Loneliness, defined as a subjective experience of a discrepancy between the preferred interpersonal relationship an individual has and their actual interactions with others, has emerged as a pressing concern in society. Previous research has shown that between 20 and 40% of older adults in the US report feeling lonely. Additionally, research has shown that older adults who feel lonely are more prone to have a lower memory function and a faster memory decline. Memory function, particularly a decline in memory function, is one of the hallmarks of Alzheimer’s disease and related dementia. As Alzheimer’s is an incurable condition with limited treatment options available, early prevention is crucial. In research published in July 2026 in the American Journal of Epidemiology, Ryo Ikesu and colleagues investigated whether a one-time hypothetical loneliness intervention could have sustained effects on memory scores. They found that the intervention was not associated with better memory function at follow-up.
To investigate the effects of a loneliness intervention on memory function, data from the US-based Health and Retirement Study (HRS) was used. The HRS is a nationally representative study that collected data from 2006 to 2018, with approximately 20,000 participants ages 50 and older being included. Loneliness was assessed biennially through a single interview question regarding experienced loneliness over the week prior to the interview. Memory function was assessed through a composite memory score, that combined direct and proxy memory assessments. Memory function was assessed biennially through the immediate and delayed recall of a ten-word list. To assess the effect of the hypothetical intervention, a randomised controlled trial was emulated. Memory function was estimated in three scenarios: a scenario where loneliness was eliminated at baseline through the intervention, a scenario where loneliness was eliminated at each timepoint, and a scenario without a hypothetical intervention. The study found no effects of the hypothetical intervention applied either at baseline or at each timepoint on memory function over 12 years.
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The study by Ikesu and colleagues indicates that loneliness interventions might not be efficient for protecting later-life memory function and therefore have a protective effect on the risk of developing Alzheimer’s. A possible explanation for this could be that the authors tested a hypothetical intervention as opposed to an actual intervention. Additionally, there are currently no interventions that eliminate loneliness. GlobalData epidemiologists forecast that in the eight major markets (8MM: the US, France, Germany, Italy, Spain, the UK, Japan, and China), the total prevalent cases of the disease will increase from 17.4 million cases in 2026, to 22.5 million cases in 2033.
