X. Fu1,*, W. Yu2,*, M. Ke2, X. Wang1, J. Zhang1, T. Luo1, P.J. Massman3,4, R.S. Doody3, Y. Lü1,*
1. Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; 2. Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China; 3. Department of Neurology, Baylor College of Medicine, Houston, TX USA at the time this work was done. Now Genentech/Roche, Basel, Switzerland; 4. Department of Psychology, University of Houston, Houston, TX USA; *Authors contributed equally and are co-first authors of the study.
Corresponding Authors: Prof. Yang Lü, 1 Youyi Road, Yuzhong District, Chongqing 400016, China, Tel: +86-23-89011622, Fax: +86-23-68811487, E-mail: email@example.com
J Prev Alz Dis 2020;
Published online December 21, 2020, http://dx.doi.org/10.14283/jpad.2020.72
BACKGROUND: A specialized instrument for assessing the cognition of patients with severe Alzheimer’s disease (AD) is needed in China.
Objectives: To validate the Chinese version of the Baylor Profound Mental Status Examination (BPMSE-Ch).
Design: The BPMSE is a simplified scale which has proved to be a reliable and valid tool for evaluating patients with moderate to severe AD, it is worthwhile to extend the use of it to Chinese patients with AD.
Setting: Patients were assessed from the Memory Clinic Outpatient.
Participants: All participants were diagnosed as having probable AD by assessment.
Measurements: The BPMSE was translated into Chinese and back translated. The BPMSE-Ch was administered to 102 AD patients with a Mini-Mental State Examination (MMSE) score below 17. We assessed the internal consistency, reliability, and construct validity between the BPMSE-Ch and MMSE, Severe Impairment Battery (SIB), Global Deterioration Scale (GDS-1), Geriatric Depression Scale(GDS-2), Instrumental Activities of Daily Living (IADL), Physical Self-Maintenance Scale (PSMS), Neuropsychiatric Inventory (NPI) and Clinical Dementia Rating (CDR).
Results: The BPMSE-Ch showed good internal consistency (α = 0.87); inter-rater and test-retest reliability were both excellent, ranging from 0.91 to 0.99. The construct validity of the measure was also supported by significant correlations with MMSE, SIB. Moreover, as expected, the BMPSE-Ch had a lower floor effect than the MMSE, but a ceiling effect existed for patients with MMSE scores above 11.
Conclusions: The BPMSE-Ch is a reliable and valid tool for evaluating cognitive function in Chinese patients with severe AD.
Key words: Alzheimer’s disease, Baylor Profound Mental Status Examination, Chinese version, severe dementia, validation.
Abbreviations: AD: Alzheimer’s disease; ADAS-cog: Alzheimer’s Disease Assessment Scale-Cognitive section; ANOVA: A one-way analysis of variance; BPMSE: Baylor Profound Mental Status Examination; BPMSE-Ch: Chinese version of the Baylor Profound Mental Status Examination; BPMSE-Ch-cog: Cognition subscale of Chinese version of the Baylor Profound Mental Status Examination; BPMSE-Ch-behav: Behavior subscale of Chinese version of the Baylor Profound Mental Status Examination; CDR: Clinical Dementia Rating; FAST: Functional Assessment Staging; GDS-1: Global Deterioration Scale; GDS-2: Geriatric Depression Scale: IADL, Instrumental Activities of Daily Living; MMSE: Mini-Mental State Examination; NPI: Neuropsychiatric Inventory; PSMS: physical self-maintenance scale; SIB: Severe Impairment Battery.
Alzheimer’s disease (AD) is a common neurodegenerative disorder among mainly elderly persons worldwide. The manifestations of AD include deterioration in cognition, memory and activities of daily living. It is usually accompanied by behavioral and psychological symptoms (1).
Currently, China is facing serious issues related to having an aging population. Persons aged 60 or older account for 17.3% of the total population (2). The prevalence of all-cause dementia over age 65 is about 6% in China, and AD makes up about 65% of all cases (3, 4). The rough prevalence of AD in China has reported to ranges from 7 per 1000 people to 66 per 1000 individuals (5). In a population-based cross-sectional survey, 10276 residents aged 65 year or older were drawn from Beijing (northern-eastern), Zhengzhou (northern-central), Guiyang (southern-western) and Guangzhou (southern-eastern). This survey showed that the prevalence of AD was 3.21% in a total of 10276 residents (6). Despite the fact that China has the relatively high AD prevalence, few studies of AD were conducted to research excellent methods for AD diagnosing and evaluating.
It seems unquestionable that AD is gradually evolving into a crucial social problem and presents a major challenge for health-care in China. However, awareness of AD and dementia in general is inadequate in China, leading to delayed diagnosis and initiation of treatment (7, 8).Therefore, many patients do not get evaluated until moderate to severe stages of the disease (9, 10). Moreover, once these patients present for an evaluation, tools to assess them are limited (11). Hence, better instruments are needed for the accurate assessment of patients with advanced AD.
A variety of neuropsychological and functional measures have been utilized to assess mental status and dementia severity both cross-sectionally and longitudinally. Frequently-used instruments include the Mini-Mental Status Examination (MMSE) (12), Severe Impairment Battery (SIB) (13), Alzheimer’s Disease Assessment Scale-Cognitive section (ADAS-Cog) (14), Geriatric Deterioration Scale (GDS-1) (15), Functional Assessment Staging Tool(FAST) (16) and Clinical Dementia Rating (CDR) (17). However, these scales show some limitations in patients with moderate to severe AD. The MMSE and ADAS-cog are not optimal for evaluating patients with severe AD because both contain a lot of verbal information and; therefore, the results may be confounded by language disorders and/or low level of education. SIB is a suitable tool to evaluate patients with severe dementia. However, this test takes more than 30 minutes to administer, which often exceeds the attention capacity of most patients with severe AD (18). The NPI is usually used to evaluate neuropsychiatric symptoms, but it is largely dependent on the description from caregivers (19). Overall, it is clear that a convenient and effective assessment instrument for measuring cognitive function in patients with severe AD is highly needed.
The Baylor Profound Mental State Examination (BPMSE) developed by Doody RS et al, is a simplified scale which has proved to be a reliable and valid tool for evaluating patients with moderate to severe AD (20). And in Doody’s study, European American accounted for about 82% of the original population. Thus, it is worthwhile to extend the use of the BPMSE to Severely demented patients from different cultural backgrounds. To date, there have been three translated versionsof the BPMSE, including Korean, Danish and Spanish (21-23). A study of the Korean version has shown that the BPMSE is a rapid, easy and valid scale for measuring cognitive function in patients with moderate to severe AD, particularly in patients with MMSE below 12. Similarly, a study utilizing the Danish version indicated that the BPMSE is a stable and strong instrument, and was recommended as an appropriate measure of dementia severity in patients with more sever impairment. Adaptation of the Spanish version revealed that BPMSE that the BPMSE is a useful tool for assessing cognitive function, even in daily medical practice focusing on patients with severe AD.
In China, there is no applicable scale for assessing patients with severe AD. Therefore, the aim of our study was to develop a Chinese version of the BPMSE (BPMSE-Ch) and to evaluate the psychometric properties of this version in Chinese patients with AD.
The original version of BPMSE consists of three parts, including the cognition subscale which includes 25 questions, the behavior subscale which includes 10 items to rate the presence or absence of behavioral problems, and 2 qualitative observations of language and social interaction. The cognition subscale assesses four areas: language, orientation, attention, and motor skills. The BPMSE total cognition subscale has a score between 0and 25: maximum 5 scores for orientation, 11 scores for language, 4scores for attention and 5 scores for motor skills. BPMSE behavior subscale score has a score between 0 (no behavioral disturbances) and 10 (all behavioral disturbances). In present study, we did not study the 2 qualitative observations about communication and social interactions.
Firstly, the original version of BPMSE was translated into Chinese with Mandarin by two bilingual translators whose mother tongue was Chinese. Then, the two Chinese versions were discussed by our team with gerontologists, a neurologist, a psychologist and an English expert, and the final Chinese version was formulated based on this input. Finally, two other translators of English philology back translated the final Chinese version into English to confirm consistency with the original version.
Patients were recruited from the Memory Clinic, Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University.
(a) All participants were diagnosed as having probable AD according to National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer’s Disease and Related Disorders Association criteria (NINCDS-ADRDA) (24); (b) Patients with MMSE <17 were included; (c) This study was approved by the Ethical Committee of The First Affiliated Hospital of Chongqing Medical University on human research; (d) Informed consent was obtained from all participants or their family members.
(a) Patients were excluded if they had other neurological or psychiatric disorders or clinically significant medical conditions (e.g., acute infections, cancer, organ failure etc.,); (b) Patients had severely impaired communication abilities (e.g., global aphasia, deafness, blindness, muteness etc.,); (c) Patients had a history of head trauma, sedative drugs use or substance abuse.
The following measures were administered to all enrolled patients: BPMSE-Ch, MMSE, SIB, GDS-1, GDS-2, IADL, PSMS, NPI, and CDR. All tests were given on the same day. Two trained physicians in our clinic administered the BPMSE-Ch to evaluate a subset of enrolled patients consecutively and independently in order to examine inter-rater reliability. Finally, to investigate test-retest reliability, some patients were randomly chosen to be given the BPMSE-Cha second time within 30days of the first administration. It took 5 minutes on average to administer the BPMSE-Ch.
Internal consistency was assessed by computing coefficient α. Inter-rater reliability was assessed by correlation and paired t-test of the two scores obtained by different professionals on the same day. And the test-retest reliability was also calculated with correlational and paired t-test analyses using scores obtained on the same patient within 30 days. The correlations between the BPMSE-Ch and other measures including the SIB, MMSE, GDS-1, GDS-2, IADL, PSMS, NPI and CDR were calculated with Pearson correlations in order to evaluate construct validity. In addition, patients were divided into dementia severity groups using the MMSE and CDR, and differences between those groups were analyzed by conducting a one-way analysis of variance (ANOVA) and Scheffé’s test. Statistical analyses were performed with SPSS 20.0 for Windows.
Demographic characteristics and test performances
102 patients (male: 35, female: 67) were included in our study, the mean age of the patients was 77.76, ranging between 64 and 93. The mean years of education was 7.95, ranging from 0 to 16 years. The specific variations were showed in Table 1.
Abbreviations: MMSE, Mini-Mental State Examination; BPMSE-Ch-cog, Cognition subscale of Chinse version of the Baylor Profound Mental Status Examination; BPMSE-Ch-behav, Behavior subscale of Chinse version of the Baylor Profound Mental Status Examination; SIB, Severe Impairment Battery; NPI, Neuropsychiatric Inventory; SD, standard deviation.
In our study, the coefficient α which could reflect the inter-correlations for items on the BPMSE-Ch cognition (BPMSE-Ch-cog) subscale, was 0.87. Furthermore, significant correlations were found among all the BPMSE-Ch-cog components, as seen in Table 2. Inter-rater and test-retest reliability were showed in Table 3.
Correlation coefficients by Pearson correlation. * p< 0.001.
Abbreviations: BPMSE-Ch-cog, Cognition subscale of Chinse version of the Baylor Profound Mental Status Examination; BPMSE-Ch-behav, Behavior subscale of Chinse version of the Baylor Profound Mental Status Examination.
Correlation coefficients by Pearson correlation. n = Number of patients. All p values <0.001.
52 patients were tested twice by two trained doctors simultaneously and independently to determine the inter-rater reliability. The correlation between two total cognition subscale scores was 0.99 (p < 0.001) and there was no significant difference (paired t (51) = +1.84, p > 0.05) between the two scores (Mean = 0.17, SD = 0.68). The correlation between two behavior subscale scores was 0.92 (p < 0.001).
42 patients were tested twice by a same doctor within 30 day-interval for the test-retest reliability. The test-retest correlation between two total cognition scores was 0.99 (p < 0.001). Similarly, there was no significant difference (paired t (41) = +1.18, p > 0.05) between the two scores obtained at two time points (Mean = 0.14, SD = 0.78). The test-retest correlation between two behavior scores was 0.94 (p < 0.001).
Construct validity of the BPMSE-Ch was showed in Table 4. The correlations between the BPMSE-Ch-cog and MMSE (0.76), SIB (0.78), GDS-1 (-0.26), GDS-2 (0.16), PSMS (-0.26), IADL (-0.36), NPI (-0.41), CDR (-0.54) were calculated by Pearson correlation. The results showed that the construct validity of BPMSE-cog was very good (r=0.78) for SIB and good for MMSE (0.76). In addition, the relationship between BPMSE-Ch behavior subscale (BPMSE-Ch-behav) and NPI was analyzed (0.54, p < 0.001, Table 4).
Abbreviations: BPMSE-Ch, Chinse version of the Baylor Profound Mental Status Examination; BPMSE-Ch-cog, Cognition subscale of Chinse version of the Baylor Profound Mental Status Examination; BPMSE-Ch-behav, Behavior subscale of Chinse version of the Baylor Profound Mental Status Examination; MMSE, Mini-Mental State Examination; SIB, Severe Impairment Battery; GDS1, Global Deterioration Scale; GDS2, Geriatric Depression Scale; IADL, Instrumental Activities of Daily Living; PSMS, physical self-maintenance scale; CDR, Clinical Dementia Rating; NPI, Neuropsychiatric Inventory.
Ceiling and floor effects
The relationship between BPMSE-Ch-cog and MMSE was revealed on a scatterplot (Supplementary Figure 1A). The range of 0 to 5 scores on the MMSE corresponded to a substantial range of 2 to 24 scores on BPMSE-Ch-cog, indicating that the BPMSE-Ch had no floor effect. In addition, it was found that patients scoring 12 to 16 on MMSE had the BPMSE-Ch-cog scores ranging from 20 to 25 (Mean: 23.08, SD: 1.08, Table 5). This demonstrated that BPMSE-Ch showed a ceiling effect among patients who were at a relative moderate level of dementia.
The relationship between BPMSE-Ch-cog and SIB scores is displayed (Supplementary Figure 1B). The relatively highR2=0.61 indicated that BPMSE-Ch-cog showed a strong association with the SIB, which demonstrated that the BPMSE-Ch was a sensitive tool for assessing patients with severe AD.
BPMSE-Ch-cog score stratified by MMSE levels
Table 5 presented that BPMSE-Ch-cog differentiated all the enrolled patients belonging to different severity groups according to the MMSE scores (F = 56.7, p <0.001). Patients in the MMSE Group 1 (range 16-12) had a BPMSE-Ch score of 23.08 ± 1.08, patients in the MMSE Group 2 (range 7-11) had a BPMSE-Ch score of 21.25 ± 3.53, and patients in the MMSE Group 3 (range 0-6) had a further reduced BPMSE-Ch score of 12.50 ± 6.69. From the results of Table 5, it was found that the differences in total BPMSE-Ch-cog score as well as in its four subcomponents scores between the Group 2 and Group 3 was significant (p < 0.001).
Abbreviations: MMSE, Mini-Mental State Examination; BPMSE-Ch-cog, Cognition subscale of Chinse version of the Baylor Profound Mental Status Examination; SD, standard deviation; n = Number of patients. One-way ANOVA test. NS = Nonsignificant; 1. By Scheffé’s analysis
BPMSE-Ch-cog score stratified by CDR levels
BPMSE-Ch-cog differentiates the patients into different groups according to the CDR stage (F = 16.0, p < 0.001) (Supplementary Table 1). It was observed that the mean BPMSE-Ch-cog and subcomponents scores declined as the CDR stage increased (Supplementary Table 1). Furthermore, at Group 1 (CDR = 0.5), the total score of BPMSE-Ch-cog ranged from 23 to 25(Mean = 24.33, SD = 1.15); at Group 2 (CDR = 1), the total score of BPMSE-Ch-cog ranged from 19 to 25 (Mean = 22.86, SD = 1.42); at Group 3 (CDR = 2), the total BPMSE-Ch-cog score ranged from 2 to 25 (Mean = 19.82, SD = 5.59); at Group 4 (CDR = 3), the total BPMSE-Ch-cog score ranged from 2 to 24 (Mean = 12.50, SD = 7.29). It was observed that as the CDR stage increased, the corresponding range of BPMSE-Ch-cog became wide. Moreover, it was also shown that significant differences of total BPMSE-Ch-cog score and subcomponents scores existed between Group 3 and Group 4(Supplementary Table 1). All above suggested that BPMSE-Ch measured in a way different from CDR, and could differentiate levels of cognition at high CDR stages. Discussion The present study shows that BPMSE-Ch is a reliable, stable and valid instrument for assessing cognition in patients with severe AD. Internal consistency is robust, inter-rater reliability is near-perfect for both the BPMSE-Ch-cog and BPMSE-Ch-behav subscales, and test-retest reliability is also excellent. Furthermore, excellent construct validity was found referring to significant correlations with SIB (r=0.78), MMSE (r=0.76). These findings are consistent with the results of previous adoptions of Korean, Spanish, and Danish versions of the BPMSE. BPMSE-Ch-cog scores were strongly associated with MMSE, SIB ratings, indicating that the BPMSE-Ch-cog can differentiate well among patients with AD with differing degrees of cognitive impairment, particularly in the more severe end of the dementia spectrum, which of course is its primary intended use. In this regard, BPMSE-Ch-cog do not display floor effects in severely demented patients, as measured by the MMSE. Also, BPMSE-Ch-cog scores are strongly associated with SIB scores (while displaying a lower floor than the SIB), and its administration time is much shorter (only 5 minutes on average versus 30 minutes for the SIB). It further suggests that BPMSE-Ch is an efficient tool. Relative low correlations are also shown between BPMSE-Ch-cog scores and PSMS and IADL functional scores, demonstrating that the BPMSE-Ch can only partly measure cognitive abilities relevant to the abilities needed to function in daily life. We thought the possible reason is that the most enrolled patients would have reached maximum impairment of activities of daily living. It supposed that a certain degree of ceiling effects existed in IADL and PSMS tests. AlthoughGDS-1 is an available tool used to evaluate not only cognition but also the abilities to maintain daily life, participation in adverse activities and it is useful for the severe AD cases (25-27), it is a synthetic grade evaluation tool. The forced-choice format would place most enrolled patients into high stages. This might be the reason that the correlation between BPMSE-Ch and GDS-1 is low. Behavioral and psychological symptoms of dementia (BPSD) in patients with Alzheimer’s disease have a strong correlation with cognitive impairment and impairment in activities of daily living. NPI is a common tool for BPMSD evaluating. The BPMSE-Ch-behav selectively focused on disruptive behaviors. In this study, it has been found that there is a moderate correlation between BPMSE-Ch-behavand NPI. While the NPI is obtained by questions to the primary caregiver and is a complex and time-consuming process. Therefore, it indicated that BPMSE-Ch is also a relative practicable instrument to evaluate the behavioral and psychological symptoms in patients with severe dementia. The correlation between BPMSE-Ch-cog and GDS-2 is not significant (r = 0.16, p > 0.001). There are two possible reasons. Firstly, BPMSE-Ch-cog does not involve questions directed against depressive symptoms and is not intended to evaluate for depression. Secondly, it has been reported that patients with moderate-severe AD have relatively low GDS-2 scores (28), which is similar to our study. It suggests that patients with moderate-severe AD have no obvious depression symptoms. In our study, the highest GDS-2score seen was 24; therefore, GDS-2 sometimes shows a good complementary assessment for depression. Because the BPMSE measures clinical features distinct from the GDS-2 the absence of correlation is not surprising.
Regarding its suitability for use with severely impaired patients, it has been observed that the BPMSE-Ch-cog differentiates well between patients with MMSE scores 0-6 and those with MMSE scores 7-11, but not as well between patients with scores of 12-16 and those with scores 7-11. This indicates that the BPMSE-Ch, like its versions in other languages, is most appropriate to use with patients who are more severely impaired (with MMSE score of 11 or below). Similarly, analyses of patients in different CDR stages reveals that the total BPMSE-Ch score and subcomponent scores differ significantly between patients in CDR stage 2 versus those in CDR stage 3, and patients in both of these more severely impaired CDR stages exhibited a wide range of scores, with substantial variability. These results lend further support to the use of the BPMSE-Ch with severely impaired patients.
In conclusion, the BPMSE-Ch is a convenient, stable, reliable and valid scale to assess cognition in patients with moderate-severe AD, and is most appropriately used with patients who have MMSE scores 11 or below. And in future work, we should popularize the BPMSE-Ch in other areas of China including rural areas to research the properties about BPMSE. We believe that it would be beneficial for this instrument to be widely used for evaluating cognitive functioning of patients with severe AD in China.
Acknowledgments: Funding Information: This study was supported by grants from National Key R&D Program of China (2018YFC2001700), General Project of Technological Innovation and Application Development of Chongqing Science & Technology Bureau (cstc2019jscx-msxmX0239), Key project of Social undertakings and people’s livelihood security of Chongqing Science & Technology Commission (cstc2017shms-zdyfX0009) and Postgraduate Research Innovation Project of Chongqing(CYS16122), Particularly, we greatly thank Dr. Sergio Salmerón (Department of Geriatrics, Hospital General de Villarrobledo, Albacete, Spain) for the assistance in making a translation of BPMSE.
Conflict of Interest: The authors declare that they have no potential competing interests
Ethics approval and consent to participate: The study was approved by the Ethics Committee of The First Affiliated Hospital of Chongqing Medical University and has been performed in accordance with the ethical standards laid down in the Declaration of Helsinki and its later amendments.
Authors’ Contributions: Rachelle S. Doody and Yang Lü designed the study. Xue Fu, Weihua Yu and Yang Lü collected the data and wrote the paper. Yang Lü, Paul J. Massman and Rachelle S. Doody revised the manuscript: Xia Wang, Jia Zhang and Tao Luo analyzed data and assisted with writing the article.
1. J.C. Morris, K. Blennow, L. Froelich, et al. Harmonized diagnostic criteria for Alzheimer’s disease: recommendations, Journal of internal medicine2014; 275(3): 204-13.
2. F. Li, S. Chen, C. Wei, J. Jia. Monetary costs of Alzheimer’s disease in China: protocol for a cluster-randomised observational study, BMC neurology 2017; 17(1):15.
3. J. Jia, A. Zhou, C. Wei, et al. The prevalence of mild cognitive impairment and its etiological subtypes in elderly Chinese, Alzheimer’s & dementia : the journal of the Alzheimer’s Association 2014; 10(4): 439-47.
4. Y. Zhang, Y. Xu, H. Nie, et al. Prevalence of dementia and major dementia subtypes in the Chinese populations: a meta-analysis of dementia prevalence surveys, 1980-2010, Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia 2012;19(10): 1333-7.
5. K.Y. Chan, W. Wang, J.J. Wu, et al. Epidemiology of Alzheimer’s disease and other forms of dementia in China, 1990-2010: a systematic review and analysis, Lancet (London, England) 2013; 381(9882): 2016-23.
6. J. Jia, F. Wang, C. Wei, et al. The prevalence of dementia in urban and rural areas of China, Alzheimer’s & dementia : the journal of the Alzheimer’s Association 2014, 10(1): 1-9.
7. D. Liu, G. Cheng, L. An, et al. Public Knowledge about Dementia in China: A National WeChat-Based Survey, International journal of environmental research and public health2019; 16(21).
8. X. Li, W. Fang, N. Su, Y. Liu, S. Xiao, Z. Xiao, Survey in Shanghai communities: the public awareness of and attitude towards dementia, Psychogeriatrics : the official journal of the Japanese Psychogeriatric Society2011; 11(2): 83-9.
9. M. Zhao, X. Lv, M. Tuerxun, et al. Delayed help seeking behavior in dementia care: preliminary findings from the Clinical Pathway for Alzheimer’s Disease in China (CPAD) study, International psychogeriatrics 2016; 28(2): 211-9.
10. D. Peng, Z. Shi, J. Xu, et al. Demographic and clinical characteristics related to cognitive decline in Alzheimer disease in China: A multicenter survey from 2011 to 2014, Medicine2016; 95(26): e3727.
11. F.A. Schmitt, W. Ashford, C. Ernesto, et al. The severe impairment battery: concurrent validity and the assessment of longitudinal change in Alzheimer’s disease. The Alzheimer’s Disease Cooperative Study, Alzheimer disease and associated disorders1997; 11 Suppl 2: S51-6.
12. M.F. Folstein, S.E. Folstein, P.R. McHugh, «Mini-mental state». A practical method for grading the cognitive state of patients for the clinician, Journal of psychiatric research 1975; 12(3): 189-98.
13. J. Saxton, A.A. Swihart, Neuropsychological assessment of the severely impaired elderly patient, Clinics in geriatric medicine 1989; 5(3): 531-43.
14. S.J. Cano, H.B. Posner, M.L. Moline, et al. The ADAS-cog in Alzheimer’s disease clinical trials: psychometric evaluation of the sum and its parts, Journal of neurology, neurosurgery, and psychiatry2010; 81(12): 1363-8.
15. B. Reisberg, S.H. Ferris, M.J. de Leon, T. Crook. The Global Deterioration Scale for assessment of primary degenerative dementia, The American journal of psychiatry1982; 139(9): 1136-9.
16. B. Reisberg. Functional assessment staging (FAST), Psychopharmacology bulletin 1988; 24(4): 653-9.
17. C.P. Hughes, L. Berg, W.L. Danziger, L.A. Coben, R.L. Martin, A new clinical scale for the staging of dementia, The British journal of psychiatry : the journal of mental science 1982; 140: 566-72.
18. G.M. Peavy, D.P. Salmon, V.A. Rice, et al. Neuropsychological assessment of severely demeted elderly: the severe cognitive impairment profile, Archives of neurology 1996; 53(4): 367-72.
19. K.L. Lanctot, J. Amatniek, S. Ancoli-Israel, et al. Neuropsychiatric signs and symptoms of Alzheimer’s disease: New treatment paradigms, Alzheimer’s & dementia (New York, N. Y.)2017; 3(3): 440-449.
20. R.S. Doody, S.L. Strehlow, P.J. Massman, E.P. Feher, C. Clark, J.R. Roy, Baylor profound mental status examination: a brief staging measure for profoundly demented Alzheimer disease patients, Alzheimer disease and associated disorders 1999; 13(1): 53-9.
21. A. Korner, A. Brogaard, I. Wissum, U. Petersen, The Danish version of the Baylor Profound Mental State Examination, Nordic journal of psychiatry2012; 66(3): 198-202.
22. H.R. Na, S.H. Lee, J.S. Lee, R.S. Doody, S.Y. Kim, Korean version of the Baylor Profound Mental Status Examination: a brief staging measure for patients with severe Alzheimer’s disease, Dementia and geriatric cognitive disorders 2009; 27(1): 69-75.
23. S. Salmeron, I. Huedo, M. Lopez-Utiel, et al. Validation of the Spanish version of the Baylor Profound Mental Status Examination, Journal of Alzheimer’s disease 2016; 49(1): 73-8.
24. G. McKhann, D. Drachman, M. Folstein, R. Katzman, D. Price, E.M. Stadlan, Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease, Neurology1984; 34(7): 939-44.
25. R.H. Paul, R.A. Cohen, D.J. Moser, et al. The global deterioration scale: relationships to neuropsychological performance and activities of daily living in patients with vascular dementia, Journal of geriatric psychiatry and neurology 2002; 15(1): 50-4.
26. J.S. Kim, C.W. Won, B.S. Kim, H.R. Choi, Predictability of various serial subtractions on global deterioration scale according to education level, Korean journal of family medicine2013; 34(5): 327-33.
27. S.H. Choi, B.H. Lee, S. Kim, et al. Interchanging scores between clinical dementia rating scale and global deterioration scale, Alzheimer disease and associated disorders2003; 17(2): 98-105.
28. A.J. Midden, B.T. Mast, Differential item functioning analysis of items on the Geriatric Depression Scale-15 based on the presence or absence of cognitive impairment, Aging & mental health 2017; 1-7.