Loneliness and Dementia Risk

Abdullah Hashmi, MD

April 07, 2022

The study covered in this summary was published on papers.ssrn.com as a preprint and has not yet been peer reviewed.

Key Takeaways

  • New findings suggest that loneliness is positively associated with dementia.

  • Physiological and behavioral factors like hypertension, inflammation, smoking, excessive alcohol use, and low physical activity have minimal roles as mediators between loneliness and dementia.

Why This Matters

  • Given growing evidence of association, the study analyzed a very large cohort for the longitudinal association of feelings of loneliness with dementia.

  • The study was also one of the first to explore potential underlying mediators of loneliness to understand pathways to dementia.

  • The study provided further evidence that loneliness is a modifiable risk factor for dementia, allowing clinicians and public health officials to account for it in dementia and potentially other illnesses.

  • Dementia affected more than 50 million people worldwide in 2020 and is expected to triple by 2050. One third of individuals in industrialized countries are also affected by loneliness. As people age, they are more likely to feel lonely.

Study Design

  • Drawing data from the UK Biobank, the study retrospectively followed 413,545 participants with or without loneliness for an average of 12 ± 1.6 years. A primary measured outcome of all-cause dementia was self-reported or obtained from health records.

  • A loneliness scale measured loneliness and included participants' answers to subjective questions including, "Do you feel lonely?" and "How often are you able to confide in someone close to you?".

  • Analyses were adjusted for sociodemographic, clinical, and behavioral confounders.

  • Potential mediators between loneliness and depression that were analyzed included hypertension (>140/90 mm Hg or using hypertensive medication), C-reactive protein level (CRP), and unhealthy behaviors including self-reported smoking status, alcohol consumption, and physical activity.

  • Participants with a dementia diagnosis within 3 years of their initial assessment were excluded to eliminate loneliness as potentially a prodromal feature of dementia. Also, participants with missing data in any analytic variable were excluded. 

Key Results

  • Among 413,545 participants, 54% were female and 84% were White, ranging in age from 38-73 years.

  • A total of 32.3% of participants were classified as lonely. Compared with non-lonely participants, a higher proportion of lonely participants were physically inactive (13.2% vs 8.4%), were socially isolated (25.2% vs 10.9%), and sought help for depression (44% vs 30.1%).

  • Being lonely or unable to confide in someone close increased the odds of developing dementia (odds ratio, 1.41). Being lonely and unable to confide in someone increased the odds of developing dementia even further (OR, 1.50).

  • A significant positive association between loneliness and subsequent dementia was found, with higher odds of developing dementia in the lonely population (adjusted odds ratio, 1.39; P < .001).

  • Hypertension and unhealthy behaviors as mediators explained 1% and 2%, respectively, of the effect of loneliness on dementia risk.

  • Baseline CRP levels did not mediate between loneliness and dementia risk.


  • Measurement of variables relied on self-reported data rather than objective measures.

  • Chronic and acute loneliness was unable to be compared because of small numbers of participants reporting this measure in follow-up visits.

  • There was potential for selection bias as the UK Biobank recruited volunteers with a 5.5% response rate.

  • Measurement of CRP is nonspecific and rises can be caused by multiple conditions that may affect correlation with dementia.

  • There was a chance for residual and unmeasured confounding in the longitudinal study.

  • Data on mediators and exposure was obtained at the same timepoint; whether loneliness preceded mediators could not be concluded.


  • The study received no commercial funding.

  • None of the authors disclosed relevant financial relationships.

This is a summary of a preprint research study, "Loneliness as a Risk Factor for Dementia and its Mediators: A Longitudinal Cohort Analysis of UK Biobank Data," written by researchers at University College London, Division of Psychiatry, London, UK on Preprints with the Lancet, provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on papers.ssrn.com.


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