Cognitive impairment is an invalidating condition and its prevalence increases significantly with age. It is very important to identify the risk factors for cognitive impairment. Aside from age, sex, familiary history and educational level, the other major risk factors (hypertension, hypercolesterolemia, diabetes mellitus and tobacco), known to be associated frequently with different cerebrovascular diseases, might also contribute to degenerative forms of cognitive impairment because they might favour cerebral microvascular alterations with hypoperfusion, demyelinization and ischemic lesions of subcortical white matter. Longitudinal epidemiological studies detected that arterial hypertension, hypercolesterolemia and tobacco are frequently associated with degenerative forms of cognitive impairment. Some studies show there is no relationship between cognitive impairment and diabetes mellitus, while other underline its role; light alcohol drinking might protect against cognitive impairment. Other recently identified risk factors might be hyperhomocysteinemia and high C-reactive protein blood levels because they seem to be associated with cognitive impairment.