The complex role of having confidant on the development of Alzheimer's disease in a community-based cohort of older people in Brazil.

Background: Social interaction is a lifestyle factor associated with a decreased risk of dementia in several studies. However, specific aspects of these social factors influencing dementia are unknown. This study aimed at evaluating the role of the distinct aspects of social support on the incidence of dementia in a community-based cohort of older people in Brazil.

Methods: A total of 345 healthy and independent elderly subjects living in the community were followed by 12 years. Incident cases of dementia and probable Alzheimer's disease were defined by DSM-IV criteria and NINCDS-ADRDA criteria, respectively. Social variables evaluated were marital status, living arrangement, living children, living sibling, confidant and attending recreational groups. Sex, age, education, Mini-Mental State Examination (MMSE) score, depressive symptoms and family income were entered as co-variates in a Cox proportional hazard model.

Results: The absence of confidant was the only social variable associated to higher risk of developing dementia (HR = 5.31; p < 0.001), even after adjustment for age (HR = 1.08; p = 0.048) and baseline MMSE score (HR = 0.79; p = 0.002).

Conclusions: Our data suggest that to have a confidant could be an important lifestyle factor associated with dementia.