Undifferentiated dementia, Alzheimer's disease and vascular dementia: age- and gender-related incidence in Liverpool. The MRC-ALPHA Study

BACKGROUND

Does incidence of dementia follow the age pattern of prevalence? Is gender a risk factor? Do patterns of incidence differ between dementias?

AIMS

To assess age-specific incidence rates of undifferentiated dementias, Alzheimer's disease and vascular dementia.

METHOD

5222 individuals aged > or = 65 years, were interviewed using the Geriatric Mental State/History and Aetiology Schedule. The AGECAT package was used to identify cases at three interviewing waves at two-year intervals. Diagnoses were made using ICD-10 Research Criteria and validated against neurological and psychological examination, with imaging and neuropathology on unselected subsamples.

RESULTS

Incidence rates of the dementias increase with age. Age patterns are similar between Alzheimer's disease and vascular dementia. Gender appears influential in Alzheimer's disease. In England and Wales, 39,437 new cases of Alzheimer's disease (4.9/1000 person-years at risk); 20,513 of vascular dementia (2.6/1000 person-years) and 155,169 of undifferentiated dementia (19/1000 person-years) can be expected each year.

CONCLUSIONS

Incidence rates for Alzheimer's disease and vascular dementia appear to behave differently, with an increased risk of Alzheimer's disease for women compared to vascular dementia.

Schizophrenia and delusional disorder in older age: community prevalence, incidence, comorbidity, and outcome

The opportunity to assess prevalence, incidence, and outcome of schizophrenia and delusional disorder was provided by an age- and sex-stratified random sample of 5,222 persons age 65 years and over. This sample was chosen from general practitioner lists, and interviewed by psychiatric nurses trained to use the Geriatric Mental State (GMS)-AGECAT computerized diagnostic system. GMS-AGECAT ensured the reliability of the selection of cases between the two waves of the study. A subsample was interviewed by a research psychiatrist. The sample was followed up 2 years later using the same method by interviewers blind to the initial findings. The protocols of all nominated cases and subcases of schizophrenia/paranoid disorder diagnosed by AGECAT were reviewed by a clinician and DSM-III-R diagnoses were made. Refusal rate was 13 percent for initial interviews (wave 1) and 15 percent for reinterview 2 years later (wave 2). The prevalence of DSM-III-R schizophrenia was 0.12 percent (95% confidence interval [CI] 0.04-0.25) and delusional disorder 0.04 percent (95% CI 0.00-0.14). The minimum incidence of schizophrenia for new cases was 3.0 (95% CI 0.00 to 110.70); for new and relapsed cases, 45.0 (95% CI 3.54-186.20); and for delusional disorder, 15.6 (95% CI 0.02-135.10) per 100,000 per year. Two of the five cases with schizophrenia were known to have been first diagnosed before age 65. After 2 years, none of the cases of schizophrenia had recovered fully, but none was deluded at followup. Two had developed dementia. The outcome was bad because they remained cases of some type of psychiatric illness but good because of the improvement in their schizophrenia/delusion disorder symptoms.

The prevalence of dementia, depression and neurosis in later life: the Liverpool MRC-ALPHA Study

Prevalence rates for psychiatric disorders in the elderly are presented from the initial cross-sectional stage of a longitudinal community study of the incidence of dementia in the city of Liverpool. Together with five other centres in the UK the MRC-ALPHA project forms part of the MRC multicentre incidence study of dementia and cognitive decline. An age- and sex-stratified random sample of 5222 subjects aged > or = 65 was interviewed at home using the Geriatric Mental State-AGECAT package to provide computer diagnoses. The overall age-standardized prevalence rates for organic disorder (4.7%) depressive illness (10.0%) and the neuroses (2.5%) are consistent with levels found in previous smaller studies that have used GMS-AGECAT. Each of these diagnoses is more common in females than males. A rise in organic disorder with age is confirmed as continuing into the oldest age groups for both sexes. An apparent decline with age observed for depression and neurosis diagnoses disappears when organic cases are excluded from the analysis.

Alzheimer's disease, other dementias, depression and pseudodementia: prevalence, incidence and three-year outcome in Liverpool

A group of 1070 community-living persons aged 65 and over was assessed using the GMS-AGECAT package and other interviews at years 0 and 3. Year 3 interviewers were 'blind' to the findings at year 0, and the prevalence of organic disorders and depression was very similar in both years. According to the results at year 3, minimum and maximum prevalence figures for dementia at year 0 were 2.4% and 3.8% for moderate to severe and 0.4% and 2.4% for mild or early cases, with a best estimate of 3.5% and 0.8%, or 4.3% overall, divided into: senile, Alzheimer's type 3.3%; vascular 0.7%; and alcohol-related 0.3%. The overall incidence of dementia, clinically confirmed by six-year follow-up, was 9.2/1000 per year (Alzheimer type 6.3, vascular 1.9, alcohol related 1.0). Three years later, 72.0% of those with depressive psychosis and 62.3% of those with depressive neurosis were either dead or had some kind of psychiatric illness. Nearly 60% of milder depressive cases (7.2% of the total sample) had either died or developed a chronic mental illness. The outcome of depressive pseudodementias is equivocal so far. Findings at year 3 provide validation of AGECAT computer diagnosis against outcome; organic and depression diagnoses are seen to have important implications for prognosis.

The natural history of neurotic disorder in an elderly urban population. Findings from the Liverpool longitudinal study of continuing health in the community

A random community sample of 1070 subjects aged 65 years and over was interviewed at home using the GMS-AGECAT package and followed up three years later. Neurotic symptoms were common, but symptoms sufficient to reach 'case' level were much less frequent. The overall prevalence of neurotic 'cases' was 2.4% in year 0 and 1.4% in year 3. The incidence was estimated as a minimum of 4.4 per 1000 per year over the age of 65. Women were more likely to be 'cases' than men but not 'subcases', and there was a general decline in prevalence with increasing age, particularly for 'subcases'. Anxiety was the commonest neurotic subtype. After three years, 'cases' were shown not to persist, but this did not reflect wellness. There was a tendency still to have some symptoms, but the predominant symptom appeared to change, suggesting a possible chronic neurotic disorder with changing presentation over time. Depressive symptoms were closely associated with this presentation, suggesting that depression may be an important and integral part of a general, changing neurotic disorder.

Alpha: the Liverpool MRC Study of the incidence of dementia and cognitive decline

The design and methods of this longitudinal study of dementia which is underway are described. An age- and sex-stratified random sample of 6,000 elderly community subjects are being re-assessed after a 2-year interval using the GMS-AGECAT package. Alpha forms part of the MRC funded UK multicentre incidence study and an international network of collaborative studies using comparable measures.