A. S. Henderson

The prevalence of dementia: A quantitative integration of the literature

ABSTRACT— Data from studies of dementia prevalence between 1945 to 1985 were analyzed statistically. Prevalence rates were found to vary as a function of methodological differences between studies. However, despite these differences, the relationship between prevalence and age was found to be consistent across studies, with rates doubling every 5.1 years. Across studies, Alzheimers disease (AD) was found to be more common in women, with a tendency for multi‐infarct dementia (MID) to be more common in men. There were also national differences in the relative prevalence of AD and MID, with MID being more commmon in Japanese and Russian studies, no difference in Finnish and American studies, and an excess of AD in other Western European countries.

A case‐control study of Alzheimer's disease in Australia

We conducted a case-control study of clinically diagnosed Alzheimers disease (AD) on 170 cases aged 52 to 96 years, and 170 controls matched for age, sex and, where possible, the general practice of origin. Trained lay interviewers naive to the hypotheses and to the clinical status of the elderly person carried out risk-factor interviews with informants. Significant odds ratios were found for 4 variables: a history of either dementia, probable AD, or Downs syndrome in a 1st-degree relative, and underactivity as a behavioral trait in both the recent and more distant past. Previously reported or suggested associations not confirmed by this study include head injury, starvation, thyroid disease, analgesic abuse, antacid use (aluminum exposure), alcohol abuse, smoking, and being left-handed.

Using the BIS/BAS scales to measure behavioural inhibition and behavioural activation : Factor structure, validity and norms in a large community sample

Abstract The Behavioural Inhibition System and Behavioural Activation System (BIS/BAS) scales of Carver and White (1994) were used in an Australian community sample of 2725 individuals aged 18–79. Factor analysis of the BIS/BAS items supported the 4-factor structure found by Carver and White, as well as a 2-factor structure reflecting separate behavioural inhibition and behavioural activation systems. The BIS scale was related to neuroticism and negative affectivity, while the BAS scale was related to extraversion and positive affectivity. The BIS scale was less correlated with anxiety and depression symptoms than are neuroticism and negative affectivity scales, probably because it is designed to measure predisposition to anxiety rather than the experience of anxiety. BIS scores were higher in females, while the BAS subscales showed a more complex pattern, with reward responsiveness scores higher in females and drive scores higher in males. Both BIS and BAS scores were lower in older age groups, suggesting the possibility that the behavioural inhibition and behavioural activation systems become less responsive with age.

The course of depression in the elderly : a longitudinal community-based study in Australia

BACKGROUND We report the outcome of depressive states after 3-4 years in a community sample of the elderly. METHODS A sample of 1045 persons aged 70+ years in 1990-1 was re-interviewed after 3.6 years. RESULTS Mortality (21.7%) and refusal or non-availability (10.4%) were higher in those who initially had had a diagnosis or symptoms of depression. Of those with an ICD-10 depressive episode in 1990-1, 13% retained that diagnosis. Of those who were not depressed initially only 2.5% had become cases. Depression was unrelated to age or apolipoprotein E genotype. The best predictors of the number of depressive symptoms at follow-up was the number at Wave 1, followed by deterioration in health and in activities of daily living, high neuroticism, poor current health, poor social support, low current activity levels and high service use. Depressive symptoms at Wave 1 did not predict subsequent cognitive decline or dementia. CONCLUSIONS Non-random sample attrition is unavoidable. ICD-10 criteria yield more cases than other systems, while continuous measures of symptoms confer analytical advantages. Risk factors for depressive states in the elderly have been further identified. The prognosis for these states is favourable. At the community level, depressive symptoms do not seem to predict cognitive decline, as they do in referred series.

Do cognitive complaints either predict future cognitive decline or reflect past cognitive decline? A longitudinal study of an elderly community sample

Data from a two-wave longitudinal study of an elderly community sample were used to assess whether cognitive complaints either predict subsequent cognitive decline or reflect past cognitive decline. Cognitive complaints and cognitive functioning were assessed on two occasions three and a half years apart. Cognitive complaints at Wave 1 were found not to predict future cognitive change on the Mini-Mental State Examination, an episodic memory test or a test of mental speed. Similarly, cognitive complaints at Wave 2 were unrelated to past cognitive changes on these tests after statistically controlling for the effects of anxiety and depression. Furthermore, cognitive complaints did not predict either mortality (after controlling for anxiety and depression) or future dementia. These results are evidence against the inclusion of cognitive complaints in diagnostic criteria for proposed disorders such as age-associated memory impairment, mild cognitive disorder and ageing-associated cognitive decline.

Health, cognitive, and psychosocial factors as predictors of mortality in an elderly community sample.

STUDY OBJECTIVE: To examine whether cognitive and psychosocial factors predict mortality once physical health is controlled. DESIGN: A prospective study of community dwelling elderly. Mortality was assessed over a period of 3-4 years after the baseline assessment of predictors. The data were analysed using the Cox proportional hazards model. SETTING: Canberra and Queanbeyan, Australia. PARTICIPANTS: A sample of 897 people aged 70 or over and living in the community, drawn from the compulsory electoral roll. RESULTS: For the sample as a whole, the significant predictors of mortality were male sex, poor physical health, poor cognitive functioning, and low neuroticism. Men had an adjusted relative risk of mortality of 2.5 compared with women. For the male sub-sample, poor self rated health and a poor performance on a speeded cognitive task were significant predictors, while for women, greater disability, low systolic blood pressure, and a low score on a dementia screening test were the strongest predictors. CONCLUSIONS: Mortality was predicted by physical ill health and poor cognitive functioning. Psychosocial factors such as socioeconomic status, psychiatric symptoms, and social support did not add to the prediction of mortality, once sex, physical health, and cognitive functioning were controlled. Mortality among men was more than twice that of women, even when adjusted for other predictors.

The prevalence of depressive disorders and the distribution of depressive symptoms in later life: a survey using Draft ICD-10 and DSM-III-R

The point prevalence of depressive disorders was estimated in a sample of persons aged 70 years and over, which included both those living in the community and those in institutional settings. Lay interviewers administered the Canberra Interview for the Elderly to the subjects and their informants. The point prevalence of depressive episodes as defined by the Draft ICD-10 diagnostic criteria was 3.3%. The rate for DSM-III-R major depressive disorder was 1.0%. The latter prevalence rate is similar to those reported elsewhere for the elderly. Evidence is accumulating that older persons may indeed have low rates for depressive disorders at the formal case level. Possible reasons for this finding are offered. A scale for depressive symptoms, based exclusively on those specified in Draft ICD-10 and DSM-III-R, showed that the elderly do experience many depressive symptoms. Contrary to expectation, these did not increase with age. The number of depressive symptoms was correlated with neuroticism, poor physical health, disability and a history of previous depression. Attention now needs to be directed to the clinical significance of depressive symptoms below the case level in elderly persons.

Symptoms of depression and anxiety during adult life: evidence for a decline in prevalence with age

BACKGROUND To test the hypothesis that the prevalence, in the general population, of symptoms of depression and anxiety declines with age. METHODS A general population sample of 2725 persons aged 18 to 79 years was administered two inventories for current symptoms of depression and anxiety, together with measures of neuroticism and of exposures that may confer increased risk of such symptoms. RESULTS Symptoms of depression showed a decline with age in both men and women. For anxiety, the decline was statistically significant for women but not consistently so for men. For the risk factors examined, there was a decline with age in the neuroticism score, the frequency of adverse life events, being seriously short of money and having had parents who separated or divorced. Further analysis showed that the association between age and a declining symptom score cannot be entirely attributed to these risk factors, with the single exception of neuroticism. The latter is itself likely to be contaminated by current symptoms. CONCLUSION Unless these findings are due to bias in the sample of those who agreed to participate, they add to the evidence that symptoms of depression and to a lesser extent of anxiety decline in prevalence with age. Some risk factors also decline with age. It now has to be determined if these cross-sectional observations are also to be found in longitudinal data; and what process may underlie this striking change in mental health during adulthood.

Non-linear relationships in associations of depression and anxiety with alcohol use

BACKGROUND Many studies have demonstrated co-morbidity of alcohol abuse/dependence with mood and anxiety disorders but relatively little is known about anxiety and depression across the full continua of alcohol consumption and problems associated with drinking. METHODS Participants from a general population sample (N = 2725) aged 18-80 years completed the Alcohol Use Disorders Identification Test (AUDIT) and four measures of negative affect (two depression and two anxiety symptom scales) included in a self-completion questionnaire. RESULTS High consumption, AUDIT total score, and AUDIT problems score were associated with high negative affect scores in participants under 60 years old (ORs in the range 1.80-2.83). Graphical and statistical analyses using continuous measures of alcohol use/problems and negative affect identified non-linear relationships where abstainers and occasional drinkers, as well as heavy and problem drinkers, were at risk of high anxiety and depression levels. This pattern, however, was not found in those aged > or = 60 years. The U-shaped relationship was not an artefact of abstainers being typical of the general population in their distribution of negative affect. CONCLUSIONS Studies of co-morbidity should acknowledge the possibility of non-linear associations and employ both continuous and discrete measures. Abstainers, as well as heavy drinkers, are at increased risk of symptoms of depression and anxiety disorders. Psychosocial factors may play a role in the U-shaped relationship between alcohol consumption and mortality.

EDUCATION AND DECLINE IN COGNITIVE PERFORMANCE: COMPENSATORY BUT NOT PROTECTIVE

The association between education and cognitive change was investigated in a large community sample of elderly people followed up after 3.6 years. Lower education was predictive of decline on the Mini‐Mental State Examination (MMSE) and on tests of language and knowledge, but not on tests of cognitive speed, memory or reaction time. The effects of education were not attenuated when adjusted for health, disability or activity level. The findings suggest that education slows the rate of decline on crystallized intelligence, but not other cognitive abilities. Education may compensate for neurodegenerative changes rather than protect against them.