Vascular risk factors, ApoE ?4 allele, and gender and the risk of Alzheimer's disease: perspectives on prevention

Gender and incidence of dementia in the Framingham Heart Study from mid-adult life

BACKGROUND

Gender-specific risks for dementia and Alzheimer's disease (AD) starting in midlife remain largely unknown.

METHODS

Prospectively ascertained dementia/AD and cause-specific mortality in Framingham Heart Study (FHS) participants was used to generate 10- to 50-year risk estimates of dementia/AD on the basis of the Kaplan-Meier method (cumulative incidence) or accounting for competing risk of death (lifetime risk [LTR]).

RESULTS

Overall, 777 cases of incident dementia (601 AD) occurred in 7901 participants (4333 women) over 136,266 person-years. Whereas cumulative incidences were similar in women and men, LTRs were higher in women older than 85 years of age. LTR of dementia/AD at age 45 was 1 in 5 in women and 1 in 10 in men. Cardiovascular mortality was higher in men with rate ratios decreasing from approximately 6 at 45 to 54 years of age to less than 2 after age 65.

CONCLUSION

Selective survival of men with a healthier cardiovascular risk profile and hence lower propensity to dementia might partly explain the higher LTR of dementia/AD in women.

Apolipoprotein E-dependent accumulation of Alzheimer disease-related lesions begins in middle age

OBJECTIVE

To study the prevalence and age dependency of senile plaques (SP) and neurofibrillary tangles (NFT), the brain changes characteristic of Alzheimer disease (AD), and their association with apolipoprotein E (APOE) genotypes in a community-dwelling normal population.

METHODS

This neuropathological study used both silver staining and A beta immunohistochemistry in brain tissue microarrays, including SP coverage and NFT counts from frontal cortex and hippocampus, and APOE genotyping, and was performed on a consecutive prospective series of 603 subjects (aged between 0 and 97 years) of an unselected population living outside of institutions. Cases were subjected to autopsy following sudden or unexpected out-of-hospital death, covering 22.1% of the mortality of Tampere, Finland and its surroundings. None died of AD, although 22 (3.7%) were demented and 10 (1.7%) had memory problems.

RESULTS

Of the series, 30.8% had SP, and 42.1% had NFT; these occurred more commonly among females and showed a strong relationship with age. Both changes had already appeared at around 30 years of age, reaching an occurrence of almost 100% in the oldest. SP were more frequent in APOE epsilon 4-carriers compared with noncarriers in every age group except the oldest (>90 years). The difference was most evident during the ages 50 to 59 years, where 40.7% of epsilon 4-carriers had SP, compared with 8.2% in noncarriers (odds ratio, 8.39; 95% confidence interval, 2.55-27.62). The difference in NFT prevalence between APOE genotypes was not statistically significant in any age group.

INTERPRETATION

The brain changes associated with AD may already begin developing early in middle age, especially among APOE epsilon 4 carriers.

Midlife Neuroticism and the age of onset of Alzheimer's disease

BACKGROUND

There may be important public health implications of increasing our knowledge of factors associated with age of dementia onset. The pre-morbid personality domain of Neuroticism constituted an interesting and theoretically plausible, yet uninvestigated, candidate for such an association. We aimed to examine whether midlife Neuroticism was associated with earlier age of onset of Alzheimer's disease (AD).

METHOD

This was a case-comparison study of 213 patients with probable AD. Detailed clinical information was collected for all patients including age of onset of dementia symptoms. One or two knowledgeable informants rated each patient's midlife personality retrospectively using the Neuroticism, Extraversion, Openness Five-Factor Inventory (NEO-FFI) questionnaire. The relationship between midlife Neuroticism and age of dementia onset was evaluated using both correlational analysis and backward linear regression analysis.

RESULTS

Midlife Neuroticism predicted younger age of dementia onset in females but not in males. The association found in females was independent of pre-morbid history of affective disorder.

CONCLUSIONS

This finding and its potential mechanism warrant further investigation.

Vascular factors and prevention of dementia

The identification of modifiable risk factors that prevent dementia or slow its progression is a major public health priority. Vascular disease and its risk factors have been linked with cognitive decline and dementia, although the degree of association varies depending on differences in vulnerability related to age, ethnicity, disease co-morbidity and possibly brain reserve. Here we review current dementia prevention strategies linked to vascular modification to identify whether any approach exists that will reduce the population burden of dementia, and whether any exist that show evidence of being cost effective and safe for populations. As yet, there is no compelling evidence that dementia can be prevented through vascular manipulation by pharmacological or non-pharmacological trials. To date, no intervention can be recommended for dementia prevention at the population level including Alzheimer's Disease or Vascular Dementia. Advances in the prevention of dementia will be gained, it is argued, from a more complete understanding of the pathophysiology of disease and its causes, particularly in early life, within and across different populations and age groups. Furthermore, a more complete understanding of the earliest pre-clinical stage of disease is required for effective risk factor modification. Although the current state of knowledge cannot support public health policy for vascular manipulation for dementia prevention at the population level, this does not undermine the importance of vascular manipulation in its own right to promote healthier ageing.

Impact of hypertension and apolipoprotein E4 on poststroke cognition in subjects >75 years of age

BACKGROUND AND PURPOSE

The apolipoprotein E4 allele (APOE4) associates with increased dementia risk, and hypertension may associate with mild cognitive deficits. We examined whether nondemented stroke patients with (1) a prestroke history of hypertension and (2) APOE4 were more cognitively impaired at 3 months after stroke.

METHODS

A total of 257 participants were genotyped and outcomes from neuropsychological evaluations analyzed using regression.

RESULTS

Total Cambridge Assessment for Mental Disorders in the Elderly (CAMCOG) and speed of working memory significantly associated with hypertension. No outcomes significantly associated with APOE4.

CONCLUSIONS

Subjects with prestroke hypertension had more impaired global cognition and slower access to information held in working memory.