Correspondence

A Population-Based Study of Dementia in 85-Year-Olds

N Engl J Med 1993; 329:63-64July 1, 1993

Article

To the Editor:

Skoog et al. and Larson (Jan. 21 issue)1,2 emphasize that a lack of diagnostic criteria is one of the major reasons for the paucity of epidemiologic studies of vascular dementia. To address this problem, the National Institute of Neurological Disorders and Stroke (NINDS) and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (AIREN) in Geneva organized an international workshop to propose diagnostic criteria for vascular dementia3.

The resulting NINDS-AIREN diagnostic criteria for research studies of vascular dementia4 emphasize the heterogeneity of the cerebrovascular disorders underlying vascular dementia, including ischemic and hemorrhagic strokes, cerebral hypoxic-ischemic events, and senile leukoencephalopathy. According to NINDS and AIREN, the diagnosis of vascular dementia requires the following: first, the patient must have dementia, according to the definition of the World Health Organization,5 preferably with neuropsychological documentation; second, there must be evidence of cerebrovascular disease demonstrated by the history, the clinical examination (with a finding of focal neurologic deficits), or brain imaging; and third, the two disorders must be reasonably related. The most reliable correlation appears to be temporal association, with an arbitrary time limit of three months for the onset of dementia after stroke.

The use of the criterion of temporal association should prevent the misclassification of patients with progressive dementia and stroke as having vascular dementia, or their inclusion in the ill-defined group of patients with mixed dementia, which can result from the use of the ischemic score, as demonstrated by Skoog et al1. The NINDS-AIREN criteria stratify cases according to the degree of certainty as definite, probable, and possible cases. The criteria also emphasize that clinical findings such as gait disorder, incontinence, or mood or personality disorder early in the course of dementia support a diagnosis of vascular dementia.

An understanding of the pathogenesis of vascular dementia is required for optimal prevention and treatment. The criteria used by Skoog et al.1 are quite close to the NINDS-AIREN criteria. Their study not only showed that in the very eldery vascular dementia may be the most common form of dementia but also demonstrated the feasibility of including imaging studies and neuropsychological evaluations in population-based studies of dementia.

Gustavo C. Roman, M.D.
Murray Goldstein, D.O., M.P.H.
National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892

5 References

1. 1

   Skoog I, Nilsson L, Palmertz B, Andreasson L-A, Svanborg A. A population-based study of dementia in 85-year-olds. N Engl J Med 1993;328:153-158
   Full Text | Web of Science | Medline

2. 2

   Larson EB. Illnesses causing dementia in the very elderly. N Engl J Med 1993;328:203-205
   Full Text | Web of Science | Medline

3. 3

   Roman GC, ed. Vascular dementia: proceedings of the NINDS-AIREN Workshop on Vascular Dementia, Bethesda, Md., April 19-21, 1991. New Issues Neurosci 1992;4:79-183
   

4. 4

   Roman GC, Tatemichi TK, Erkinjuntti T, et al. Vascular dementia: diagnostic criteria for research studies: report of the NINDS-AIREN International Workshop. Neurology 1993;43:250-260
   Web of Science | Medline

5. 5

   World Health Organization. The neurological adaptation of the international classification of diseases (ICD-10NA). Geneva: World Health Organization, 1991.
   

To the Editor:

Skoog et al. reported that the prevalence of dementia was 30 percent in a sample of 85-year-olds. This high prevalence of dementia raises several issues. Both people living in the community and those in institutions were invited to participate in their study. We suspect that healthy subjects living at home, who were not dependent on nurses and physicians, declined to participate more often than subjects living in institutions. Since the rate of dementia is higher among subjects living in institutions than among those living at home, this difference in the rates of participation could introduce a bias leading to the observation of a high rate of dementia overall. Among the 229 subjects who declined to participate in the investigation, it would be interesting to know the percentages living at home and living in institutions.

In an attempt to unravel the problems of depression and dementia, recommendations have been made to use depression scales specific to the elderly1. No reference was made by Skoog et al. to the use of antidepressants. Thus, it is not surprising that Skoog et al. reported only three patients with depression (2 percent). This figure is quite low as compared with the prevalence of depression among the elderly, which ranges from 2 percent to 20 percent2. Skoog et al. probably underestimated the rate of depression and overestimated the rate of dementia.

Skoog et al. recorded current use of drugs, but they did not report the results. It would be interesting to know the rate of prescription of benzodiazepines and drugs with anticholinergic properties. Some patients taking benzodiazepines might have been diagnosed as having mild dementia because of the amnestic properties of the drugs. Ten of the 25 most commonly prescribed drugs for the elderly have anticholinergic properties3. Some patients receiving such drugs could have impairments in memory misdiagnosed as dementia.

Jean-Claude Monfort, M.D.
Hopital Albert Chenevier, 94010 Creteil, France

3 References

1. 1

   Kalayam B, Shamoian CA. Evolution of research in geriatric psychiatry. Int J Geriatr Psychiatry 1993;8:3-12
   CrossRef | Web of Science

2. 2

   Hasegawa K. The epidemiological study of depression in late life. J Affective Disord 1985;1:S3-S6
   CrossRef | Medline

3. 3

   Tune L, Carr S, Hoag E, Cooper T. Anticholinergic effects of drugs commonly prescribed for the elderly: potential means for assessing risk of delirium. Am J Psychiatry 1992;149:1393-1394
   Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: We are pleased to note that the criteria recently proposed by NINDS and AIREN include senile leukoencephalopathy among the causes of vascular dementia, since we also think that this might be a common factor contributing to dementia in very elderly patients. If we had included it among our criteria, the proportion of subjects with vascular dementia would have been even higher. The NINDS-AIREN criteria also propose an arbitrary limit of three months for the onset of dementia after stroke; this limit would be difficult to apply in prevalence studies, in which dementia has often developed many years before the examination of the patient. We are also pleased to know that in general the NINDS-AIREN criteria are “quite close” to ours, as stated by Drs. Roman and Goldstein.

We appreciate the comments by Dr. Monfort on the possible difference in participation rates between people living in the community and those in institutions and its potential influence on the prevalence of dementia. In response to the question about institutionalization, 13.8 percent of the participants and 10.3 percent of the nonparticipants were institutionalized. The difference was not significant (P = 0.18).

We have considered the possible influence of depression and psychotropic drugs on dementia in detail1,2. The prevalence of depression according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders (third edition, revised)3 in the total sample was 12.6 percent1. There was no difference in the prevalence of depression between subjects with and without dementia, except that subjects with mild dementia had a significantly higher prevalence of depression than those without dementia2. However, subjects with dementia had a high rate of prescription of antidepressant agents (31 percent) and of anxiolytic-sedative agents (38 percent)1.

In the three subjects with depression mentioned in the letter by Dr. Monfort, depression was initially considered a possible cause of their demented behavior. In cases in which depression or the influence of drugs posed problems in the differential diagnosis, the duration, symptoms, and course of the dementia settled the final diagnosis. It should be emphasized that there may also be a risk of mistaking dementia for depression4.

Ingmar Skoog, M.D.
Lars Nilsson, M.D., Ph.D.
University of Gothenburg, S-413 45 Gothenburg, Sweden

Alvar Svanborg, M.D., Ph.D.
University of Illinois, Chicago, IL 60612

4 References

1. 1

   Skoog I, Nilsson L, Landahl S, Steen B. Mental disorders and the use of psychotropic drugs in an 85-year-old representative urban population. Int Psychogeriatrics (in press).
   

2. 2

   Skoog I. The prevalence of psychotic, depressive and anxiety syndromes in demented and non-demented 85-year-olds. Int J Geriatr Psychiatry 1993;8:247-253
   CrossRef | Web of Science

3. 3

   Diagnostic and statistical manual of mental disorders, 3rd ed. rev.: DSM-III-R. Washington, D.C.: American Psychiatric Association, 1987.
   

4. 4

   Reding M, Haycox J, Blass J. Depression in patients referred to a dementia clinic: a three-year prospective study. Arch Neurol 1985;42:894-896
   Web of Science | Medline

Citing Articles (3)

Citing Articles

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   Geng Li, Liangyu Zou, Clifford R. Jack, Yihong Yang, Edward S. Yang. (2007) Neuroprotective effect of Coenzyme Q10 on ischemic hemisphere in aged mice with mutations in the amyloid precursor protein. Neurobiology of Aging 28:6, 877-882
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2. 2

   Geng Li, Liang-Yu Zou, Chun-Mei Cao, Edward S. Yang. (2005) Coenzyme Q10 protects SHSY5Y neuronal cells from beta amyloid toxicity and oxygen-glucose deprivation by inhibiting the opening of the mitochondrial permeability transition pore. BioFactors 25:1-4, 97-107
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3. 3

   Mario F Mendez, Gerald T H Lim. (2003) Seizures in Elderly Patients with Dementia. Drugs & Aging 20:11, 791-803
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