEARCH

The 1‑min animal test as a mental status
screening examination in patients with diabetes
Shigeki Kinuhata1, Yasuhiko Takemoto1*, Mariko Senda2, Shiho Nakai2, Erika Tsumura2, Tatsuyuki Otoshi2,
Sadahiko Hiratani2, Kazuo Fukumoto1, Hiroki Namikawa1, Yoshihiro Tochino1, Mina Morimura1, Taichi Shuto1
and Sadahiko Uchimoto2

Abstract
Background: Detecting and treating dementia at an early stage are important. Although the Revised Hasegawa
Dementia Scale (HDS-R) is commonly used to detect dementia, it takes about 10 min to complete. In contrast, the1-min animal test (OMAT) takes only 1 min to complete and may be a helpful screening test for general practitioners
in deciding whether to proceed with administering further diagnostic tests such as the HDS-R. We sought to examine the relationship between the OMAT and HDS-R scores, and determine the cut-off OMAT score that balanced thesensitivity and specificity in identifying HDS-R-positive patients.
Methods: A total of 122 consecutive patients with diabetes who visited the outpatient clinic at the Fujiidera Municipal Hospital were enrolled. The patients underwent the OMAT and HDS-R on the same day. Tests were conducted in asingle-blinded manner. The relationship between the OMAT and HDS-R scores was examined using Spearman’s rankcorrelation. Receiver operating characteristic curve analysis was performed to identify the optimal cut-off score of
OMAT that will determine whether to proceed with further diagnostic tests.
Results: A strong positive correlation between the OMAT and HDS-R scores was observed (r = 0.70). The sensitivity
and specificity of OMAT using cut-off scores of 12/13, 13/14, and 14/15 for HDS-R-positive patients were 0.87 and 0.66,
1.00 and 0.51, and 1.00 and 0.40, respectively among all the subjects. Similar results were obtained in a subgroup of
subjects aged ≥ 65 years.
Conclusions: A cut-off score of 13/14 on the OMAT balanced the sensitivity closest to 1.00 and allowed for the highest specificity for the HDS-R not only among all the patients, but also among just the patients aged ≥ 65 years. The
OMAT may be an optimal screening test to determine whether to proceed with further diagnosis using HDS-R.
Trial registration UMIN UMIN000025260. This study is retrospectively registered on December 13th, 2016
Keywords: 1-min mental status examination, 1-min animal test, Dementia, Revised Hasegawa Dementia Scale,
Screening*Correspondence: m2625696@med.osaka‑cu.ac.jp
1
Department of Medical Education and General Practice, Osaka City
University Graduate School and Faculty of Medicine, 1‑4‑3, Asahi‑machi,
Abeno‑ku, Osaka 545‑8585, Japan
Full list of author information is available at the end of the article© The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License(http://creat​iveco​mmons​.org/licen​ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium,provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license,
and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creat​iveco​mmons​.org/
publi​cdoma​in/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Kinuhata et al. Asia Pac Fam Med (2018) 17:6

Background
It has been estimated that one-seventh of elderly people
aged 65 years or greater suffer from dementia in Japan[1]. Ohara et al. have shown that diabetes is a significant
risk factor for all-cause dementia [2]. In addition, theprevalence of Alzheimer’s disease (AD), one of the leading causes of dementia, is on the rise [3]. Dementia is
one of the leading sources of caregiver burden and has
emerged as a crucial public health, medical, economic,
and social problem.
Several approaches to treat dementia including personcentered care, rehabilitation, training, or drugs, haverecently become clinically available to prevent the progression of dementia. Therefore, it is important to perform screening tests for dementia at an early stage so thatpatients with dementia can be treated as early as possible
to avert the progression of dementia-related behaviors
and symptoms, and reduce medical, economic, and social
burden alike. However, the early symptoms of dementia
are difficult to detect for not only the patients and theirfamilies, but also for general practitioners. In addition, it
takes about 10 min to complete the frequently used tests
such as the Revised Hasegawa Dementia Scale (HDS-R)[4, 5] or the Mini-Mental State Examination (MMSE) [6],which is often difficult to spare in busy out-patient clinical settings.
Recently, the 1-min animal test (OMAT), which is a
1-min mental status examination using animal names
measuring verbal category fluency, has been developed.
Verbal fluency can be classified into category fluency andletter fluency. Previous studies have shown that category
fluency tasks are better at discriminating between control subjects and patients with dementia or mild cognitive impairment, when compared with letter fluency[7–9]. Moreover, the category “animals” is more appropriate than “vegetables” to measure semantic category
fluency because it is not confounded by sex-related differences [10]. Therefore, we decided to use the OMAT.
Previous studies have validated the relationship between
the OMAT and MMSE and demonstrated a positive correlation between OMAT and MMSE scores [7, 10, 11].
However, to the best of our knowledge, there has been
no investigation into an association between the OMATand HDS-R scores. The OMAT may be a helpful screening test for general practitioners in deciding whether toproceed with administering further diagnostic tests suchas the HDS-R.
We sought to examine the relationship between the
OMAT and HDS-R scores, and also the cut-off score of
OMAT that balanced the sensitivity closest to 1.00 andenabled the highest specificity for the HDS-R-positive
status; this would help us determine whether to proceedwith administering the HDS-R in all consecutive patients

Page 2 of 5with diabetes as well as in just the diabetic patients aged
65 years or older.

Methods
A total of 122 consecutive patients with diabetes who
visited the outpatient clinic at Fujiidera Municipal Hospital from January 2014 to June 2015 were enrolled in thisstudy. A diabetologist working at the hospital administered the OMAT and HDS-R tests. Tests were conductedin a single-blinded manner on the same day. The study
protocols were in accordance with the Declaration of
Helsinki, and were approved by the ethics committee of
the Osaka City University (number 3496). Informed consent was obtained from all the subjects or their close relatives prior to participation.
1‑min animal test

The OMAT is a quick and simple examination for category fluency that asks subjects to list as many different
animals as possible in 1 min [7, 12]. A previous report
has shown that a cut-off score of 13/14 on the OMAT
was able to distinguish patients with AD from control
subjects with a sensitivity of 0.91 and a specificity of 0.81.
The number of animal names that could be verbally generated by the subjects was measured in this study.
Revised Hasegawa Dementia Scale

The HDS-R has been established in Japan and, like the
MMSE, is used as a common diagnostic test for dementia; the HDS-R has been demonstrated to be diagnostically more accurate compared to the MMSE [13]. The
HDS-R consists of 9 simple questions with a maximum
score of 30 points. Subjects are asked to state their age,date, place, repeat 3 words, perform serial subtraction of
7 starting at 100, recall digits backwards, recall 3 words,
recall 5 objects, and state the names of vegetables [5].
The number of correct answers was measured and converted into scores based on the HDS-R assessment scale.
A score of 20/21 on the HDS-R has been shown to discriminate between normal cognition and dementia witha sensitivity of 0.90 and a specificity of 0.82. Therefore,
patients who scored less than 21 were defined as HDS-Rpositive in this study.
Relationship between OMAT and HDS‑R

In this study, we enrolled all consecutive patients withdiabetes who visited our hospital from January 2014 toJune 2015. However, the prevalence of dementia in Japan
has been reported to be 0.0476% among individuals
younger than 65 years of age, and 15.75% among individuals who are 65 years or older [1]. Therefore, we examined the correlation between the OMAT and HDS-R
scores, as well as the OMAT cut-off score to determineKinuhata et al. Asia Pac Fam Med (2018) 17:6

Page 3 of 5

whether to proceed with administering the HDS-R, notonly among all the patients but also in a subgroup ofpatients aged 65 years or greater.
Statistical analysis

The Spearman’s rank correlation coefficient was used
to determine the correlation between the OMAT and
HDS-R scores. The receiver operating characteristics(ROC) curve analysis was used to determine the OMAT
cut-off score that could identify HDS-R-positive patients[14]. The cut-off score was defined as that balancing thesensitivity closest to 1.00 while enabling the highest specificity on the ROC curve in order for the OMAT to be an
optimal screening test in deciding whether to proceed toadministering the HDS-R. Results with p values less than
0.05 were considered statistically significant. The statistical analyses were performed using IBM SPSS 22.0 (Chicago, IL, USA).

Results
The baseline characteristics of the 122 subjects used forthe analysis are shown in Table 1. We enrolled 122 consecutive patients with diabetes who visited the outpatient
clinic at the Fujiidera Municipal Hospital in this study.
The age range of the study subjects was 40–89 years. The
analyses were repeated in a subgroup of patients who
were 65 years or older (n = 93; median age 75 years; interquartile range 70–80 years).
Figure 1 displays the relationship between the OMATand HDS-R scores. A strong positive correlation wasobserved between the OMAT and HDS-R scores(r = 0.70, p < 0.01).
Figure 2 displays the results of the ROC curve analysis
to determine the optimal OMAT cut-off score that canidentify HDS-R-positive individuals. The OMAT scoresof 12/13, 13/14, and 14/15 identified HDS-R-positive
patients with sensitivities of 0.87 (0.70–0.96; 95% CI,
confidence intervals), 1.00 (0.84–1.00; 95% CI), and 1.00
(0.84–1.00; 95% CI), and with specificities of 0.66 (0.55–
0.76; 95% CI), 0.51 (0.40–0.61; 95% CI), and 0.40 (0.30–
0.50; 95% CI), respectively. Hence, the OMAT score of

Table 1 Baseline characteristics of the study sample(N = 122)
VariableMen/women, n/n

63/59

Age (years)a72 (65–78)

1-min animal test ­scorea

13 (10–16)

Revised Hasegawa’s dementia scale ­scorea

25 (20–28)

N total study sample size, n number of males/females in groupa

Values are expressed as median (interquartile range)

Fig. 1 Relationship between the 1-min animal test and Revised
Hasegawa Dementia Scale scores. n = 31, the number of patientswith the 1-min animal test score < 14 and Revised Hasegawa’s
dementia scale score < 21. n = 0, the number of patients with the
1-min animal test score ≥ 14 and Revised Hasegawa’s dementia scalescore < 21. n = 45, the number of patients with the 1-min animal testscore < 14 and Revised Hasegawa’s dementia scale score ≥ 21. n = 46,
the number of patients with the 1-min animal test score ≥ 14 andRevised Hasegawa’s dementia scale score ≥ 21. r = 0.70 (Spearman’srank correlation), p < 0.01

13/14 was able to balance the sensitivity closest to 1.00
while enabling the highest specificity in identifying HDSR-positive patients.
A strong positive correlation was observed between the
OMAT and HDS-R scores (r = 0.62; p < 0.01) in the subgroup analysis as well. The ROC curve analysis showedthat the OMAT scores of 12/13, 13/14, and 14/15 wereable to identify HDS-R-positive patients with sensitivities
of 0.87 (0.69–0.96; 95% CI), 1.00 (0.83–1.00; 95% CI), and
1.00 (0.83–1.00; 95% CI), and with specificities of 0.56
(0.43–0.68; 95% CI), 0.35 (0.23–0.48; 95% CI), and 0.25
(0.15–0.38; 95% CI), respectively. Therefore, an OMAT
score of 13/14 balanced the sensitivity closest to 1.00
while enabling the highest specificity in identifying HDSR-positive patients among subjects who were 65 years orolder.

Discussion
In the present study, a strong positive correlation wasobserved between the OMAT and HDS-R scores among
all the enrolled patients with diabetes between 40 and
89 years of age. In addition, the OMAT cut-off scoreof 13/14 balanced the sensitivity closest to 1.00 while
enabling the highest specificity in identifying HDS-Rpositive patients to determine whether to proceed with

Kinuhata et al. Asia Pac Fam Med (2018) 17:6

Fig. 2 Receiver operating characteristic curve analysis. The receiver
operating characteristic curve analysis of the 1-min animal test for the
cut-off score of 20/21 on the Revised Hasegawa’s Dementia Scale

administering the HDS-R among all the patients as wellas in the subgroup of patients who were 65 years or older.
To our knowledge, ours is the first study to evaluate theassociation between OMAT and HDS-R and show a positive correlation between their scores.
Although the MMSE has been commonly used as ascreening test for dementia all over the world, it has several disadvantages. The assessment of dementia status by
MMSE is prone to be influenced by the educational levelof the subjects [15]. Executive functions are not fully represented in the MMSE. In addition, a previous study has
shown that the HDS-R had a higher area under the ROC
curve than the MMSE while identifying patients with AD[13]. Therefore, it would be useful to apply HDS-R as astandard examination in the present study.
Though HDS-R has been established as a common
diagnostic test for dementia, it consists of 9 questions,takes approximately 10 min to complete, and is occasionally difficult to implement in busy out-patient clinical settings. Meanwhile, OMAT consists of one simple
question and is executed in 1 min. We found that the
OMAT cut-off score of 13/14 showed a sensitivity of 1.00
for identifying HDS-R-positive patients in this study.
This indicates that all the patients with a score of 14 ormore on the OMAT scored 21 or higher on the HDS-R,
and that the HDS-R was negative for dementia when the
OMAT was negative for dementia. Therefore, the OMAT
can be considered as an optimal screening test to determine whether to proceed with the administration of further diagnostic tests, such as the HDS-R. In addition, aPage 4 of 5score of 13/14 was the common cut-off score to identify
HDS-R-positive patients between both age groups tested,
and thus may be a widely applicable index.
There have been no previous studies comparing the difference between implementing the OMAT in Japaneseand any other language. The OMAT requires subjects tolist as many different animals as possible in 1 min; therefore, we speculate that any differences are unlikely. Further investigations are needed to confirm this.
The present study has some limitations. First, the possibility of dementia was considered based on the HDS-R
score alone, and no other tests were administered to validate this assumption. The gold standards for the diagnosis of dementia are the ICD-10, NIA-AA, and DSM-5
tests. Second, the HDS-R is an examination to assess
the presence or absence of cognitive dysfunction, inparticular, memory. It does not to distinguish between
the different types of dementia. The OMAT is a simple
examination to assess the presence or absence of cognitive dysfunction. We did not examine the association
between the different types of dementia and the resultsof the HDS-R or the OMAT in this study. To the best of
our knowledge, no previous studies have examined theseassociations. Further studies are necessary to address
this issue. Third, the subjects of the present study were
all Japanese patients with diabetes from a single hospital. Further studies involving non-diabetic patients or
subjects of other ethnicities are required to improve thevalidity of our results. Fourth, the tests were conductedin a single-blinded manner. Further examinations using
a double-blinded and independent study design are warranted to confirm our findings.

Conclusions
The present study showed a strong positive correlation
between the OMAT and HDS-R scores. The OMAT cutoff score of 13/14 balanced the sensitivity closest to 1.00
while enabling the highest specificity in the identificationof HDS-R-positive patients. The OMAT may be used as
an optimal screening test while deciding whether to proceed with administering further diagnostic tests such as
the HDS-R not only among all the patients enrolled in
the study, but also in just the subgroup of patients aged
65 years or older.
Authors’ contributions
SK participated in the study design and statistical analysis. ET, KF, HN, and SU
collected the data. MS, SN, TO, SH, and SU participated in the study design. YT,
YT, MM, and TS helped draft the manuscript. All authors read and approved
the final manuscript.
Author details
1
Department of Medical Education and General Practice, Osaka City University Graduate School and Faculty of Medicine, 1‑4‑3, Asahi‑machi, Abeno‑ku,
Osaka 545‑8585, Japan. 2 Fujiidera Municipal Hospital, Fujiidera, Japan.

Kinuhata et al. Asia Pac Fam Med (2018) 17:6

Page 5 of 5

Acknowledgements
Not applicable.

4.

Competing interests
The authors declare that they have no competing interests.

5.

Availability of data and materials
The datasets used and/or analyzed during the current study available from thecorresponding author on reasonable request.

6.

Consent for publication
Not applicable.
Ethics approval and consent to participate
The study protocols were in accordance with the Declaration of Helsinki, andwere approved by the ethics committee of the Osaka City University (number
3496). Informed consent was obtained from all the subjects or their close relatives prior to participation.
Funding
This was not an industry-supported study.

7.
8.
9.
10.
11.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Received: 20 December 2016 Accepted: 30 May 2018

12.
13.

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