Mild Dementia or Cognitive Impairment The Modified Mini Mental by mikeholy

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									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
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      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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