September 27, 2025

Loneliness Might Be as Dangerous as Smoking

It may sound like a sensationalized headline, but it isn’t. There is growing scientific evidence suggesting that social isolation and loneliness are emerging as major public health concerns – possibly rivaling smoking.

This is a big deal for a few reasons. First, humans are fundamentally connected beings. Second, when our social connections decline — whether due to divorce, loss of a spouse, moving away, etc. — our health declines as well.

TED Talks Put Lonliness On The map

Harvard psychologist Robert Waldinger, who heads up the Harvard Study of Adult Development (one of the longest running longitudinal studies of adult development), discussed this topic in a popular TED Talk in 2015. Since 1938, over 700 men have participated in this study and their progress has been followed from adolescence into old age.

At the end of the study, Waldinger came to a very straightforward, yet somewhat surprising conclusion. Good relationships lead to better health and happiness. The study showed that relationship quality at age 50 was a far stronger predictor of overall health in old age than virtually every other known health-related factor. And conversely, feelings of loneliness and social isolation can shorten one's life.

Distinguishing Between Social Isolation & Loneliness

A recent 2023 meta-analysis of multiple studies distinguished between two separate, though interrelated constructs:

Social isolation is objective. It is based on the number of social connections you have.
Loneliness is subjective. It is the feeling of being alone, regardless of the number of people around you.

While you could be socially isolated without feeling lonely; you can also feel lonely, despite having a busy and social life.

Both Concepts Linked to Higher Risk of Death From All Causes

According to the same 2023 meta-analysis, both loneliness and social isolation were linked to increased risk of death from all causes. Specifically:

Loneliness was associated with a 14% increase in all-cause mortality.
Social isolation was associated with a 32% increase in all-cause mortality.
Social isolation was also linked to:
24% increased risk of cancer mortality.
34% increased risk of death from heart disease.

Recent research has also identified strong links between loneliness and poor brain health outcomes.

Specifically:

A 31% increased risk of dementia.
Nearly 40% increased risk of developing Alzheimer’s disease.
Shorter telomere lengths (a marker associated with cellular aging).

Cardiovascular risk factors (such as high blood pressure) have also been shown to impact the risk of developing dementia. Read more on blood pressure and dementia.

Are the Associations Between Social Isolation/Loneliness and Poor Health Likely Causal?

Due to ethical considerations, all studies assessing the association between social isolation/loneliness and poor health outcomes are observational. Therefore, while these studies provide compelling associations, they do not establish direct causality.

However, given the sheer size and consistency of the body of evidence, many researchers believe that the associations are likely causal.

Increasing Rates of Loneliness

Survey data indicate that rates of loneliness and social isolation are on the rise. Specifically, among older adults in the U.S.:

Over one-third of Americans aged 50-80 report feeling a lack of companionship sometimes or often.
Approximately 29% of Americans aged 50-80 report feeling isolated sometimes or often.
Another survey found that nearly 43% of adults reported feeling isolated, and approximately 39% of respondents reported not feeling close to anyone.

Similar trends appear to be occurring globally, and in some cases, are becoming more pronounced.

Why this is happening

Smartphones and screen time are a common reason why we are spending too much time in front of screens. We spend about 6 hours and 40 minutes per day using our phones and tablets. The trend of increased screen use has been around longer than social media. Since the 1960s, we have seen a decline in community participation, according to Robert Putnam's 2000 book "Bowling Alone". There are many factors that have led to these declines including:

Increased TV and media viewing
Less walkable communities
Shift in American culture toward individualism
Decrease in number of children
Increase in people living alone

Many assume that being socially active on line will help to combat loneliness. However research indicates that the opposite is true. Increased social media use has shown to increase feelings of loneliness as well as poor mental health outcomes.

How to Really Help People

Meta-analyses of loneliness intervention studies identified several consistent findings:

Long-term lifestyle changes are better than short-term programs.
Group based programs are better than working individually with a person.
Face-to-face (in-person) contact is better than online communication.
Increased frequency of contact results in better outcomes.

Building connections is not something that happens once, it takes commitment to make a part of your lifestyle.

Ways to Build Regular Connection

Regularly engage in in-person activity and incorporate your social network.

Find ways to add a social element to your exercise. Take a group fitness class, join a running club or train with a friend. Even small amounts of exercise can show positive impacts on health.
Create social time out of your daily routine. Meet friends at a local café or get together with fellow parents while engaging in a family-friendly activity.
Get involved in a book club. Choose a book every month and attend a meeting with other club members to talk about the book.
Get involved in volunteering. Organizations in your community create opportunities for connections.

Conclusion

Health is not just diet, exercise and sleep. Social connection should also be included.

Isolation is not just mentally damaging. It can also be physiologically harmful.

To protect your long term health, develop healthy relationships as a core habit.

Research Sources

Filed in: Lifestyle

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