The influence of age on the association between cholesterol and cognitive function.

With the increasing emphasis on vascular disease as a risk factor for dementia and cognitive impairment, lowering cholesterol has received much attention to maintain cognitive function. Observational studies have shown that high total serum cholesterol levels in middle age, but not in old age, associate with cognitive impairment in later life. This can be explained in part since the association between high levels of total serum cholesterol levels and cardiovascular disease becomes weaker with increasing age and is absent in old age. Most studies on HDL-cholesterol levels show a protective association with cardiovascular disease up to old age, whereas data on the protective association with late-life cognitive impairment is absent. In contrast to general belief, randomized controlled trials and most longitudinal observational studies do not show a positive effect of statin treatment on the risk of dementia when prescribed in later life. In conclusion, high total serum cholesterol in middle age is associated with cognitive impairment and statin therapy is likely to have a benefit on cognitive function via a decrease of cardiovascular pathologies. However, a beneficial effect of cholesterol lowering on cognitive function in old age is uncertain.