What aspects of social network are protective for dementia? Not the quantity but the quality of social interactions is protective up to 15 years later.
OBJECTIVE
To test the association between several social networks variables reflecting both structural characteristics and quality of relationships with the risk of dementia and Alzheimer's disease 5 and up to 15 years later.


METHODS
The study sample is gathered from the Paquid cohort, a French population-based study of 3,777 elderly people evaluated at baseline and regularly revisited during a 15-year interval. The sample consisted of 2,089 subjects who completed the social network questionnaire and were free of dementia at the time of enrollment and also at the next two follow-ups to minimize the problem of reverse causality. The questionnaire collected at baseline included marital status, number of ties, nature of social network, satisfaction, perception of being understood/misunderstood, and reciprocity in relationships.


RESULTS
The incident cases of dementia considered were those diagnosed at 5-year and subsequent follow-ups, resulting in 461 dementia and 373 Alzheimer's disease cases. The multivariate Cox model, including the six social network variables and adjusted for numerous potential confounders, showed significant associations with satisfaction and reciprocity in relationships. Participants who felt satisfied with their relations had a 23% reduced dementia risk. Participants who reported that they received more support than they gave over their lifetime had a 55% and 53% reduced risk for dementia and Alzheimer's disease, respectively.


CONCLUSIONS
The only variables associated with subsequent dementia or Alzheimer's disease were those reflecting the quality of relationships. The delay between social network assessment and dementia diagnosis was from 5 up to 15 years, thus minimizing the problem of reverse causality.
Amieva
Hélène
H
INSERM, U897, Université Victor Ségalen Bordeaux 2, 146 rue Léo-Saignat, F-33076 Bordeaux Cedex, France. Helene.Amieva@isped.u-bordeaux2.fr
Stoykova
Ralitsa
R
Matharan
Fanny
F
Helmer
Catherine
C
Antonucci
Toni C
TC
Dartigues
Jean-François
JF
D000203:Activities of Daily Living; D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000517:prevention & control* / Q000523:psychology*; D003704:Dementia / Q000175:diagnosis / Q000517:prevention & control* / Q000523:psychology*; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D008137:Longitudinal Studies; D008297:Male; D017063:Outcome Assessment, Health Care; D010549:Personal Satisfaction; D011446:Prospective Studies; D011788:Quality of Life; D012307:Risk Factors; D012944:Social Support; D011795:Surveys and Questionnaires