Gender differences in the incidence of Alzheimer’s disease : is there an implication for age-related changes in body composition and body fat distribution?

Alzheimer's disease (AD) is the most common cause for dementia amongst the elderly, while vascular dementia (VD) represents the second major one. There is some evidence that women are at higher risk of developing AD than men. Unfortunately, the ethiopathogentic implication of this biological factor is still unclear. It is possible that the differences in the sex effect between dementia and AD are most likely explained by the fact that men are at a higher risk than women for VD. On the other hand, it has been recognized that the presence of a vascular burden (atherosclerosis and inflammation) could be considered a possible cofactor for all dementia syndromes. In this respect, attention has been focused on the presence of a longitudinal link with middle-age adiposity and preliminary investigations have suggested a predominant role for body fat distribution, particularly for intra-abdominal fat accumulation. An increase in total and central obesity usually occurs in older women, especially after the menopause transition and related estrogens deprivation. This has been linked with a number of vascular factors, such as metabolic complications (insulin resistance, dyslipidemia, hypertension) and increased inflammatory background. Along with this, it has also been suggested that lack of estrogen or other hormonal changes in postmenopausal women, either by themselves or in association with other factors, account for the increased risk. In this background of considerations, changes in body composition and fat distribution occurring with estrogen deprivation could reasonably contribute the development of cognitive decline and their role probably deserve further investigations.