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Associations between social connections and cognition: a global collaborative individual participant data meta-analysis

Samtani S 1 , Mahalingam G 2 , Lam BCP 2 , Lipnicki DM 2 , Lima-Costa MF 3 , Blay SL 4 Show all authors , Castro-Costa E 3 , Shifu X 5 , Guerchet M 6 , Preux PM 6 , Gbessemehlan A 6 , Skoog I 7 , Najar J 7 , Rydberg Sterner T 8 , Scarmeas N 9 , Kim KW 10 , Riedel-Heller S 11 , Röhr S 12 , Pabst A 11 , Shahar S 13 , Numbers K 2 , Ganguli M 14 , Jacobsen E 15 , Hughes TF 16 , Crowe M 17 , Ng TP 18 , Maddock J 19 , Marseglia A 20 , Mélis R 21 , Szcześniak D 22 , Wiegelmann H 23 , Vernooij-Dassen M 24 , Jeon YH 25 , Sachdev PS 2 , Brodaty H 2 , SHARED consortium for the Cohort Studies of Memory in an International Consortium (COSMIC)

Affiliations 

  • 1 Centre for Healthy Brain Ageing, Discipline of Psychiatry, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia. Electronic address: s.samtani@unsw.edu.au
  • 2 Centre for Healthy Brain Ageing, Discipline of Psychiatry, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
  • 3 Center for Studies in Public Health and Aging, René Rachou Research Center, Oswaldo Cruz Foundation, Belo Horizonte, Brazil
  • 4 Department of Psychiatry, Federal University of São Paulo, São Paulo, Brazil
  • 5 Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiaotong University School of Medicine, Shanghai, China
  • 6 Inserm U1094, IRD UMR270, University of Limoges, CHU Limoges, Epidemiology of Chronic Diseases in Tropical Zone, Institute of Epidemiology and Tropical Neurology, OmegaHealth, Limoges, France
  • 7 Department of Psychiatry and Neurochemistry, Neuropsychiatric Epidemiology Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Centre for Ageing and Health, University of Gothenburg, Mölndal, Sweden; Psychiatry, Cognition and Old Age Psychiatry Clinic, Sahlgrenska University Hospital, Gothenburg, Sweden
  • 8 Department of Psychiatry and Neurochemistry, Neuropsychiatric Epidemiology Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Centre for Ageing and Health, University of Gothenburg, Mölndal, Sweden
  • 9 1st Department of Neurology, Aiginition University Hospital of Athens, National and Kapodistrian University of Athens, Athens, Greece; Taub Institute for Research in Alzheimer's Disease and the Aging Brain, The Gertrude H Sergievsky Center, Department of Neurology, Columbia University, New York, NY, USA
  • 10 Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, South Korea; Department of Psychiatry, Seoul National University College of Medicine and Department of Brain and Cognitive Science, College of Natural Sciences, Seoul National University, Seoul, South Korea
  • 11 Institute of Social Medicine, Occupational Health and Public Health, Faculty of Medicine, University of Leipzig, Leipzig, Germany
  • 12 Institute of Social Medicine, Occupational Health and Public Health, Faculty of Medicine, University of Leipzig, Leipzig, Germany; Global Brain Health Institute, Trinity College Dublin, Dublin, Ireland
  • 13 Centre for Healthy Aging and Wellness, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
  • 14 Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Epidemiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
  • 15 Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
  • 16 Department of Sociology, Anthropology, and Gerontology, Youngstown State University, Youngstown, OH, USA
  • 17 Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA
  • 18 Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
  • 19 MRC Unit for Lifelong Health and Ageing, University College London, London, UK
  • 20 Division of Clinical Geriatrics, Centre for Alzheimer Research, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden
  • 21 Department of Geriatrics, Radboud University Medical Centre, Nijmegen, Netherlands
  • 22 Department of Psychiatry, Wroclaw Medical University, Wroclaw, Poland
  • 23 Department of Health Care Research, Institute of Public Health and Nursing Research, University of Bremen, Bremen, Germany
  • 24 Faculty of Medical Sciences, Radboud University, Nijmegen, Netherlands
  • 25 Susan Wakil School of Nursing and Midwifery, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
Lancet Healthy Longev, 2022 Nov;3(11):e740-e753.
PMID: 36273484 DOI: 10.1016/S2666-7568(22)00199-4

Abstract

BACKGROUND: Poor social connections (eg, small networks, infrequent interactions, and loneliness) are modifiable risk factors for cognitive decline. Existing meta-analyses are limited by reporting aggregate responses, a focus on global cognition, and combining social measures into single constructs. We aimed to investigate the association between social connection markers and the rate of annual change in cognition (ie, global and domain-specific), as well as sex differences, using an individual participant data meta-analysis.

METHODS: We harmonised data from 13 longitudinal cohort studies of ageing in North America, South America, Europe, Africa, Asia, and Australia. Studies were eligible for inclusion if they had baseline data for social connection markers and at least two waves of cognitive scores. Follow-up periods ranged from 0 years to 15 years across cohorts. We included participants with cognitive data for at least two waves and social connection data for at least one wave. We then identified and excluded people with dementia at baseline. Primary outcomes were annual rates of change in global cognition and cognitive domain scores over time until final follow-up within each cohort study analysed by use of an individual participant data meta-analysis. Linear mixed models within cohorts used baseline social connection markers as predictors of the primary outcomes. Effects were pooled in two stages using random-effects meta-analyses. We assessed the primary outcomes in the main (partially adjusted) and fully adjusted models. Partially adjusted models controlled for age, sex, and education; fully adjusted models additionally controlled for diabetes, hypertension, smoking, cardiovascular risk, and depression.

FINDINGS: Of the 40 006 participants in the 13 cohort studies, we excluded 1392 people with dementia at baseline. 38 614 individual participants were included in our analyses. For the main models, being in a relationship or married predicted slower global cognitive decline (b=0·010, 95% CI 0·000-0·019) than did being single or never married; living with others predicted slower global cognitive (b=0·007, 0·002-0·012), memory (b=0·017, 0·006-0·028), and language (b=0·008, 0·000-0·015) decline than did living alone; and weekly interactions with family and friends (b=0·016, 0·006-0·026) and weekly community group engagement (b=0·030, 0·007-0·052) predicted slower memory decline than did no interactions and no engagement. Never feeling lonely predicted slower global cognitive (b=0·047, 95% CI 0·018-0·075) and executive function (b=0·047, 0·017-0·077) decline than did often feeling lonely. Degree of social support, having a confidante, and relationship satisfaction did not predict cognitive decline across global cognition or cognitive domains. Heterogeneity was low (I2=0·00-15·11%) for all but two of the significant findings (association between slower memory decline and living with others [I2=58·33%] and community group engagement, I2=37·54-72·19%), suggesting robust results across studies.

INTERPRETATION: Good social connections (ie, living with others, weekly community group engagement, interacting weekly with family and friends, and never feeling lonely) are associated with slower cognitive decline.

FUNDING: EU Joint Programme-Neurodegenerative Disease Research grant, funded by the National Health and Medical Research Council Australia, and the US National Institute on Aging of the US National Institutes of Health.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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