Loneliness is increasing in the UK. The Office for National Statistics reports that across Great Britain 8% of adults state they feel lonely often or always. Alongside concerns about the negative effects on society, there has been an increasing interest in the links between loneliness and health. The WHO Commission on Social Connection and the US Surgeon General have both publicly called for loneliness to be treated as a public health priority.

We wanted to examine the links between loneliness and health to better understand whether loneliness and social isolation actually cause worse health. If we know more about the relationship between loneliness and health, we can better assess if interventions to tackle loneliness would lead to improved health outcomes.

In collaboration with the University of Bristol, Amsterdam University Medical Centre and other academic partners, we conducted new analyses to investigate the relationship between loneliness, social isolation and health. We took a broad definition of health, looking at measures of physical, general and mental health, as well as wellbeing.

We conducted three types of analysis to assess whether loneliness and/or social isolation may cause various poor health outcomes. We say there is good evidence of causality when we find an effect across all three types of analysis and when the sensitivity analysis also supports the presence of a causal effect. You can find more information in the report and technical appendix.

• There is good evidence that loneliness causes worse mental health and wellbeing outcomes. The impact on mental health is potentially substantial, for example, people who report feeling lonely are 2.25 times more likely to have been diagnosed with depression compared to those who don’t report feeling lonely.
• There is good evidence that social isolation causes lower levels of happiness and meaning in life, two of our wellbeing outcomes. Social isolation was associated with mental health but it was not clear if this relationship was causal.
• The evidence was mixed for whether loneliness causes worse general health outcomes. We didn't find evidence that social isolation causes worse general health outcomes.
• We didn't find evidence that loneliness or social isolation causes worse physical health outcomes.

Tackling loneliness may be an effective strategy to improve mental health and wellbeing, given the evidence of a causal relationship. With the current challenges facing the delivery of mental health services, we recommend exploring the cost-effectiveness of interventions to reduce loneliness and isolation, compared to other types of mental health support.

We did not find that loneliness causes worse physical or general health outcomes. We recommend including health outcomes in future studies of loneliness/social isolation interventions would help to build evidence on whether loneliness and/or social isolation leads to poorer health. We recommend this across all health measures, but especially for physical and general health outcomes where the evidence is weaker.

This report closes Nesta’s current work on loneliness, social isolation and health. We look forward to seeing future developments in the sector.