Traditionally, brain atrophy, or cerebral atrophy – the loss of neurons and the connections have been associated with stroke, Alzheimer’s disease, dementia, traumatic brain injury, multiple sclerosis or infections. Recently, a group of Japanese researchers have established a new link between frequency of social contact and brain atrophy in the elderly without dementia [1].
Epidemiological evidence has shown that social isolation is associated with the risk of dementia. Based on that, the authors hypothesized that social isolation is also involved in brain atrophy. To prove this, the study enrolled 8896 eligible individuals (57% female 43% male) of mean age 73 years for brain MRI scans. The intracranial volume (ICV) and total brain volume (TBV) were calculated by a computer programme based on individual MRI scans. The amount of social contact, along with other social factors such as education, employment, medical conditions were separately collected from the survey.
To start with, the proportions of individuals with low education, unemployed work status, hypertension, a smoking habit, alcohol intake, and past histories of stroke and heart disease increased significantly with lower frequency of social contact. On the other hand, in women and individuals that regularly exercise and live alone, the mean values of serum total cholesterol and eGFR, and the median score of Mini-Mental State Exam (MMSE) decreased significantly with lower frequency of social contact. Figure 1 below shows the adjusted means of TBV/ICV compared to the frequency of social contact based on 3 mathematical models (each adjusted for different social and background factors such as age and sex, all p values for trend <0.001). All 3 models indicated that less social contact is significantly associated with lower percentage of TBV – brain atrophy.
Figure 1
In addition, the authors also performed a mediation analysis to assess the extent to which depressive symptoms mediated the association between frequency of social contact and brain atrophy. Overall, 15% – 29% of the total associations between frequency of social contact and each brain volume were found to be mediated by depressive symptoms. On the other hand, the direct effects of the frequency of social contact on each brain volume ranged from 71% to 85%.
Other than brain atrophy, and depressive symptoms, lack of social contact has been linked to multiple other serious health conditions. A 2020 report from National Academies of Science, Engineering, and Medicine (NASEM) pointed out that social isolation significantly increased the risk of dementia, heart disease, risk of stroke, mental health conditions (depression, anxiety and suicide) and significant increase of premature death [2]. To tackle the issue, countries across the world have implemented multiple interventions with a variety of formats and delivery modes [3]. Common strategies deployed including social care provision, animal intervention, befriending intervention, and leisure/skill development [4]. Local adaptability with greater community involvement is one of the few key aspects for programme success.
In conclusion, the new Japanese study published in Neurology successfully established the link between lower frequency of social contact and brain atrophy, which contributes to onset of dementia. Programmes to promote elderly social contacts have been implemented worldwide with various degrees of success. Future studies could follow up on brain changes for those involved in community programmes and investigate their long-term efficacy on elderly health.
References
- Hirabayashi N, Honda T, Hata J, Furuta Y, Shibata M, Ohara T, et al. Association Between Frequency of Social Contact and Brain Atrophy in Community-Dwelling Older People Without Dementia: The JPSC-AD Study. Neurology. 2023 Jul 12;10.1212/WNL.0000000000207602–2.
- National Academies of Sciences E. Social Isolation and Loneliness in Older Adults: Opportunities for the Health Care System [Internet]. nap.nationalacademies.org. National Academies Press; 2020. Available from: https://nap.nationalacademies.org/catalog/25663/social-isolation-and-loneliness-in-older-adults-opportunities-for-the
- Fakoya OA, McCorry NK, Donnelly M. Loneliness and social isolation interventions for older adults: a scoping review of reviews. BMC Public Health [Internet]. 2020 Feb 14;20(1). Available from: https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-020-8251-6
- Gardiner C, Geldenhuys G, Gott M. Interventions to reduce social isolation and loneliness among older people: an integrative review. Health & social care in the community [Internet]. 2018 [cited 2019 Oct 6];26(2):147–57. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27413007
