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Loneliness and the Risk of Dementia

Loneliness and the Risk of Dementia

Loneliness is the perception that our social and emotional relationships are not as strong as our desired social and emotional relationships. Social isolation, on the other hand, is an objective measure of solitude and may or may not be distressing. It is estimated that nearly one-third to one-half of elderly individuals may experience social isolation or loneliness [1]. In addition to the detrimental effect loneliness may have on general well-being, loneliness in elderly individuals may also be associated with an increased risk of dementia [2].

Researchers in Spain conducted a meta-analysis of published observational studies that examined whether loneliness is associated with an increased risk of dementia. A meta-analysis combines data from many studies to draw a strong overall conclusion. The researchers compiled eight observational studies conducted in Asia, the United States, and Europe. They found that loneliness was associated with a 26% increased risk of dementia. Additionally, one study found that loneliness was associated with a 105% increased risk of mild cognitive impairment, a precursor to dementia.

The authors acknowledge that our understanding of the relationship between loneliness and dementia risk is not as well understood as other risk factors for dementia (such as diabetes or lack of education). However, they propose some ways that loneliness may influence the risk of dementia. Lonely individuals may engage in poor health behaviors, such as lack of exercise, poor dietary choice, or substance abuse. Also, loneliness is closely associated with depression, itself a risk factor for Alzheimer's disease. Research also suggests that cognitive activity may reduce the risk for dementia, and lonely individuals may suffer from a lack of cognitive stimulation with others.

Additionally, loneliness may have a direct impact on the brain. It may increase stress or affect sleep which could have an influence on brain health. In fact, two recent studies showed that cognitively healthy individuals who had an increased perception of loneliness had higher levels of amyloid and tau, two proteins that accumulate in the brain of Alzheimer's patients [3][4].

There are a few things to keep in mind when interpreting this recent meta-analysis. As with all observational studies, you cannot definitively conclude that loneliness causes Alzheimer's disease. For instance, observational studies are prone to reverse causation—amyloid accumulates in the brain over more than a decade, and it is possible that these changes in the brain could impact the feeling of loneliness. Additionally, perceived loneliness can change over time, and the studies included in the meta-analysis did not examine the persistence of loneliness. On the other hand, loneliness may be a risk factor for death, and if individuals who were lonely died before a diagnosis of dementia, the risk of dementia may be underestimated [5].

Research suggests that some of the most effective programs to reduce loneliness have had high adaptability to the local community, were developed by elderly individuals within the community, and involved productive engagement of elderly individuals within the group [6]. Group activities such as indoor gardening, visual art discussions, or physical exercise groups may benefit brain health while reducing loneliness. Individual activities such as having a pet or one-on-one videoconferencing with family members may also reduce loneliness [7]. Throughout life it is important to maintain connections with friends and family members. Group activities may be found through local community centers, volunteering opportunities with local charities, or through online resources such as Meetup.com. Reducing loneliness not only promotes brain health, it is important for our overall well-being, especially as we age.


  1. Landeiro F, Barrows P, Nuttall Musson E et al. (2017) Reducing social isolation and loneliness in older people: a systematic review protocol. BMJ Open 7, e013778.
  2. Lara E, Martin-Maria N, De la Torre-Luque A et al. (2019) Does loneliness contribute to mild cognitive impairment and dementia? A systematic review and meta-analysis of longitudinal studies. Ageing Res Rev.
  3. d'Oleire Uquillas F, Jacobs HIL, Biddle KD et al. (2018) Regional tau pathology and loneliness in cognitively normal older adults. Transl Psychiatry 8, 282.
  4. Donovan NJ, Okereke OI, Vannini P et al. (2016) Association of Higher Cortical Amyloid Burden With Loneliness in Cognitively Normal Older Adults. JAMA Psychiatry 73, 1230-1237.
  5. Holt-Lunstad J, Smith TB, Baker M et al. (2015) Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspect Psychol Sci 10, 227-237.
  6. Gardiner C, Geldenhuys G, Gott M (2018) Interventions to reduce social isolation and loneliness among older people: an integrative review. Health Soc Care Community 26, 147-157.
  7. Cohen-Mansfield J, Perach R (2015) Interventions for alleviating loneliness among older persons: a critical review. Am J Health Promot 29, e109-125.

Nick McKeehan is Assistant Director, Aging and Alzheimer's Prevention at the Alzheimer’s Drug Discovery Foundation. He served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. He received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. Mr. McKeehan also writes about the biotechnology industry for 1st Pitch Life Science.

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