Alzheimer's disease and vascular brain lesions

Modeling the dementia epidemic

The incidence of dementia increases steeply with age in older people, although from the tenth decade the slope may be smoother, perhaps reflecting different pathological processes in the oldest old. The prevalence depends upon interaction of age with other factors (e.g., comorbidities, genetic or environmental factors) that in turn are subject to change. If onset of dementia could be postponed by modulating its risk factors, this could significantly affect its incidence. Analysis of risk and protection factors should take into account the critical period during which these factors play a role. For example, the impact of education and diabetes mellitus occurs in early- and midlife, respectively, while maintaining optimal physical and mental activity and controlling vascular factors later in life may slow the rate of cognitive decline. Modifying factors need to be evaluated for different clinical groups, taking into account genetic background, age, and duration at exposure. The aim of the present article is to try to take stock of epidemiological data concerning factors affecting the prevalence of dementia and predict future developments, as well as to look for possible interventions that could affect outcome.

Importance of symptomatic cerebral infarcts on cognitive performance in patients with Alzheimer's disease

The coexistence of cerebral infarcts and Alzheimer's disease (AD) is common, but the influence of symptomatic cerebral infarcts on cognition is uncertain in AD. We hypothesize that symptomatic cerebral infarcts may provide an additive cognitive factor contributing to dementia in the AD population. We studied 1,001 clinically probable or possible AD patients in the Alzheimer Disease Research Center (ADRC) database. Linear regression was used to evaluate for an association between symptomatic cerebral infarcts and memory, language, executive function, abstract reasoning, and visuospatial performance, separately. Models were adjusted for covariates including age, gender, education, ethnicity, hypertension, diabetes mellitus, heart disease, clinical dementia rating, the presence of silent cerebral infarcts, and multiplicity or location of infarcts. Clinical history of stroke was present in 107 patients, radiological infarcts in 308 patients, and 68 patients with both were considered to have symptomatic infarcts. Adjusting for all covariates, AD patients with symptomatic infarcts had more impairment of executive function (P < 0.05). The influence of cerebral infarcts is neither general nor diffuse, and the presence of clinical history may have a more important influence on executive performance in AD.

Apolipoprotein E epsilon4 allele genotype and the effect of depressive symptoms on the risk of dementia in men: the Honolulu-Asia Aging Study

CONTEXT

The apolipoprotein E epsilon4 (APOE epsilon4) allele is a genetic risk factor for Alzheimer disease. Recently, depression has also become recognized as a risk factor for dementia. However, the possible effect of the APOE genotype on the association between depression and dementia is unexamined.

OBJECTIVE

To examine the independent and combined effects of depression and APOE epsilon4 on the risk of dementia and its subtypes.

DESIGN

The Honolulu-Asia Aging Study, a population-based prospective cohort study of Japanese American men.

SETTINGS AND PARTICIPANTS

Depressive symptoms and presence of the APOE epsilon4 allele were assessed between March 1991 and October 1993 in 1932 cognitively healthy men aged 71 to 90 years. Incident cases of dementia were diagnosed during approximately 6 years of follow-up based on neurologic assessment at 2 repeated examinations (April 1994-April 1996 and October 1997-February 1999).

MAIN OUTCOME MEASURES

Overall dementia, Alzheimer disease, and vascular dementia.

RESULTS

The interaction of depression and APOE epsilon4 was statistically significant in the analytical models. Compared with men with neither APOE epsilon4 nor depression, the risk of dementia in nondepressed men with APOE epsilon4 was not significant (hazard ratio, 1.1; 95% confidence interval [CI], 0.6-1.8); however, depressed men without APOE epsilon4 had a 1.6-fold greater risk (95% CI, 0.8-3.0), whereas depressed men with APOE epsilon4 had a 7.1-fold greater risk (95% CI, 3.0-16.7) of dementia. For subtypes, we found similar increased risks of Alzheimer disease.

CONCLUSIONS

The APOE epsilon4 status modifies the association between depressive symptoms and dementia in elderly men. Because individuals with depressive symptoms and the APOE epsilon4 allele had a markedly increased risk of dementia, one might be especially watchful for early signs of dementia in the older person with depression who is also positive for the APOE epsilon4 allele. Because this cohort includes only men, further investigation in women is required.

Risk factors for Alzheimer's disease in Russia: a case-control study

No reliable data on risk factors of Alzheimer's disease (AD) are available in Russia. We aimed to evaluate the relative importance of various putative environmental and medical risk factors of AD in a Russian population. We conducted a hospital-based case-control study. Two hundred and sixty consecutive AD patients and an equal number of cognitive impairment-free control subjects matched for sex, age, level of education and place of birth selected from nursing homes and other long-term healthcare facilities in the Novosibirsk region for the period from 1998 to 2002 were examined. A conditional logistic regression analysis was employed to calculate odds ratios (OR) and corresponding 95% confidence intervals (CI) for various putative risk factors. Of the 260 patients with AD, 187 (72%) were females. Patients' age varied from 40 to 89 years (mean +/- SD: 69.2 +/- 7.7 years). The majority of the patients (77%) had secondary education and 12% had university education. Risk factors independently associated with AD were family history of parkinsonism among first-degree relatives (OR = 4.2; 95% CI 1.2-15.1), hypothyroidism (OR = 2.7; 95% CI 1.1-6.7), and history of head trauma with loss of consciousness (OR = 1.7; 95% CI 1.0-2.8). The most important risk factors for AD in the Russian community are family history of parkinsonism, hypothyroidism and a history of head trauma with loss of consciousness. These findings have implications for developing preventive strategies of AD.