Screening for Cognitive Impairment in the Elderly pot

Screening
for Cognitive
Impairment
in the Elderly
CHAPTER
75
By Christopher Patterson
Screening for Cognitive Impairment
75
in the Elderly
Prepared by Christopher Patterson, MD, FRCPC
1
C
ognitive impairment is a common finding in older people,
as the prevalence of dementia increases with age. The most
common cause of dementia is Alzheimer’s disease, a slowly
progressive primary dementing disorder. Intercurrent illnesses,
infections, metabolic disturbances and drug intoxications may all
cause or exacerbate mental confusion. Depression may worsen
and occasionally mimic dementia. Identification of dementia in
the early stages offers the potential to plan to deal with
subsequent deterioration, organize community supports, and
anticipate later incompetence, by measures such as advance
directives and power of attorney. A large number of drugs have
been studied for their effect on improving the cognitive and
behavioural aspects of Alzheimer’s disease. While beneficial
effects on cognitive performance have been documented, these
are rarely of sufficient magnitude to be of clinical importance.
The potential harm of labelling an individual as demented must
be weighed against possible benefits. There is insufficient
evidence to recommend for or against measures to detect

asymptomatic cognitive impairment. The prudent physician is
advised to remain alert for clues that suggest deteriorating
cognitive function, and then to pursue an appropriate diagnostic
course of action.
Burden of Suffering
Prevalence studies in Europe, the United States and Canada
reveal relatively consistent findings. While methods of ascertainment
Prevalence of
dementia is less than
5% below 75 years of
age, but above 40%
over age 80 years
vary from study to study, the prevalence of severe dementia in people
aged 65 and over residing in the community is between 2.5 and
5%.<
1
-3> For mild degrees of dementia the prevalence is age-
dependent, with rates less than 5% below 75 years, to 40% or higher
above the age of 80.<4> The incidence has been estimated at
1
% in
persons over 65 and up to 2.5% in those over the age of 80. Projected
figures for Canada are 225,000 new cases of dementia per year.<3> In
addition to the cognitive deficits produced by dementia, behavioural
abnormalities are common. These frequently lead to excessive
caregiver stress, and may precipitate hospital or institutional admission.
Behaviours such as restlessness, wandering, aggression, failure to
1
Professor and Head, Division of Geriatric Medicine, McMaster University,
Hamilton, Ontario

902
recognize relatives and locations, and inappropriate sexual behaviour
are particularly troublesome. The presentation of physical disease may
be altered or obscured. People with dementia have reduced survival.
Maneuver
Dementia is readily recognizable in its advanced stages. In the
early stages it often goes undetected. Conventional medical histories
and examinations frequently fail to identify cognitive impairment or
to distinguish it from hearing impairment, depression, aphasia,
bradykinesia, etc. Criteria have been established for the diagnosis of
dementia.<5,6> While the “complete mental state” examination is well
described in standard texts, attempts have been made to develop short
mental status questionnaires to screen for cognitive impairment. The
Mini Mental State examination (MMS)<7> is the most frequently used
and has the most clearly defined test characteristics. Others include
the Short Portable Mental Status Questionnaire (SPMSQ)<8> and the
Clock Drawing test.<9> The MMS requires no special equipment and
can be completed within 5-
1
0 minutes. Little training is required, and a
standardized version has been developed.<
1
0> The sensitivity of this
instrument to detect moderate dementia approaches 90% with a cut-
off point of 24 out of 30. Corresponding specificity is about 80%.
The test is valid and reproducible, particularly in its standardized
form.<
1
0> The SPMSQ has had similar sensitivity in published
series,<

11
> but has been less well studied. It is a less comprehensive
instrument than the MMS, as it examines principally orientation and
memory, and does not cover areas of language or motor tasks. The
clock drawing test, originally developed for examination of parietal
lobe function, is an extremely quick test. Despite its simplicity, it offers
excellent sensitivity (92%) and specificity (97%) for the detection of
moderate to severe dementia.<
1
2>
An alternative approach to the use of mental status
questionnaires is screening using Instrumental Activities of Daily Living
(IADL). Sixty-nine percent of a random sample of 2,792 community
dwellers aged 65 years and over were subjected to a two-phase
screening procedure. The first phase included a functional assessment
using an IADL scale and the MMS. Subjects who fulfilled Diagnostic and
Statistical Manual of Mental Disorders criteria for dementia, were
evaluated by a neurologist using National Institute of Neurological
Diseases and Stroke – Alzheimer Disease and Related Disease
Association criteria for dementia. The prevalence of dementia in this
sample was 2.4%. Subjects experiencing difficulty in telephone use, use
of public transportation, responsibility for medication use and handling
finances had a
1
2 times greater probability of being diagnosed with
dementia.<
1
3> The MMS score is correlated with the ability to
perform daily activities in cognitively impaired individuals.<
1

4>
903
When an older person is discovered to have cognitive
impairment a search is usually made for illnesses causing cognitive
impairment which may be modifiable, in the hope that the condition
will be improved or reversed. Although earlier literature suggested
that up to one third of cases of apparent dementia were caused by
illnesses whose treatment could lead to improvement, a recent
overview analysis of the subject concluded that only
11
% of dementing
illnesses in older people resolved during follow-up (8% partially,
3% completely). The most common underlying remediable factors
were drug intoxication, depression and metabolic abnormalities.<
1
5>
Two recent large community studies have been carried out to examine
the results of screening and subsequent investigations. In a three-phase
study in Eastern Baltimore, Md, 78% of 3,48
1
subjects completed the
National Institute of Mental Health Interview Survey questionnaire
together with a version of the MMS. Eighty percent of a random
sample of these subjects (n=
1
,806) were examined by psychiatrists.
Thirty-six of the 44 diagnosed by a psychiatrist as having definite or
probable dementia were subjected to full neurological investigations.
The prevalence of dementia was 6.
1

% in this population and no cases
of reversible dementia were found.<
1
6> In a second large community
study from East Boston, 3,624 subjects over the age of 65 were
examined with a screening procedure based on detection of immediate
and delayed memory. Four hundred and seventy-two who appeared to
have cognitive impairment were identified. Of these, 83.5% were found
to have a clinical diagnosis of probable Alzheimer’s disease.<4> The
vast majority of older community subjects discovered by screening to
have cognitive impairment are suffering from Alzheimer’s disease and
do not have a correctable or even potentially correctable dementing
illness. While there are theoretical reasons to identify people with
dementia for early treatment, early intervention has not been shown
to modify the course of the illness. Theoretically, in those who have
vascular dementia, correction of risk factors (e.g. treatment of
hypertension, or anticoagulation for atrial fibrillation) could delay the
progress of dementia. A wide variety of agents have been tested in
Alzheimer’s disease. Drugs presently showing most promise increase
the central levels of acetyl choline. Tacrine (tetrahydroaminoacridine),
has been approved for use in the United States and is available in
Canada. Modest but definite improvements in cognitive performance
have been documented in some<
1
7-
1
9> but not all<20,2
1
> studies.
Drugs which promote enhanced cerebral metabolism have also shown

some benefit, although drugs such as Hydergine have largely been
abandoned in the face of recent studies which have shown no
significant effect.<22> Chelation therapy with desferrioxamine has
shown some promise and may delay disability in Alzheimer’s
disease.<23> There are no published trials examining the effects of
treatment on subjects who have been discovered by community
screening to suffer from cognitive impairment.
904
One potential benefit of early identification is the ability to plan
for the anticipated further cognitive decline. For example, the
assignment of a sustaining power of attorney can be made at a time
before mental incompetence occurs, obviating more complex
maneuvers to handle an individual’s estate at a later date. The ability to
discuss advance directives with an individual is another potential
benefit. Planning and consideration of timely relocation to a more
protected environment may also be beneficial and early involvement
with caregiver support groups may assist individuals in dealing with
ultimate disability. None of these theoretical advantages has been
subjected to appropriate study.
Potential negative consequences of early identification of
cognitive impairment clearly exist. Labelling an individual as demented
A label of dementia
provokes negative
attitudes among
professionals and lay
people
may affect his or her ability to obtain life or health insurance, and may
influence attitudes towards the individual by health care professionals
and others. The label of Alzheimer’s disease may cause prejudice and
difficulty in gaining admission to some long-term facilities. The negative

effects of labelling an older person as demented have not been studied
systematically, although a small body of social science literature
explores this important area.<24> Negative attitudes have been
identified among professionals and lay people.
Recommendations of Others
The U.S. Preventive Services Task Force recommended against
screening for cognitive impairment in
1
989.<25>
Conclusions and Recommendations
Despite the theoretical advantages of identifying individuals with
cognitive impairment, there is no evidence to indicate whether this
Caregivers should be
alert for reports or
signs of behaviour
that signal the need
to investigate for
dementia
leads to a net benefit or risk to the individual. Although pharmaceutical
agents are able to produce measurable changes in cognitive
performance in people with Alzheimer’s disease, none has been shown
to result consistently in clinically significant improvement. The high
cost of investigation to exclude reversible causes of dementia, and the
negative effects of labelling are examples of potential harm.
Identification of asymptomatic cognitively impaired individuals by the
use of short mental status tests or by any other means has not been
demonstrated to produce benefit. Thus there is insufficient evidence
to recommend for or against screening (C Recommendation). The
prudent physician should be alert for any reports or behaviour which
may indicate cognitive impairment (e.g. forgetting appointments, poor

medication compliance), and then pursue appropriate strategies for
further investigation and treatment.<26>
905
Unanswered Questions (Research Agenda)
1
. Although two of the brief mental status instruments reviewed
appear satisfactory for case finding in primary care, they are not
ideal, and more sensitive and specific instruments are desirable.
2. The search for effective treatments for Alzheimer’s disease
should incorporate outcome measures including physical
functioning, behaviour measures of caregiver burden and ability
to delay or prevent institutional care.
3. Trials of screening are necessary to examine the impact of
detecting cognitive impairment, its subsequent investigation and
treatment.
4. Studies should be directed towards discovering any negative
effects from attaching the label of Alzheimer’s disease or
cognitive impairment to a person.
Evidence
Subsequent to the background paper prepared in
1
988, search of
the recent literature (
1
988-Dec
1
993) was carried out using the
following terms: mass screening (MH), geriatric assessment (MH),
cognition disorders (MH). This review was initiated in October
1

993 and updates a report published in
1
99
1
.<27> Recommendations
were finalized by the Task Force in January
1
994.
Selected References
1
. Broe GA, Akhtar AJ, Andrews GR,
et al
: Neurological disorders
in the elderly at home.
J Neurol Neurosurg Psychiatry
1976;
39: 361-366
2. Weissman MM, Myers JK, Tischler GL,
et al
: Psychiatric
disorders (DSM-III) and cognitive impairment in the elderly in a
U.S. urban community.
Acta Psychiatr Scand
1985; 71: 366-379
3. Canadian Study for Health and Aging (CSHA) Unpublished
results. Ottawa, 1992
4. Evans DA, Funkenstein HH, Albert MS,
et al
: Prevalence of
Alzheimer’s disease in a community population of older

persons.
JAMA
1989; 262: 2551-2556
5. American Psychiatric Association:
Diagnostic and statistical
manual of mental disorders
. (3rd Edition) (DSM-III),
Washington, D.C. 1980
6. McKhann G, Drachman D, Folstein M,
et al
: 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.
Neurology
1984;
34: 939-944
906
7. Folstein MF, Folstein SE, McHugh PR: “Mini-Mental-State”: A
practical method for grading the cognitive state of patients for
the clinician.
J Psychiatr Res
1975; 12: 189-198
8. Pfeiffer E: A short portable mental status questionnaire for the
assessment of organic brain deficits in the elderly.
J Am Geriatr
Soc
1975; 23: 433-441
9. Shulman K, Shedletsky R, Silver IL: The challenge of time:
clock drawing and cognitive functioning in the elderly.

Int J
Geriatr Psychiatry
1986; 1: 135-140
1
0. Molloy DW, Alemayehu E, Roberts R: Reliability of a
Standardized Mini-Mental State Examination compared with the
traditional Mini-Mental State Examination.
Am J Psychiatry
1991; 148: 102-105
11
. Erkinjuntti T, Sulkava R, Wikstrom J,
et al
: Short portable
mental status questionnaire as a screening test for dementia
and delirium among the elderly.
J Amer Geriatr Soc
1987;
35: 412-416
1
2. Tuokko H, Hadjistavropoulos T, Miller JA,
et al
: The Clock Test:
a sensitive measure to differentiate normal elderly from those
with Alzheimer Disease.
J Am Geriatr Soc
1992; 40: 579-584
1
3. Barberger-Gateau P, Commenges D, Gagnon M,
et al
:

Instrumental activities of daily living as a screening tool for
cognitive impairment and dementia in elderly community
dwellers.
J Am Geriatr Soc
1992; 40: 1129-1134
1
4. Warren EJ, Grek A, Conn D,
et al
: A correlation between
cognitive performance and daily functioning in elderly people.
J Geriatr Psychiatry Neurol
1989; 2: 96-100
1
5. Clarfield AM: The reversible dementias, do they reverse?
Ann Intern Med
1988; 109: 476-486
1
6. Folstein MF, Anthony JC, Parhad I,
et al
: The meaning of
cognitive impairment in the elderly.
J Am Geriatr Soc
1985;
33: 228-235
1
7. Summers WK, Majovski LV, Marsh GM,
et al
: Oral
tetrahydroaminoacridine in long-term treatment of senile
dementia, Alzheimer type.

N Eng J Med
1986; 315: 1241-1245
1
8. Davis KL, Thal LJ, Gamzu ER,
et al
: A double-blind placebo-
controlled multicentre study of tacrine for Alzheimer’s disease:
The Tacrine Collaborative Study Group.
N Eng J Med
1992;
327: 1253-1259
1
9. Farlow M, Gracon SI, Hershey LA,
et al
: A controlled trial of
tacrine in Alzheimer’s disease.
JAMA
1992; 268: 2523-2529
20. Gauthier S, Bouchar R, Lamontagne A,
et al
:
Tetrahydroaminoacridine – Lethicin combination treatment in
patients with intermediate stage Alzheimer’s disease: results
of a Canadian double-blind crossover, multicentre study.
N Eng J Med
1990; 322: 1272-1276
2
1
. Molloy DW, Guyatt GH, Wilson DB,
et al

: Effect of
tetrahydroaminoacridine on cognition, function and behaviour in
Alzheimer’s disease.
Can Med Assoc J
1991; 144: 29-34
907
22. Thompson TL, Filley CM, Mitchell WD,
et al
: Lack of efficacy of
hydergine in patients with Alzheimer’s disease.
N Eng J Med
1990; 323: 445-448
23. Crapper McLaughlan DR, Dalton AJ, Kruck TP,
et al
:
Intramuscular desferrioxamine in patients with Alzheimer’s
disease.
Lancet
1991; 337: 1304-1308
24. Lasoski MC, Thelen MH: Attitudes of older and middle-aged
persons towards mental health intervention.
Gerontologist
1987;
27: 288-292
25. U.S. Preventive Services Task Force:
Guide to Clinical
Preventive Services: an Assessment of the Effectiveness of
169 Interventions
. Williams & Wilkins, Baltimore, Md, 1989:
251-255

26. Clarfield AM, Bass MJ, Cohen C,
et al
: Assessing dementia:
The Canadian Consensus.
Can Med Assoc J
1991; 144:
851-853
27. Canadian Task Force on the Periodic Health Examination: The
periodic health examination, 1991 update: 1. Screening for
cognitive impairment in the elderly.
Can Med Assoc J
1991;
144: 425-431
908
Screening with short
mental status
instruments
The Mini Mental State
examination (MMS),
Short Portable Mental
Status Questionnaire
(SPMSQ) and clock-
drawing test have high
sensitivity and
specificity for
detection of cognitive
impairment but early
intervention has not
been shown to modify
the course of illness.

Potential harm of
labelling individuals as
demented has not
been systematically
studied but must be
weighed against
possible benefits.
Cohort analytic
studies<4,16> (II-2);
case series
<10-12> (III)
Expert opinion<24>
(III)
Insufficient evidence
to recommend for or
against screening (C);
the prudent physician
should be alert for any
symptoms which
suggest cognitive
impairment and
conduct appropriate
assessment
M
ANEUVER
E
FFECTIVENESS
L
EVEL OF
E

VIDENCE
<
REF
>
R
ECOMMENDATION
S UMMARY TABLE CHAPTER 75
Screening for Cognitive Impairment in the Elderly
909