Relationship Between Low Levels of High-Density Lipoprotein Cholesterol and Dementia in the Elderly. The InChianti Study

DEMENTIA is a common disease in older individuals living in western societies. In the past years, numerous studies have suggested the existence of a relationship between lipids metabolism and dementia. However, studies that explored the relationship between plasma lipids and dementia have reported conflicting findings. Some (1,2) but not all (3,4) epidemiological studies suggested that elevated total cholesterol (TC) levels in the middle age might be a risk factor for dementia in late life. On the contrary, cross-sectional studies have consistently reported an association between low TC levels and the diagnosis of dementia in the elderly subjects (5–8). High TC levels in late life have been associated with a decreased risk of dementia (9–11); consistently decreasing levels of TC have been associated with dementia in older individuals (12–14). Only a few studies have evaluated the association between dementia and specific lipoprotein fractions, such as low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and non-HDL-C. This is an important issue since apo B–containing lipoproteins (LDL-C or non-HDL-C) and apo A–containing lipoproteins (HDL-C) have “opposite” functions in human physiology and have been associated with a pro- and antiatherogenic profile, respectively. Increased levels of LDL-C have been associated with Alzheimer’s disease (AD; 15,16), as well as dementia with stroke (17), but other studies failed to confirm these associations (8,18). On the contrary, some evidence suggests that low levels of HDL-C or Apo A-I might be associated with dementia in older individuals (19,20), and in particular with vascular dementia (21,22). Accordingly, high HDL-C values appeared to be protective against dementia in some (23) although not all studies (24,25). In the present study, we evaluated the association of different plasma lipid fractions with the prevalence of dementia in a large sample of Italian community-dwelling older individuals.