Social isolation can lead to an increased risk of developing dementia. It relates to whether a person lives alone, and whether they see friends and family regularly or engage in social or community activities.

This is separate from loneliness – which is more to do with how someone feels about their circumstances. It’s difficult to know how much social isolation itself contributes to dementia risk as the link is complicated. Isolation might also occur as a consequence of dementia.

How does social isolation increase dementia risk?

Social isolation can increase a person’s risk of dementia by about 60%. It is not known why social isolation increases dementia risk, but one study showed how it was linked to a host of other health and social factors. Lonely people are more likely to drink heavily, smoke, not exercise and be overweight and have heart problems all of which increase dementia risk.

Social isolation is related to someone’s marital status as married people often have more social contact with others than single people. As studies show, lifelong single people are more likely to develop dementia than those who are married. Widowed people are also slightly more likely to develop dementia.

Social contact is significantly increased in married people, and there are other factors that may reduce the dementia risk for married people. Married people are more likely to be healthier and have more education.

Social contact to reduce the risk of dementia

It is thought that social contact helps with resilience against the effects of Alzheimer’s disease in the brain – known as cognitive reserve.

Engaging in social activities may help to build up your brain’s ability to cope with disease, relieve stress and improve your mood. Example of activities include:

• adult education or learning
• arts and crafts (especially in groups)
• playing a musical instrument or singing
• volunteering

It’s important to try to keep in touch with the people who matter to you, such as friends and family. Having a conversation with someone can also exercise a wide range of your mental skills, for example:

• actively listening to and communicating with the other person
• considering the meaning of what someone is trying to tell you and how they feel
• finding the right way to express what you want to say and putting words together in the right order for someone to understand
• recalling things that have happened which are relevant to what you’re talking about.

However even when accounting for these factors, social isolation is shown to increase dementia risk. There is also known to be a strong connection between high social contact later in life and memory and thinking skills.

Research into social isolation before later life

Most studies that have looked at social contact and dementia risk have followed up for less than 10 years. So we only really know about the effect of later-life social contact on dementia.

Of the few longer-term studies, one found that people who had less social contact at the age of 60, were more likely to develop dementia in the following 15 years. However, the study didn’t track their isolation throughout that period.

Another study created a 5-point scale to measure social contact:

• marital status
• family support
• contact with friends
• participation in community groups
• working

People who were positive in all these parameters were 46% less likely to develop dementia than those who scored lowest on the scale. In general, across different cultures and settings, the effect of social isolation on dementia risk remained consistent.

Can interventions to boost social contact help dementia risk?

Some research shows that people who participate in social activities are at lower risk of dementia. However most of these studies ask people about their social activities, so the cause and effect is not certain.

Research studies that test the effects of specific social activities are infrequent. One review that combined several studies suggested that participants taking part in facilitated meeting groups had better thinking skills and increased brain volume than those who did not.