Men who were both lonely and isolated lost 5.8 years free of depression and anxiety

Among 277,489 middle-aged and older adults followed for roughly 13 years, the men whose lives were marked by both loneliness and social isolation could expect to spend far less of their lives free of mental illness than peers who were neither. The estimated gap for men was about 5.8 years. For women in the same position it was smaller on the mental side, and it came with a physical cost as well.

The analysis was led by Lu Qi, the HCA Regents Distinguished Chair and a professor at Tulane University’s Celia Scott Weatherhead School of Public and Tropical Medicine. Qi’s team worked with data from a very large British cohort and asked a question that most loneliness research skips: not only whether people with weak social ties get sick more often, but how many healthy years the pattern removes from a life.

The 5.8-year gap and how the study counted it

The finding, published in Nature Communications, is that at age 50, men who were both lonely and socially isolated lived about 5.8 fewer years free of mental disorder than men who were neither, with depression and anxiety among the conditions tracked. The comparison is a projection of disease-free life expectancy from age 50, not a count of years that individual men actually lost.

All 277,489 participants were between 40 and 69 and, at the start, had none of seven major conditions: type 2 diabetes, cardiovascular disease, chronic respiratory disease, neurodegenerative disease, cancer, depression and anxiety, according to the UK Biobank record of the paper. Follow-up for the disease outcomes had a median of 13.4 years and ended on December 31, 2022. Because the researchers separated physical disease from mental disorder, the results show where the damage concentrates. Loneliness and isolation were more strongly tied to years free of mental disorder than to years free of physical disease, for both sexes, which means the burden of weak social ties falls mostly on mood and anxiety rather than on the heart, lungs or cancer risk, at least within this cohort and this follow-up window.

Loneliness and isolation are measured separately

The two terms are often used interchangeably, and the study did not. Social isolation is the objective side: how few connections a person has. Loneliness is the subjective side: dissatisfaction with the quality of relationships, regardless of how many interactions fill a week. In the paper, loneliness was scored from two self-reported items, whether a person often feels lonely and how often they can confide in someone close, and a score of 2 on that 0-to-2 scale counted as lonely.

Isolation drew on three items: living alone, seeing friends or family less than monthly, and not joining a social or leisure activity at least weekly. A score of 2 or more out of 3 counted as isolated. Those are brief measures, and the authors acknowledge it, along with a single baseline assessment and self-reported lifestyle data. They also note that UK Biobank volunteers are not a random sample of the population, with a response rate of just 5.5 percent.

Men lost more mental health years, women lost more physical ones

According to the Tulane release carried by ScienceDaily, women who experienced both loneliness and isolation lost about 2.4 years free of physical disease and 3.7 years free of mental illness. Men lost about 1.7 years of physical disease-free life and the 5.8 years on the mental side. The mental toll was the larger one for both sexes, but the male figure was the largest in the study by a clear margin.

Qi offered a partial explanation. Qi said the research found that “men are more susceptible to being affected by loneliness,” adding that the sex difference also reflects women generally living longer and having advantages against certain diseases, as News-Medical reported. The explanation is a hypothesis about the pattern, not something the data prove, and the release itself says the team intends to test causality in other populations and in clinical trials. Qi summarized the overall result this way: “Overall, the study found that social isolation and loneliness can have a significant impact on disease-free life expectancy.”

Healthy habits blunted isolation but not loneliness

The lifestyle analysis may be the most practically interesting part. The researchers built a five-point score from smoking, body mass index, physical activity, diet and sleep. Among isolated people, healthier scores were associated with a smaller loss of disease-free years. In the paper’s example, women’s mental-disorder loss tied to isolation was 2.2 years in the unhealthy-lifestyle group, 1.1 in the medium group and 0.6 in the healthy group, where the difference was no longer statistically significant.

Loneliness behaved differently. Its association with lost years did not shrink significantly as lifestyle improved, and for women the mental-disorder loss was 3.1, 2.6 and 4.2 years across the unhealthy, medium and healthy groups, with no steady decline. Neuroscience News described the same split: exercise, diet, sleep and not smoking helped offset the objective problem of having few contacts, but not the felt sense of being alone. The authors suggest the two conditions may need different interventions.

The study is observational, so it shows association rather than cause. People who are already prone to depression may withdraw from others, and the brief questionnaire items cannot separate that possibility from the reverse. Even so, the size of the estimated gap and the contrast in how lifestyle affected the two exposures give clinicians and public health planners a concrete reason to treat felt loneliness as its own target, separate from simply getting people out of the house.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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