ORIGINAL RESEARCH Mild Dementia or Cognitive Impairment: The Modified Mini-Mental State Examination (3MS) as a Screen for Dementia Roger C Bland, MB, ChB, FRCPC1, Stephen C Newman, MSc, MD1 Objective: To examine the Modified Mini-Mental State Examination (3MS) as a screen for dementia. Method: A group of 1092 elderly Edmonton community residents completed the 3MS and the Geriatric Mental State Examination (GMS). 3MS sensitivity and specificity were determined by comparing positive 3MS screens (score ≤77) with those classified as GMS “organic” (severity level 3, equivalent to a clinical diagnosis). In the Canadian Study of Health and Aging (CSHA), 2914 subjects received the 3MS and a clinical examination. A group described as having “cognitive impairment but no dementia (CIND)” was identified. Results: In Edmonton, the 3MS showed 88% sensitivity, 90% specificity, 29% positive predictive value (PPV), and 99% negative predictive value (NPV). In the CSHA, 30% of subjects receiving both the 3MS and a clinical examination were classified as CIND. One-half of these were classified as having “age associated memory impairment (AAMI)” or as “unspecified.” Conclusions: The 3MS with a cutting score of 77/78 proved a reasonable screening instrument; 1 case in 3 screening “positive” has dementia, but few (0.64%) will be missed by screening “negative.” CIND, accounting for 2 out of 3 cases screened positive by the 3MS in the Edmonton study, is a substantial, heterogeneous group that is not necessarily “predementia” but that in many cases merits further investigation. (Can J Psychiatry 2001;46:506–510) Key Words: dementia screening, dementia epidemiology, Modified Mini-Mental State Examination (3MS), Geriatric Mental State Examination (GMS) ementias are primarily diseases affecting older age diagnosis of “organic” on the Geriatric Mental State Exami- D groups; they are likely to have the most impact in the es- tablished market economies, where life expectancy is the nation (GMS) (3–5) with a severity level of 3, equivalent to a clinical diagnosis. greatest, approaching 80 years. In Canada, assuming constant prevalence, actual cases are projected to increase more than Classifying Dementia 3-fold, from 253 000 in 1991 to 778 000 in 2031, an increase entirely due to demographic change (1). While little difficulty is experienced in detecting severe and advanced dementia cases, the problems of early detection re- To examine the Modified Mini-Mental State Examination main unresolved and arise at several levels (6–8). The (3MS) effectiveness (2) as a screening test for dementia, we DSM-III-R, ICD-10, and DSM-IV classification systems are used a community-based random sample of elderly subjects. not consistent. DSM-III-R describes 2 categories of mild cog- The gold standard for the diagnosis of dementia was a nitive impairment: type 1, short- and long-term memory im- pairment with no functional disability; and type 2, short-and longer-term memory impairment with no functional disabil- ity but with at least 1 of several other deficits. ICD-10 de- Manuscript received October 2000, revised, and accepted April 2001. 1Professor, Department of Psychiatry, University of Alberta, Edmonton, Al- scribes 3 categories, also called mild cognitive impairment: berta. type 1, short- or longer-term memory impairment with no Address for correspondence: Dr RC Bland, Department of Psychiatry, functional disability; type 2, short- or long-term memory im- 1E7.07 Mackenzie Centre, 8440B112 Street, Edmonton, AB T6G 2B7 e-mail: Roger.Bland@ualberta.ca pairment and intellectual decline with no functional disabil- ity; and type 3, short-or long-term memory impairment with Can J Psychiatry, Vol 46, August 2001 506 August 2001 Mild Dementia or Cognitive Impairment 507 Table 1. Canadian study of health and aging subcategories of Cognitive Impairment But No Cognitive Impairment But No Dementia (CIND)a Dementia (CIND) n % During the course of the Canadian Age-associated memory impairment (AAMI) 215 24.9 Study on Health and Aging (CSHA), Cerebrovascular 84 9.8 2914 subjects received both the 3MS Depression 69 8.0 and a clinical examination (1). Of this group, 30% were identified as having General vascular 65 7.5 CIND and were further examined to Psychiatric or delirium 57 6.6 determine the cause of cognitive im- Alcohol or drug abuse 72 8.3 pairment (17) (Table 1). One-half of Other specified 85 9.9 this group were classified either as Unspecified 215 24.8 having AAMI or as “unspecified.” a CIND was determined as follows: de- Adapted from (17) mentia criteria were not met, a clini- cian identified a memory deficit, there intellectual decline and personality change but with no func- was a deficit in 1 other area of cogni- tional dis abil ity. DSM-IV in tro duces the terms “mild tion, the deficit did not seriously interfere with daily living, neurocognitive disorder,” which requires a neurological or and there was a clinical impression that “something was go- general medical etiology, and “age-related cognitive de- ing on.” cline,” a decline in functioning that is within normal limits for age and is not due to a general medical condition or other Methods mental disorder. Subjects The term “age-associated memory impairment” (AAMI) has Trained lay interviewers interviewed a stratified random established criteria specifying performance ≥1 SD below the sample of 1092 community residents age 65 years or over young adult mean on 1 or more tests. Other terms used in- from the city of Edmonton, Alberta, (population over clude “age-consistent memory impairment,” “late-life forget- 500 000). The sample was obtained using provincial health fulness,” and “age-associated cognitive decline” (9). The care registration data that include more than 99% of the popu- problems with these classifications and their criteria include lation. The response rate was 82.3% of the eligible subjects. complexity, reliance on tests without adequate norms, vague Stratification was by age to oversample the oldest groups. definitions of memory impairment, and inconsistent applica- Instruments tion in research—all leading to poor comparability of results. All subjects were administered the 3MS (2) and the GMS (3–5). Prognostic Significance The 3MS has demonstrated superiority to the more popular Mini-Mental State Examination (MMSE); it shows better va- If early cognitive decline is benign and those affected do not lidity in identifying dementia and all levels of cognitive im- proceed to dementia, this is clearly important. Conversely, if pair ment. The ar eas un der the re ceiver op er at ing early cognitive decline accurately detects early dementia, characteristic (ROC) curve were significantly greater at 0.94 those affected would be suitable subjects for early interven- for the 3MS, compared with 0.89 for the MMSE. The 3MS in- tions, when opportunities arise. In prospective studies, sev- corporates additional questions in 4 areas (personal informa- eral reports have shown that subjects identified with mild tion, verbal fluency, abstraction, and long-term recall) and cognitive impairment proceed in most cases to dementia after more important, uses an expanded scoring system. The cut- a 2- to 7-year follow-up (10 – 14). Nevertheless, even in those ting score used on the 3MS was 77/78. This was the cutting studies that show a high percentage of cases progressing from score determined in the CSHA to provide optimum sensitiv- mild cognitive impairment to dementia, at least one-third do ity (87%) and specificity (89%) for detecting dementia (18). not progress. Although a recent study found 18.5% of the population over age 50 years to have AAMI, it would seem The GMS is an instrument that has undergone progressive de- beyond the realm of possibility that such a high proportion of velopment over many years and has been widely used in both this population is in the stage of predementia, nor do the au- clinical and community studies. The version used (version thors suggest it (15). Förstl and others reported a prospective A3) was computer-administered by trained interviewers. The study showing that the distinction between AAMI and Alz- diagnosis is derived using the computerized diagnostic sys- heimer’s disease (AD) did not predict cognitive deterioration tem, AGECAT, not clinical judgment. Current symptoms are during a 2-year follow-up (16). collected into 8 syndrome clusters, 1 of which is the “organic” 508 The Canadian Journal of Psychiatry Vol 46, No 6 years and 3.5% in those age 75 to 84 years to 14.3% in those age 85 years and over. The prevalence of CIND for the comparable age groups was 3.8%, 10.4%, and 22.0%. Thus, it may be seen that the increase with age of both GMS organic and CIND is almost logarith- mic, but with a steeper slope for the GMS organic classification. At all ages, the prevalence of CIND is 2 to 3 times greater than the prevalence of GMS or- ganic (Figure 1). Figure 2 shows the statistics comparing the 3MS as a screening test with GMS organic as the gold standard. The sensi- tivity is 88%, specificity 90%, positive predictive value (PPV) 29%, and nega- tive predictive value (NPV) 99%; the chance of having the illness (dementia) Figure 1. GMS Organic and CIND by age, age-specific prevalences, both sexes (n = 1092). if the 3MS test is negative is 0.64%. Discussion cluster. This cluster includes the dementias but does not dif- ferentiate the various etiologies. Each cluster is assigned a At 2.9%, the prevalence of dementia (GMS organic) in this “level of confidence,” a measure of diagnostic certainty on a study is slightly lower than the prevalence found in the CSHA scale of 0 to 5, where 3 is the level of clinical significance that community sample from the Prairies, which was 3.7% (4.8% would ordinarily require intervention. A second level of anal- for men, 2.9% for women). This CSHA sample included sub- ysis with the AGECAT introduces hierarchies of diagnosis, jects from 4 centres, not just Edmonton. Neither the preva- but this was not used in our study. lence found using the GMS in this study (2.9%) nor that found in the CSHA represents the population prevalence, because Diagnoses institutionalized people were not part of these samples. The diagnosis of dementia was based on a GMS–AGECAT classification of organic at a severity level of 3, the level that It is obvious that a considerable number of the elderly show is considered to be the equivalent of a clinical diagnosis. For cognitive impairment but fail to meet criteria for dementia. this study, the diagnosis of CIND was defined as scoring 77 or Follow-up studies have demonstrated that a proportion of less on the 3MS and not being classified as GMS organic. these subjects will likely develop dementia. In all studies, Note that this is somewhat simpler than the definition used in however, a considerable number do not seem to progress to the CSHA, wherein there was direct clinical examination. dementia. The designation of CIND for those who show cog- nitive impairment without any additional evidence of demen- Analyses tia seems a useful concept: it may indicate the need for further The prevalence of GMS organic disorders and of CIND as de- clinical investigation, and certainly, in some cases, it predicts fined above was calculated for each elderly age group. The future dementia. test characteristics of the 3MS compared with the GMS were It should be noted that the term CIND was also used in the also calculated. CSHA. Although the concept is similar in both studies, the operational definitions (as given above) differ. Direct com- Results parisons of prevalences of CIND between the studies must The response rate from the eligible subjects was 82.3%; therefore be made cautiously. 59.6% were women, 40.4% were men, and 53.0% of the re- spondents were married. Further descriptions of the methods Like many other studies, the Edmonton study clearly demon- are available in earlier communications (19,20). strated that the prevalence of dementia increases almost ex- ponentially with age, but so does CIND. The prevalence of The overall weighted prevalence of GMS organic in the pop- CIND is at all ages greater than that of dementia by a factor of ulation age 65 years and older was 2.9% (men 2.5%, women 2 or 3. As did the CSHA, the Edmonton study illustrated that 3.2%); this varied from a low of 1.4% in those age 65 to 74 the 3MS (using the cutting score of 77/78) is a reasonable August 2001 Mild Dementia or Cognitive Impairment 509 Clinical Implications • The Modified Mini-Mental State Examination (3MS) is a highly sensitive instrument for the detection of dementia. • The 3MS detects cases with cognitive impairment but no dementia (CIND) that warrant further investigation. • The 3MS is easily used as a screening instrument. Limitations • The 3MS does not differentiate the causes of dementia. • Only one-third of those screening positive for cognitive impairment on the 3MS will actually have dementia. • The 3MS takes slightly longer to administer than the Mini-Mental State Examination (MMSE). • memory complaints should be evaluated and patients fol- lowed up to assess progression • when caregivers or informants describe cognitive decline, these observations should be taken seriously, with cogni- tive assessment indicated. These comments are largely based on experience using the MMSE in general populations of 65- to 74-year-old people. The consensus group stated that the MMSE has an average sensitivity of 83% and an average specificity of 82%, with a false-positive rate of 93%. Obviously, these results are less Figure 2. Edmonton Community Study 3MS ≤ 77 as the screening satisfactory than those which we obtained using the 3MS. test, GMS “organic” as the gold standard. Nevertheless, we found a false-positive rate of 71%, and this could create unnecessary anxiety if random population screening instrument for detecting cognitive impairment and screening were to be undertaken, not to mention possibly ex- dementia. That this instrument is readily available, takes only pensive and time-consuming unnecessary further investiga- a few minutes to administer, and can be administered by tion. Against this must be weighed the very low proportion of trained nonclinicians all indicate that it is satisfactory for false negatives (0.64%) and the consideration that must be screening general elderly populations. It can easily be admin- given to causes of cognitive impairment other than dementia; istered in general practice settings, in public health clinics, or these may need investigation. It should be noted that the Con- in clinics for the elderly. A screening instrument for the popu- sensus Conference group questioned the usefulness of identi- lation should be sensitive in the detection of the mild or early fying CIND, seemingly on the basis that its natural history is cases that may be found outside clinical settings; it should be unclear. The group states, however, that annually 5% to 6% of noted that the Edmonton study used a random sample of com- CIND survivors progress to dementia. Moreover, Ebly, Ho- munity-resident elderly and not a clinical sample, which gan, and Parhad have clearly shown that about one-half of would have introduced a bias toward more severe cases. CIND cases are due to causes that require further investiga- tion and treatment (17). Thus, we argue that it is both practical The results of the Canadian Consensus Conference on De- and useful to detect cases of CIND. We also recommend that mentia were published in 1999 (21) and, with reference to in routine clinical practice there are good reasons to replace screening and case finding for dementia, concluded that the original MMSE with the 3MS. • there was insufficient evidence to recommend for or We demonstrated that the 3MS has a high sensitivity in de- against screening in the absence of symptoms tecting dementia cases in the elderly population, with only a • there was insufficient evidence for or against screening 0.64% chance of the illness being present if the test is nega- with short mental status questionnaires in unselected older tive. Of those screening positive on the 3MS, however, only 1 people in 3 in the general elderly population will actually have an ill- • given the burden of dementia for older people and their ness classifiable as a dementia (the false-positive rate was caregivers, family physicians should have a high index of 71%). This considerably narrows the field of those who may suspicion for dementia and follow up concerns regarding need to be investigated further. Particular attention should be functional decline and memory loss paid to possible vascular causes, to psychiatric illness 510 The Canadian Journal of Psychiatry Vol 46, No 6 9. Blackford RC, LaRue A. Criteria for diagnosing age-associated memory impair- including depression or delirium, and to substance use in ment: proposed improvements from the field. Developmental Neurosychology those classified as CIND; that is, those falling below the 1989;5:295–306. cut-off on the 3MS but failing to meet criteria for a diagnosis 10. Katzman R, Aronson M, Fuld P, Kawas C, Brown T, Morgenstern H, and others. Development of dementing illnesses in an 80-year old volunteer cohort. Ann of GMS organic. Neurol 1989;25:317–24. 11. Rubin EH, Morris JC, Grant EA, Vendegna T. Very mild senile dementia of the Acknowledgment Alzheimer type. Arch Neurol 1989;46:379–82. 12. Flicker C, Ferris SH, Reisberg B. Mild cognitive impairment in the elderly. Neurol- This study was funded in part by the National Health Research De- ogy 1991;41:1006–9. velopment Program. 13. Peterson RC, Smith GE, Tangalos EG, Kokmen E, Ivnik J. Longitudinal outcome of patients with a mild cognitive impairment. Ann Neurology 1993;34:294–5. 14. O’Connor DW, Pollitt PA, Jones BJ, Hyde JB, Fellowes JL, Miller ND. Continued References clinical validation of dementia diagnosed in the community using the Cambridge mental disorders of the elderly examination. Acta Psychiatr Scand 1991;83:41–5. 1. CSHA Working Group. Canadian study of health and aging. Study methods and 15. Barker A, Jones R, Jennison C. A prevalence study of age associated memory im- prevalence of dementia. Can Med Assoc J 1994;150:899–913. pairment. Br J Psychiatry 1995;167:642–8. 2. Teng EL, Chui HC. The modified mini mental state (3MS) examination. J Clin Psy- 16. 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Community screening for demen- nostic system and case nomenclature for elderly subjects: GMS and AGECAT. tia: The mini mental state exam (MMS) and modified mini mental state exam Psychol Med 1986;6:89–99. (3MS) compared. J. Clin Epidemiol 1997;50:377–83. 5. Copeland JR, Dewey ME, Wood N, Searle R, Davidson IA, McWilliam C. Range 19. Newman SC, Sheldon CT, Bland RC. Prevalence of depression in an elderly com- of mental illness among the elderly in the community: prevalence in Liverpool us- munity sample: a comparison of GMS-AGECAT and DSM-IV diagnostic criteria. ing the GMS-AGECAT package. Br J Psychiatry 1987;150:815–23. Psychol Med 1998;8:1339– 4 5. 6. Henderson AS, Huppert FA. The problem of mild dementia. Psychol Med 20. Newman SC, Bland RC, Orn HT. The prevalence of mental disorders in the elderly 1984;14:5–11. in Edmonton: a community survey using the GMS-AGECAT. Can J Psychiatry 7. Kay DWK, Henderson AS, Scott R, Wilson J, Rickwood D, Grayson DA. Dementia 1998;43:910– 4 . and depression among the elderly living in the Hobart community: the effect of the 21. Patterson CJS, Gauthier S, Bergman H, Cohen CA, Feighner JW, Feldman H, and diagnostic criteria on the prevalence rates. Psychol Med 1985;15:771–88. others. The recognition, assessment and management of dementing disorders: con- 8. Mowry BJ, Burvill PW. A study of mild dementia in the community using a wide clusions from the Canadian consensus conference on dementia. Can Med Assoc J range of diagnostic criteria. Br J Psychiatry 1988;153:328–34. 1999;160 (Suppl 12): 1S–15S. Résumé — Démence légère ou déficit cognitif : le mini-examen modifié de l’état mental (3MS) pour le dépistage de la démence Objectif : Étudier le mini-examen modifié de l’état mental (3MS) comme instrument de dépistage de la démence. Méthode : Un groupe de 1 092 personnes âgées de la région d’Edmonton ont répondu au 3MS et à l’examen de l’état mental gériatrique (GMS). La sensibilité et la spécificité du 3MS ont été déterminées en comparant les scores positifs du 3MS (score 77) avec ceux classés comme étant « organiques » du GMS (niveau de gravité 3, l’équivalent d’un diag- nostic clinique). Dans l’Étude sur la santé et le vieillissement au Canada (ESVC), 2 914 sujets ont répondu au 3MS et subi un examen clinique. On y a distingué un groupe décrit comme ayant « un déficit cognitif mais sans démence (DCSD) ». Résultats : À Edmonton, le 3MS a démontré une sensibilité de 88 %, une spécificité de 90 %, une valeur prédictive posi- tive (VPP) de 29 % et une valeur prédictive négative (VPN) de 99 %. Dans l’ESVC, 30 % des sujets ayant répondu au 3MS et subi un examen clinique ont été classés DCSD. La moitié de ces derniers ont été classés comme ayant un trouble de la mémoire lié à l’âge (TMLA) ou « non spécifié ». Conclusions : Avec une note tronquée de 77/78, le 3MS s’est révélé un instrument de dépistage raisonnable. Un cas sur 3 ayant une note « positive » souffre de démence, mais quelques-uns (0,64 %) ne sont pas détectés à cause d’un DCSD « négatif », ce qui représente 2 cas sur 3 qui ont eu un dépistage positif par le 3MS dans l’étude d’Edmonton. Il s’agis- sait d’un groupe important et hétérogène qui n’est pas nécessairement au stade de la « pré-démence » mais qui, dans bien des cas, mérite un examen approfondi.
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