Social connection and ageing: what studies show

Loneliness and social isolation: what do the words mean?

The WHO Commission on Social Connection separates three ideas. Social connection is the ways people relate to and interact with others. Loneliness is the painful feeling that arises from a gap between desired and actual social connections. Social isolation is the objective lack of sufficient social connections. It follows that a person can be surrounded by others and still feel lonely, or see few people without suffering from it.

What did the Holt-Lunstad meta-analysis find?

In 2010, Julianne Holt-Lunstad, Timothy Smith and Bradley Layton pooled 148 studies covering 308,849 participants, followed for 7.5 years on average (from 3 months to 58 years depending on the study). People with stronger social relationships had a higher likelihood of survival over the follow-up period: the average odds ratio was 1.50 (95% confidence interval 1.42 to 1.59), which the authors describe as a 50% increased likelihood of survival.

The authors consider the size of this association comparable with well-established risk factors such as smoking. With the most complete measures of social integration, the gap was larger still: the odds of survival were 91% higher.

How to read an odds ratio

The Holt-Lunstad meta-analysis reports its main result as an odds ratio of 1.50, with a 95% confidence interval of 1.42 to 1.59. An odds ratio compares the odds of an outcome in two groups: a value of 1 means no difference, and a value above 1 means higher odds in the group with stronger relationships. The authors describe 1.50 as a 50% increased likelihood of survival. The confidence interval tells you how precisely the average was estimated; it does not tell you what will happen to any one person.

The pattern across measures is informative. The association was strongest for complex measures of social integration (odds ratio 1.91) and lowest for the simple question of whether someone lives alone or with others (1.19, with an interval that includes 1). In other words, how people are connected seems to matter more in these studies than whether they share a home.¹

What did the WHO say in 2025?

On 30 June 2025, the WHO released the global report of its Commission on Social Connection. It estimates that one in six people worldwide feels lonely and links loneliness to an estimated 100 deaths every hour, more than 871,000 a year. Young people are affected too: 17% to 21% of those aged 13 to 29 report feeling lonely, with the highest rates among teenagers. Reported loneliness is more common in low-income countries (about 24%) than in high-income countries (about 11%). Data on social isolation are more limited: it may affect up to one in three older adults and one in four adolescents.

A second meta-analysis: isolation, loneliness and living alone

In 2015, Holt-Lunstad and colleagues returned to the question with a different set of studies. Their review looked at social isolation, loneliness and living alone, using studies published between 1980 and February 2014, and found similar-sized associations with early death.³

The abstract adds three nuances. The authors found no difference between objective and subjective measures of isolation. The results were consistent across gender, length of follow-up and world region. And social deficits were more predictive of death in samples with an average age younger than 65, so the association is not simply a feature of old age.³ As with the 2010 review, these are associations: they do not show that changing someone's social life would change the outcome.

What this research cannot tell you

• It does not prove that social ties cause the gap observed: people cannot be randomly assigned to social situations, as Holt-Lunstad and colleagues point out.
• Most measures did not take the quality of relationships into account: a strained relationship counted like any other.
• The data come mostly from North America and Western Europe, and only English-language papers were coded.
• The figure of 871,000 deaths a year is a WHO estimate, not a count.
• None of these sources sets an ideal number of friends or social contacts.

Keeping in touch day to day

The sources read describe associations and offer no recipe. Some simple pointers remain, based on common sense rather than on a study result: keep a regular date with someone close to you, join a group activity near where you live, offer to help. To make a regular date stick, the simplest approach is often to tie it to a stable cue in your week, as research on how long it takes to form a habit suggests.

Using this research in daily life

Because the sources read describe associations, the useful way to use them is as a reason to take social contact seriously, not as a prescription. Two of the habits that research on routines supports apply here: choose something small, such as a weekly call, and tie it to a cue that already exists in your week. A walk with a neighbour combines contact with movement, as described in walking and longevity. For the national figures that put these questions in context, see healthy life expectancy, and for what research does and does not show about long-lived communities, read Blue Zones. The whole topic is gathered in healthy ageing research.

For the situation in the United Kingdom, see loneliness in older people in the UK.

When to ask for help

If a feeling of loneliness lasts or weighs on your mood, talk to your GP. Local councils and charities that work against isolation can also point you to activities or visits. If you are having thoughts of suicide, call Samaritans free on 116 123, day or night. This page summarises research and does not replace medical advice.

Frequently asked questions