Paquid is an epidemiological study designed to gather and follow-up a cohort of 3,777 elderly subjects (65 years and older) living at home. In order to study normal and pathological brain ageing, these subjects were randomly chosen in the general population of 75 communities of Gironde and Dordogne, two administrative areas of South-Western France. The subjects were interviewed at home by trained psychologists and followed-up with the same procedure at 1,3 and 5 years after the initial data collection. The identification of the demented cases is made with a two-stage design: the first stage is a systematic screening by the psychologists with application of the DSM-IIIR criteria and the second stage consists in a confirmation of the diagnosis by a neurologist according to the NINCDS-ADRDA criteria. Paquid is complemented by the study of a random sample of 357 subjects riving in institutions in Gironde.

We confirmed an association between marital status and AD, with an excess risk observed among never-married individuals. This association may provide clues about the pathogenesis of AD.

In this large sample of prevalent PD patients and population-matched controls, PD significantly aggregates in families, with the strength of the association being age-dependent. Therefore, familial factors, which can be genetic, environmental, or both, play a role in PD.