Anthony F. Jorm

Global prevalence of dementia: a Delphi consensus study.

BACKGROUND 100 years after the first description, Alzheimers disease is one of the most disabling and burdensome health conditions worldwide. We used the Delphi consensus method to determine dementia prevalence for each world region. METHODS 12 international experts were provided with a systematic review of published studies on dementia and were asked to provide prevalence estimates for every WHO world region, for men and women combined, in 5-year age bands from 60 to 84 years, and for those aged 85 years and older. UN population estimates and projections were used to estimate numbers of people with dementia in 2001, 2020, and 2040. We estimated incidence rates from prevalence, remission, and mortality. FINDINGS Evidence from well-planned, representative epidemiological surveys is scarce in many regions. We estimate that 24.3 million people have dementia today, with 4.6 million new cases of dementia every year (one new case every 7 seconds). The number of people affected will double every 20 years to 81.1 million by 2040. Most people with dementia live in developing countries (60% in 2001, rising to 71% by 2040). Rates of increase are not uniform; numbers in developed countries are forecast to increase by 100% between 2001 and 2040, but by more than 300% in India, China, and their south Asian and western Pacific neighbours. INTERPRETATION We believe that the detailed estimates in this paper constitute the best currently available basis for policymaking, planning, and allocation of health and welfare resources.

Mild cognitive impairment : beyond controversies, towards a consensus : report of the International Working Group on Mild Cognitive Impairment

The First Key Symposium was held in Stockholm, Sweden, 2–5 September 2003. The aim of the symposium was to integrate clinical and epidemiological perspectives on the topic of Mild Cognitive Impairment (MCI). A multidisciplinary, international group of experts discussed the current status and future directions of MCI, with regard to clinical presentation, cognitive and functional assessment, and the role of neuroimaging, biomarkers and genetics. Agreement on new perspectives, as well as recommendations for management and future research were discussed by the international working group. The specific recommendations for the general MCI criteria include the following: (i) the person is neither normal nor demented; (ii) there is evidence of cognitive deterioration shown by either objectively measured decline over time and/or subjective report of decline by self and/or informant in conjunction with objective cognitive deficits; and (iii) activities of daily living are preserved and complex instrumental functions are either intact or minimally impaired.

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.

The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): socio-demographic correlates, reliability, validity and some norms

The IQCODE is a questionnaire which asks an informant about changes in an elderly persons everyday cognitive function. The questionnaire aims to assess cognitive decline independent of pre-morbid ability. In the present study, the IQCODE was administered to a sample of 613 informants from the general population. In addition, the questionnaire was administered to informants of 309 dementing subjects who had filled it out one year previously. A principal components analysis, using the general population sample, confirmed that the IQCODE measures a general factor of cognitive decline. The questionnaire was found to have high internal reliability in the general population sample (alpha = 0.95) and reasonably high test-retest reliability over one year in the dementing sample (r = 0.75). The total IQCODE score, as well as each of the 26-items, was found to discriminate well between the general population and dementing samples. The correlation with education was quite small (r = -0.13), indicating that contamination by premorbid ability is not a problem.

A short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): development and cross-validation.

Data from four studies were used to assess the psychometric properties of the 26 IQCODE items. The items were assessed in terms of item-total correlations, test-retest reliabilities, correlations with indicators of current cognitive functioning and correlations with indicators of premorbid cognitive functioning. These data were used to develop a 16-item short form. The short form was cross-validated in a new sample using dementia/delirium diagnosis as the validity standard. It was found to perform as well as the long form.

The incidence of dementia A meta-analysis

Objective: To carry out a meta-analysis of the age-specific incidence of all dementias, including AD and vascular dementia. Background: Several meta-analyses have been carried out on dementia prevalence, but none on its incidence. Methods: We used loess-curve fitting to analyze data from 23 published studies reporting age-specific incidence data. Results: The incidence of both dementia and AD rose exponentially up to the age of 90 years, with no sign of leveling off. The incidence rates for vascular dementia varied greatly from study to study, but the trend was also for an exponential rise with age. There was no sex difference in dementia incidence(p = 0.21), but women tended to have a higher incidence of AD in very old age, and men tended to have a higher incidence of vascular dementia at younger ages. East Asian countries had a lower incidence of dementia than Europe (p = 0.0004), and also tended to have a lower incidence of AD. Conclusions: The incidence of dementia rises exponentially to the age of 90 years. Any sex differences are small, and incidence is lower in East Asia than in Europe.

Does old age reduce the risk of anxiety and depression? A review of epidemiological studies across the adult life span

BACKGROUND There is considerable disagreement about what happens to the risk of anxiety and depression disorders and symptoms as people get older. METHODS A search was made for studies that examine the occurrence of anxiety, depression or general distress across the adult life span. To be included, a study had to involve a general population sample ranging in age from at least the 30s to 65 and over and use the same assessment method at each age. RESULTS There was no consistent pattern across studies for age differences in the occurrence of anxiety, depression or distress. The most common trend found was for an initial rise across age groups, followed by a drop. Two major factors producing this variability in results were age biases in assessment of anxiety and depression and the masking effect of other risk factors that vary with age. When other risk factors were statistically controlled, a more consistent pattern emerged, with most studies finding a decrease in anxiety, depression and distress across age groups. This decrease cannot be accounted for by exclusion of elderly people in institutional care from epidemiological surveys or by selective mortality of people with anxiety or depression. CONCLUSION There is some evidence that ageing is associated with an intrinsic reduction in susceptibility to anxiety and depression. However, longitudinal studies covering the adult life span are needed to distinguish ageing from cohort effects. More attention needs to be given to understanding the mechanism behind any ageing-related reduction in risk for anxiety and depression with age. Possible factors are decreased emotional responsiveness with age, increased emotional control and psychological immunization to stressful experiences.

The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): a review

Background and aims: The IQCODE is widely used as a screening test for dementia, particularly where the subject is unable to undergo direct cognitive testing or for screening in populations with low levels of education and literacy. This review draws together research on the psychometric properties and validity of the IQCODE. Method: A systematic search of the literature was carried out using three databases. Results: The review shows that the questionnaire has high reliability and measures a single general factor of cognitive decline. It validly reflects past cognitive decline, performs at least as well at screening as conventional cognitive screening tests, predicts incident dementia, and correlates with a wide range of cognitive tests. A particular strength is that the IQCODE is relatively unaffected by education and pre-morbid ability or by proficiency in the cultures dominant language. The disadvantage of the IQCODE is that it is affected by informant characteristics such as depression and anxiety in the informant and the quality of the relationship between the informant and the subject. Conclusions: Because the IQCODE provides information complementary to brief cognitive tests, harnessing them together can improve screening accuracy.

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.

A short form of the Positive and Negative Affect Schedule : evaluation of factorial validity and invariance across demographic variables in a community sample

Abstract The existence of two nearly-orthogonal dimensions of positive and negative affect was established for a ten-item short form of the Positive and Negative Affect Schedule using confirmatory factor analytic techniques in a large probability sample (n=2651) spanning ages 18 to 79. The factor structure and factor correlations were found to be unchanged with age. A multiple indicators, multiple causes model was used to investigate differences in item responses according to age, sex, education, marital status and financial hardship that could not be accounted for by differences in affect levels between groups. Only one item, excited from the Positive Affect scale, was found to elicit differential responses. While improvements to the Positive Affect scale might be desirable, the Short PANAS can be recommended for use when measures of positive and negative affect are required.