Age- and gender-specific prevalence of depression in latest-life--systematic review and meta-analysis

OBJECTIVE

The objective of the study is to systematically analyze the prevalence of depression in latest life (75+), particularly focusing on age- and gender-specific rates across the latest-life age groups.

DESIGN

Relevant articles were identified by systematically searching the databases MEDLINE, Web of Science, Cochrane Library and Psycinfo and relevant literature from 1999 onwards was reviewed. Studies based on the community-based elderly population aged 75 years and older were included. Quality of studies was assessed. Meta-analysis was performed using random effects model.

RESULTS

24 studies reporting age- and gender-specific prevalence of depression were found. 13 studies had a high to moderate methodical quality. The prevalence of major depression ranged from 4.6% to 9.3%, and that of depressive disorders from 4.5% to 37.4%. Pooled prevalence was 7.2% (95% CI 4.4-10.6%) for major depression and 17.1% (95% CI 9.7-26.1%) for depressive disorders. Potential sources of high heterogeneity of prevalence were study design, sampling strategy, study quality and applied diagnostics of latest life depression.

CONCLUSIONS

Despite the wide variation in estimates, it is evident that latest life depression is common. To reduce variability of study results, particularly sampling strategies (inclusion of nursing home residents and severe cognitively impaired individuals) for the old age study populations should be addressed more thoroughly in future research.

Impact of impairment in instrumental activities of daily living and mild cognitive impairment on time to incident dementia: results of the Leipzig Longitudinal Study of the Aged

BACKGROUND

Early diagnosis of dementia requires knowledge about associated predictors. The aim of this study was to determine the impact of mild cognitive impairment (MCI) and impairment in instrumental activities of daily living (IADL) on the time to an incident dementia diagnosis.

METHOD

Data were derived from the Leipzig Longitudinal Study of the Aged (LEILA75+), a population-based study of individuals aged ≥75 years. Kaplan-Meier survival analysis was used to determine time to incident dementia. Cox proportional hazards models were applied to determine the impact of MCI and IADL impairment on the time to incident dementia.

RESULTS

In total, 180 (22.0%) of 819 initially dementia-free subjects developed dementia by the end of the study. Mean time to incident dementia was 6.7 years [95% confidence interval (CI) 6.5-6.9]. MCI combined with IADL impairment was associated with a higher conversion rate to dementia, a shorter time to clinically manifest diagnosis and a lower chance of reversibility to cognitive normal. The highest risk for a shorter time to incident dementia was found for amnestic MCI combined with IADL impairment. The mean time to incident dementia was 3.7 years (95% CI 2.9-4.4) and thus half as long as in subjects without MCI and IADL impairment.

CONCLUSIONS

Subjects with MCI and IADL impairment constitute a high-risk population for future dementia. The consideration of both--MCI and IADL impairment-- might help to improve the prediction of dementia.

Risk factors for incident mild cognitive impairment--results from the German Study on Ageing, Cognition and Dementia in Primary Care Patients (AgeCoDe)

OBJECTIVES

To provide age- and gender-specific incidence rates of MCI among elderly general practitioner (GP) patients (75+ years) and to identify risk factors for incident MCI.

METHOD

Data were derived from the longitudinal German Study on Ageing, Cognition and Dementia in Primary Care Patients (AgeCoDe). Incidence was calculated according to the 'person-years-at-risk' method. Risk factors were analysed using multivariate logistic regression models.

RESULTS

During the 3-year follow-up period, 350 (15.0%) of the 2331 patients whose data were included in the calculation of incidence developed MCI [person-years (PY) = 6198.20]. The overall incidence of MCI was 56.5 (95% confidence interval = 50.7-62.7) per 1000 PY. Older age, vascular diseases, the apoE epsilon4 allele and subjective memory complaints were identified as significant risk factors for future MCI.

CONCLUSION

Mild cognitive impairment is frequent in older GP patients. Subjective memory complaints predict incident MCI. Especially vascular risk factors provide the opportunity of preventive approaches.

Apolipoprotein E allele 4 is not a sufficient or a necessary predictor of the development of Mild Cognitive Impairment

The presence of Mild Cognitive Impairment (MCI) and of an apolipoprotein E (apoE) varepsilon4 allele both predict the development of Alzheimer's disease. However, the extent to which this allele also predicts the development of MCI is unclear even though MCI is an early transitional stage in the development of Alzheimer's disease. The present study investigates the prevalence of the apoE varepsilon4 allele in incipient MCI. Participants were recruited from the population-based Leipzig Longitudinal Study of the Aged (LEILA75+). All subjects who were initially cognitively healthy, i.e. did not meet MCI criteria described by Petersen [Petersen RC. Mild cognitive impairment. J Intern Med 2004; 256(3): 183-94], and whose apoE status could be determined were followed-up. After 4.5 years, 15.5% of the cognitively healthy target population had developed MCI. The frequencies of the apoE varepsilon4 genotype did not differ between individuals with incipient MCI (12.9%) and individuals who remained cognitively healthy during the study (18.4%, p>0.5). Consequently, the apoE varepsilon4 genotype is not a necessary or sufficient risk factor for MCI. Further studies need to investigate the influence of the whole range of genetic and environmental risk factors on the course of Alzheimer's disease including the initial development of MCI and the later conversion to Alzheimer's disease.