The frequency of a genetic susceptibility vascular factor, the deletion (D) allele of the angiotensin I converting enzyme gene (ACE), coding for a key enzyme of the renin angiotensin system, was characterized in two independent case-control studies. The results of the current study suggest that bearing at least one ACE D allele is a risk factor to develop dementia for subjects older than 74 years. This observation reinforces the hypothesis of a major implication of vascular risk factors in the occurrence of all types of dementia.