Dementia rates were high in the oldest old, showed an increase with age but no sex differences. Interview methodology has a major impact on results.

In a two-wave community study a representative sample of 402 very old people (older than 85 years) was restudied 1 year later. Four instruments in the clinical examination were used for case identification: (a) the Geriatric Mental State Interview (GMS-A); (b) the Structured Interview for the Diagnosis of Dementia (SIDAM); (c) the Global Deterioration Scale (GDS); and (d) the Mini Mental State Examination (MMSE). The clinical examination was performed by the interviewing physician who made a diagnosis according to DMS-III-R. The focus of the present study is on the (true) incidence of dementia in a representative community sample. The establishment of incidence rates is particularly important for dementia because the prevalence of dementia is affected by the length of survival, which is reduced in dementia and with increasing age. The annual incidence rates per 1000 person years on the basis of the SIDAM DSM-III-R were 116.6 for all cases at risk, 113.6 for those aged 85-89 years, 112.5 for those aged 90-94 years and 235.7 for those aged 95 years and older at first assessment (t1). Incidence rates based on the other methods of assessment are reported. In order to obtain the most meaningful estimate of incidence rates a compound dementia diagnosis was defined. According to this the annual incidence rate per 1000 person years was 144.1 for all persons at risk. The incidence rate tended to be higher in the older-age cohorts: It was 126.2 for those aged 85-89 years, 193.1 for those aged 90-94 years and 295.5 for those aged 95 years and older. In comparison with the literature the incidence rates were high. The results are plausible when the very old age of the sample is taken into account.

In a two-wave community study in Munich, Germany, a representative sample of 402 people older than 85 years was restudied 1 year later. In the first cross section a total of 358 (89.1%) subjects were interviewed. One year later 263 (73.5%) subjects were reexamined. Several diagnostic systems were used. The probands showed a high prevalence of depression--nearly one quarter of the interviewees. In this extreme age group gender differences in depression were minimal. Depressive were distinctly impaired in daily life. Depressive probands were more often found in institutions than in private households. Depressives were high users of the medical care system, but very rarely treated by specialists. Need for care and certain specific especially threatening life events were identified as risk factors for depression.

The incidence rate of depression in very old people was examined. In a two-wave community study of Munich, Germany a representative sample of 402 people older than 85 years was restudied 1 year later. In the first cross section a total of 358 (89%) subjects were interviewed. One year later 263 (73.6%) subjects could be reexamined. Only persons with two examinations were included for analysis of incidence. Several diagnostic systems were used. According to the project diagnosis of 203 persons at risk, 25 subjects suffered 1 year later from depression. The incidence rate amounted to 133.49 per 1000 person years at risk. According to the project diagnosis of 203 persons at risk, 25 subjects suffered 1 year later from depression. The incidence rate amounted to 133.49 per 1000 person years at risk. According to the GMS-A computer AGECAT diagnosis the incidence rate amounted to 140.97 per 1000 person years at risk. The younger age cohort, persons with changing living situations and subjects suffering from dementia in the first cross section had a higher risk for depression. The results were not significant.

Data on cognitive impairment in the oldest old is reported comparing two different samples, one in Munich, Germany, and the other in the United States (Epidemiologic Catchment Area [ECA] study). In both studies the Mini Mental State Examination (MMSE) was used for assessing cognitive impairment. The Munich sample consisted of 402 and the ECA sample of 827 very old people aged 85 years and above. The results indicate that approximately 40% of each sample scored below 24 points in the MMSE indicating at least mild cognitive impairment. Severe cognitive impairment was found in 13.4% of the Munich and in 14.6% of the American sample. The prevalence of major depression was 1.4% in Munich and 2.0% in the ECA study, and dysthymia was found in 5.1% in the Munich and in 2.0% in the ECA sample aged 85 years and above. Persons living in institutions in both studies more frequently showed signs of cognitive impairment than those living in private households. The ECA sample, but not the Munich sample, showed a significantly higher prevalence of cognitive impairment for females and for the oldest age cohort above 90 years of age. Major depression was more frequent in Munich in persons living in institutions and in the ECA study among the oldest age cohort above 90 years of age. Dysthymia in both studies did not show any association with sociodemographic factors. Most of the excess comorbidity (cognitive impairment and depression) was observed among subjects with mild (and not with severe) cognitive impairment.(ABSTRACT TRUNCATED AT 250 WORDS)