Loneliness: Health Risks and Strategies — A Conversation with Professor Riedel-Heller (Part 2)

In the first part of our conversation with Professor Riedel-Heller, we discussed what loneliness is and how it manifests across age groups. We now turn to health and prevention.

When we speak about loneliness, it is, on the one hand, a feeling — an impairment of well-being — and, on the other, a medical risk. The first is intuitive; how does the second arise?

Loneliness carries consequences for health, for disease, and even for mortality. That is not new. As early as 2015, an influential meta-analysis by a U.S. colleague showed that loneliness is associated with a 26% increase in mortality. Numerous studies followed, along with meta-analyses focusing on specific conditions, studies that synthesize many individual studies.

These show that loneliness is linked to both mental and physical disorders. It more than doubles the risk of later developing depression, and the pattern is similar for anxiety disorders. Loneliness is also associated with physical diseases: cardiovascular disease, diabetes, cognitive impairment, and dementia. It increases the risk of dementia by 26%.

How, then, does loneliness get “under the skin”? Put simply, loneliness triggers a chronic stress response. We are social beings. This response is mediated by persistently elevated cortisol, a stress hormone that downstream promotes inflammation. Chronic stress is also known to foster unhealthy behaviors — smoking and poor diet: a cigarette here, a quick fast-food meal there.

Would that include increased alcohol consumption?

Yes. Alcohol is used to reduce stress and has adverse effects.

Loneliness and depression are often discussed together. Are people with depression more likely to be lonely, or do lonely people more often become depressed?

Both statements are accurate. Depressed individuals experience low mood and reduced drive, and often lack the energy to engage socially. During an episode of illness, people with depression are frequently lonely. A very recent review indicates that nearly 60% of people with severe mental disorders are lonely.

Research also shows that people who are lonely face a higher risk of developing depression later on. Longitudinal studies — often spanning many years — clarify the sequence: first loneliness, then the subsequent onset of depression.

People often say, “You’re lonely — get a dog.” The “pet against loneliness” idea is popular. Would I then be less lonely, or lonely with a dog?

That is a good question. I suspect there are as many possibilities as there are people and dogs. Research does include a number of studies showing that pets reduce loneliness, but not all studies find this effect. A 2022 review by André Hajek’s group in Hamburg summarizes the evidence well.

You also end up meeting people.

You do indeed meet others, especially fellow dog owners. Conversations often arise naturally. Still, I would not claim that a dog is a cure-all for loneliness.

Strategies to counter loneliness cover a wide spectrum. In older adults, the transition to retirement, along with the loss of workplace contacts, possible health limitations, and the potential loss of a partner, can set the stage for isolation. How can individuals, or their relatives, respond?

It is true that, at retirement, many people lose social contacts. Even colleagues one did not much like can be missed a bit. If, later in life, the loss of a partner or friends occurs, these are real challenges. Many interventions against loneliness have been studied.

Broadly, they fall into three strategies: (1) increasing opportunities for social contact; (2) building skills to engage more effectively — such as social-skills training; and (3) training in social cognition, that is, developing the ability to understand others’ emotions, thoughts, and intentions and to respond appropriately. But you are asking for everyday tips?

Can we meaningfully offer tips? My question is: How can we recognize when someone is slowly, almost imperceptibly, becoming isolated? At first, it may be limited contact, and then, suddenly, a moment arrives when the person begins to reject contact. How do we recognize that, and what can we do? Once contact is rejected, it is difficult.

It is important to sensitize people to the importance of social ties. Good relationships are rarely self-sustaining. In Germany we sometimes refer to a “social home medicine cabinet.” That includes two, three, or four very good contacts that one actively maintains. You have to stick with it before the damage is done. In school — through classes or sports teams — much happens spontaneously.

As we age, far less occurs on its own. It is crucial to realize that we must take deliberate care. It is not about surrounding oneself with twenty people, but about two, three, or four close ties – people with whom one can exchange meaningfully and with whom one maintains regular contact: weekly calls, occasional meetings, a consistent cadence.

When we think in terms of tips, we often focus on what the individual can do. But there is a higher level as well, where neighborhoods, municipalities, and society come into play. Are there places, cafés, or public transport that enable people to come together?

Since 2023 there has been a Federal Government Strategy against Loneliness. What can — and should — policy, particularly local government, do?

England even has a Minister for Loneliness. The WHO recently published “From Loneliness to Social Connection,” which presents the issues clearly. The Federal Government Strategy against Loneliness shows an understanding that, beyond individual factors, neighborhoods, municipalities, and society exert influence. That is appropriate, because much can be set in motion there. This extends to urban planning: How are residential areas designed? Are there places to meet, or only residential silos?

What can local government do, specifically?

Anything that fosters social integration. The range is broad: e.g. culture, sports, senior centers and the support of clubs. These are places where people come together — the full breadth of civic engagement. Municipalities therefore carry significant responsibility. Naturally, that includes adequate offerings for children and adolescents.

Those were my questions. Would you like to add anything?

Two points. First, this year the Harvard Business Review published a piece examining what people use AI for. Topping the list in 2024 was “generating ideas”; in 2025 it was “therapy and companionship.” I found it very interesting — and somewhat irritating — that more and more people are turning to AI for emotional support, grief work, and self-reflection. A current study from the tech field, available so far only as a preliminary version, a preprint, found that higher daily use was associated with greater loneliness, dependency problems, and reduced social interaction. We will certainly learn much more about this.

Second, loneliness is en vogue in science — one might call it a hype. The topic resonates with research funders; everyone understands it. Overall, I would like to few research on loneliness and its consequences within a broader context: research on the social determinants of health and disease – those conditions into which people are born and in which they grow up, live, work, and age. This has long been a central field of research. It is good that we are talking more about it now.

Professor Riedel-Heller, let us make that the closing word. Thank you for the conversation.