Incidence of dementia in a population older than 75 years in the United Kingdom.

BACKGROUND: Incidence studies have been relatively neglected in psychiatric epidemiology. They are particularly important for dementia, since prevalence rates are affected by length of survival, which itself falls with increasing age and presence of dementia. METHODS: Two-wave community study of 1195 elderly subjects aged older than 75 years, restudied 2.4 years after a community prevalence study. A two-stage method was used, comprising the Mini-Mental State Examination followed in a stratified sample by the Cambridge Examination for Mental Disorders of the Elderly (CAM-DEX) interview. Incidence rates were based on person-years at risk. RESULTS: Annual incidence rates for dementia were 2.3% for subjects initially aged 75 to 79 years, 4.6% for ages 80 to 84 years, and 8.5% for ages 85 to 89 years, approximately doubling every 5 years. Rates did not differ significantly by sex, educational level, or social class. Twice as many additional individuals received a diagnosis of minimal dementia not reaching case threshold. CONCLUSIONS: The findings show high rates of new onset dementia, increasing markedly with age, and suggest rapid acceleration of one or more processes that is common in advanced age.

The prevalence of depression in a cohort of the very elderly.

In a community study of 1173 very elderly (> or = 77 years) subjects, a screening interview was followed by a CAMDEX diagnostic interview in a subsample of 461. The estimated prevalence of DSM-III-R major depressive disorder in the community sampled was 2.4% (95% CI 0.9%, 4.0%). Using CAMDEX criteria, the prevalence of depressive illness was 3.0% (95% CI 0.7%, 5.3%). 10% of those who had a diagnostic interview were rated as having depressive symptoms of mild or moderate severity. Of these, approximately 1/3 met diagnostic criteria for major depressive disorder. The significance of these findings and the possible need for wider criteria for depression in the elderly are discussed.

Extrapyramidal signs, primitive reflexes and frontal lobe function in senile dementia of the Alzheimer type.

Of 146 elderly subjects suffering from Alzheimer-type dementia, 44% were found to have significant extrapyramidal signs. Although extrapyramidal signs were more common in those who had taken neuroleptic drugs in the preceding six months, 22 subjects (15%) who were drug free also had extrapyramidal signs. Scores for cognitive function and for 'frontal lobe' signs (verbal fluency, evidence of perseveration, and primitive reflexes) were found to correlate well with scores for extrapyramidal signs, suggesting that they reflect changes in a common substratum. It is tentatively suggested that this might be an abnormality in the dopamine system.

Incidence of clinically diagnosed subtypes of dementia in an elderly population. Cambridge Project for Later Life.

BACKGROUND: In developed countries, most dementia appears to be due to Alzheimer's disease and vascular dementia. We report rates for incidence of subtypes of dementia based on clinical diagnosis. METHOD: This study was a 2.4-year (s.d. 2.6 months) follow-up of a cohort aged 75 years and over, seen initially in a prevalence study of dementia. A screening interview in 1173 survivors was followed in a subsample of 461 respondents by a diagnostic interview 1.8 months after screening (s.d. 1.5 months). This comprised a standardised interview with respondent and informant, with venepuncture where possible. Clinical diagnoses of subtypes were made by specified criteria. RESULTS: The incidence of Alzheimer's disease of mild and greater severity was 2.7/1000 person-years at risk (1.6-4.4); in men 1.5 (0.8-2.7) and in women 3.3 (1.8-5.9). The incidence of vascular dementia was 1.2/100 person-years at risk (0.7-1.9); in men 1.1 (0.4-2.8) and in women 1.2 (0.7-2.0). Alzheimer's disease, but not vascular dementia, showed a marked increase with age, particularly in women. Rates for minimal dementia of different subtypes showed similar age and sex effects, but were much higher for Alzheimer's disease than vascular dementia. CONCLUSIONS: The striking rise in incidence rates of dementia in the very old appear to be due to Alzheimer's disease, while rates for vascular dementia remain relatively constant. These trends are particularly marked for minimal dementia, but emphasise the importance of Alzheimer's disease in the community as a cause of cognitive decline of all degrees.

Vascular risks and incident dementia: results from a cohort study of the very old.

The contribution of vascular pathology to the manifestation of dementia and the importance of vascular risk to measures of cognitive function is being increasingly recognized. In particular, confirmation of this risk points towards approaches for prevention in large sections of the population. Information on determinants of incident dementia is increasing, but still relatively few studies of risk have been based on incident cases of dementia in very elderly populations. In this study based on incident cases of dementia in a population aged 75 and over, vascular risks were obtained from informants of the respondents with incident dementia. When compared with controls the factors associated with incident dementia were history of heart attack (odds ratio 2.9), transient ischaemic attacks (4.8), cerebrovascular accidents (3.4), family history of first-degree relatives with dementia (4.0), and occupational exposure to vibrating instruments (1.4). If only Alzheimer's disease, clinically diagnosed, was included, diabetes (1.4) and a history of dementia in first-degree relatives (6.6) emerged. Thus, vascular risk continues to be of importance in the oldest age groups.