Social activity, cognitive decline and dementia risk: a 20-year prospective cohort study.
BACKGROUND
Identifying modifiable lifestyle correlates of cognitive decline and risk of dementia is complex, particularly as few population-based longitudinal studies jointly model these interlinked processes. Recent methodological developments allow us to examine statistically defined sub-populations with separate cognitive trajectories and dementia risks.


METHODS
Engagement in social, physical, or intellectual pursuits, social network size, self-perception of feeling well understood, and degree of satisfaction with social relationships were assessed in 2854 participants from the Paquid cohort (mean baseline age 77 years) and related to incident dementia and cognitive change over 20-years of follow-up. Multivariate repeated cognitive information was exploited by defining the global cognitive functioning as the latent common factor underlying the tests. In addition, three latent homogeneous sub-populations of cognitive change and dementia were identified and contrasted according to social environment variables.


RESULTS
In the whole population, we found associations between increased engagement in social, physical, or intellectual pursuits and increased cognitive ability (but not decline) and decreased risk of incident dementia, and between feeling understood and slower cognitive decline. There was evidence for three sub-populations of cognitive aging: fast, medium, and no cognitive decline. The social-environment measures at baseline did not help explain the heterogeneity of cognitive decline and incident dementia diagnosis between these sub-populations.


CONCLUSIONS
We observed a complex series of relationships between social-environment variables and cognitive decline and dementia. In the whole population, factors such as increased engagement in social, physical, or intellectual pursuits were related to a decreased risk of dementia. However, in a sub-population analysis, the social-environment variables were not linked to the heterogeneous patterns of cognitive decline and dementia risk that defined the sub-groups.
Department of Public Health and Primary Care, University of Cambridge, Cambridge, CB2 0SR, UK. riccardo.marioni@ed.ac.uk.|Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK. riccardo.marioni@ed.ac.uk.
Riccardo E
RE
Marioni
INSERM, Centre INSERM U897, F-33000, Bordeaux, France. Cecile.Proust@isped.u-bordeaux2.fr.|University Bordeaux, ISPED, Centre INSERM U897, F-33000, Bordeaux, France. Cecile.Proust@isped.u-bordeaux2.fr.
Cecile
C
Proust-Lima
INSERM, Centre INSERM U897, F-33000, Bordeaux, France. Helene.Amieva@isped.u-bordeaux2.fr.|University Bordeaux, ISPED, Centre INSERM U897, F-33000, Bordeaux, France. Helene.Amieva@isped.u-bordeaux2.fr.|Service de Neurologie, Department of Clinical Neurosciences, CHU, Pellegrin, 33076, Bordeaux, France. Helene.Amieva@isped.u-bordeaux2.fr.
Helene
H
Amieva
Department of Public Health and Primary Care, University of Cambridge, Cambridge, CB2 0SR, UK. carol.brayne@medschl.cam.ac.uk.
Carol
C
Brayne
MRC Biostatistics Unit, Institute of Public Health, Cambridge, CB2 0SR, UK. fiona.matthews@mrc-bsu.cam.ac.uk.
Fiona E
FE
Matthews
INSERM, Centre INSERM U897, F-33000, Bordeaux, France. Jean-Francois.Dartigues@isped.u-bordeaux2.fr.|University Bordeaux, ISPED, Centre INSERM U897, F-33000, Bordeaux, France. Jean-Francois.Dartigues@isped.u-bordeaux2.fr.|Service de Neurologie, Department of Clinical Neurosciences, CHU, Pellegrin, 33076, Bordeaux, France. Jean-Francois.Dartigues@isped.u-bordeaux2.fr.
Jean-Francois
JF
Dartigues
INSERM, Centre INSERM U897, F-33000, Bordeaux, France. Helene.Jacqmin-Gadda@isped.u-bordeaux2.fr.|University Bordeaux, ISPED, Centre INSERM U897, F-33000, Bordeaux, France. Helene.Jacqmin-Gadda@isped.u-bordeaux2.fr.
Helene
H
Jacqmin-Gadda
D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000453:epidemiology* / Q000523:psychology; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D005602:France / Q000453:epidemiology; D015438:Health Behavior; D006801:Humans; D007398:Interpersonal Relations; D007899:Leisure Activities; D008019:Life Style; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012649:Self Concept; D012944:Social Support