The short answer
- Isolation raises the risk, it does not decide itResearchers count it as one of several measurable risk factors for dementia. None of them, on its own, makes dementia certain or rules it out.
- It seems to work through more than one routeFewer conversations mean less everyday exercise for memory and language, and isolation also makes low mood and unhealthy habits more likely, each a risk in its own right.
- Loneliness does not always look like lonelinessA parent who insists they are fine can still have gone weeks with barely a real conversation. There are quieter signs to watch for.
- Regular company is something you can arrange this weekFamily visits, a local group, or a companionship carer from £15 an hour with our fee included all count, as long as they happen often enough to be routine.
Figures for carers on PrimeCarers include our fee, £15 to £20 an hour. Health figures are from Alzheimer's Society and the 2024 Lancet Commission on dementia prevention, checked September 2026.
The evidence
How much social isolation raises the risk
Two different kinds of figure get used when this question comes up, and it helps to keep them apart: how much extra risk one isolated person carries, and how much of all dementia, across a whole population, traces back to isolation rather than the many other things that raise the risk.
60%
higher risk of dementia for someone who is socially isolated
The estimate Alzheimer’s Society uses from the studies it has reviewed. Individual studies vary a good deal, some finding a smaller rise, because isolation is hard to measure consistently and long follow-up studies are still rare.
Alzheimer’s Society, "Social isolation and dementia risk"
5 in 100
dementia cases worldwide linked to social isolation in later life
Social isolation is one of 14 factors across a lifetime that the Commission judges modifiable. Together, all 14 account for around 45 of every 100 cases.
The Lancet Commission on dementia prevention, intervention and care, 2024
Both figures point the same way, even though they measure different things. Somebody who has gone from a full diary to very little company most weeks has picked up a risk factor worth taking seriously, in the same category as high blood pressure or not moving about enough. It does not make dementia likely for that person, and it is not proof that isolation causes it rather than being an early sign of it: some of the people counted as isolated in these studies may already have been withdrawing because memory problems were starting, which is one reason the estimates vary. What it does mean is that company is one of the few parts of the picture a family can change this week, rather than one to wait on a GP appointment for. Companionship care is built around exactly that, regular time with somebody who keeps a conversation going.
Why it matters
Why isolation seems to affect the brain, not only the mood
Alzheimer's Research UK sets out three routes that, together, explain why researchers take this risk factor seriously rather than treating it as a side effect of getting older.
Less everyday exercise for the brain
Conversation
Fewer reasons to look after yourself
Daily habits
A higher chance of low mood
Depression
None of these three routes needs to be dramatic to matter. A quiet week with almost no conversation, repeated often enough, is what the research is describing, not a single bad month. If your relative already has a diagnosis and you want to understand what happens from here, dementia care covers the wider picture.
Spotting it
Signs your relative is isolated, not just enjoying the quiet
Isolation is often invisible from the outside, especially over the phone, and even a proud parent who says they are fine can be having far fewer real conversations than they used to.
Worth noticing on your next visit or call
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What to look and listen for
What they might say
How do you help an elderly person who is lonely? covers how to raise it without the conversation feeling like a checklist.
What helps
What tends to help, and what a companionship carer adds
Once you have noticed the signs, the answer is rarely complicated. It is more company, of a kind your relative will keep saying yes to, rather than a single big occasion a few times a year.
What tends to work
- Something regular on the calendar, even once a week, rather than a one-off outing
- A person or a group they already have something in common with
- A short visit they can manage easily, rather than a big day out that leaves them worn out
- The same face turning up, so a relationship builds rather than starting over each time
- A local group through the library, a place of worship or Age UK, alongside family visits
What tends not to
- Waiting for a quieter week to arrange it, which tends to mean it never happens
- One big family occasion a few times a year, with little in between
- Assuming a phone call does the same job as somebody sitting in the room
- A different face every visit, which asks a lonely person to make a new friend each time
- Leaving it to one family member, who then can never take a week off
A companionship carer is one way to make the regular part of this reliable, rather than something that depends on everyone's diary lining up. Visits are booked directly with a self-employed carer near your relative, from £15 to £20 an hour with our fee included, against £28 to £35 an hour through a typical agency for the same visit. Every carer has an online interview and has their identity, right to work and an enhanced DBS check completed before they appear on the site. Activities carers do with clients covers what fills a visit, can carers take you out? covers outings specifically, and how much does a companion carer cost? has the fuller figures. Age UK's guide to loneliness is a good next stop for local befriending services alongside a paid carer.
Questions
Questions families ask about isolation and dementia risk
Both are possible, and researchers cannot always tell them apart. Isolation for years beforehand is linked to a higher risk, but withdrawing from other people can also be one of the first signs that memory and thinking have already started to change. This is one reason the studies behind these figures do not prove that isolation alone causes dementia.
Alzheimer’s Society puts it at around 60% higher risk for somebody who is socially isolated, drawing on the studies it has reviewed, though individual studies vary a good deal. Across the whole population, the 2024 Lancet Commission on dementia prevention links about 5 in every 100 dementia cases worldwide to social isolation in later life specifically.
No. Social isolation is one of 14 factors across a lifetime that the Lancet Commission judges modifiable, and together all 14 account for around 45 of every 100 dementia cases. Addressing all of them, not isolation on its own, is what that figure describes, and dementia can still develop in somebody with an active social life.
Start smaller than a group or an outing. A regular visitor who comes to them, whether family, a befriending volunteer or a companionship carer, often works where an invitation to a club does not. How do you help an elderly person who is lonely? covers how to raise it gently.
Yes. The routes researchers describe, conversation, routine and company, do not depend on who is providing them. A carer who visits at the same time each week gives a familiar face and a proper conversation, which is what the evidence points to as helpful, alongside family contact rather than instead of it.
There is not strong evidence either way, and a call is far better than nothing. Where you can manage it, an in-person visit gives more of the everyday mental exercise, the shared activity and the reason to get up and dressed that seem to matter most, so it is worth keeping visits in person where distance and time allow it.