It doesn't make headlines the way cancer or cardiovascular disease do...
There are no obvious symptoms. There's no blood test to diagnose it.
And it's stealthily spreading, affecting more than half of Americans. It raises blood pressure, floods the bloodstream with stress hormones that ramp up inflammation and impair immunity, erodes cognitive health, and even shortens lives.
But despite its severity, your doctor probably hasn't asked you about it during your annual physical.
I'm talking about the epidemic of loneliness.
According to the American Psychological Association's latest Stress in America annual report, 54% of U.S. adults say they feel isolated, while half say they feel left out or lack companionship.
We live in a state of constant connectivity where you can message anyone in an instant, endlessly scroll social media, and live and work surrounded by people – yet more than half of adults feel alone.
It's more than just a social trend... In recent years, experts have declared loneliness to be a public health crisis. It's a silent epidemic.
The scary part is that loneliness can be easily missed.
It's Not 'All in Your Head'
Loneliness is more than just having the blues – it's linked to a higher risk of heart disease, stroke, dementia, depression, Type 2 diabetes, and even premature death. According to a 2023 report from the U.S. Surgeon General, loneliness is as deadly as smoking up to 15 cigarettes a day.
Suffering from chronic loneliness causes chronic stress, which drives chronic, widespread inflammation, a main driver behind a whole host of diseases.
And loneliness doesn't just hurt emotionally, but it also physically changes your brain...
A 2021 Nature Neuropsychopharmacology review of 41 studies using various brain scans and tests from 16,771 participants found that loneliness is linked to changes in brain structure and brain activity.
The researchers found abnormalities in the gray matter (brain cells) and white matter (the connections between brain cells) of the brain. These are parts of the brain that control your emotions, memory, and social thinking. They include the:
- Prefrontal cortex: the front of the brain used for decision making, planning, and controlling emotions
- Insula: another part that helps you feel emotions and understand your body's signals
- Amygdala: for processing fear and threats
- Hippocampus: key for memory
- Temporal cortex: needed for understanding social situations and other people
Researchers also observed that the brains of lonely participants responded differently from those of non-lonely participants when both groups looked at pleasant versus stressful images in social versus non-social situations.
Also, functional MRI studies found that loneliness affects various brain networks, or regions of the brain that work together. For instance, loneliness affected attention networks (for focusing on something) and visual networks (for interpreting what you see).
In other words, loneliness can warp the way you think, what you notice, and how you interpret situations.
And it gets worse... Loneliness was linked to biological markers of Alzheimer's disease, the most common form of dementia.
Older folks are at especially high risk of loneliness. They may outlive friends and family or live far away from them. Health changes can decrease mobility, increase the risk of chronic illnesses, and cause vision or hearing loss.
A recent study in the Journal of Affective Disorders found that older adults who newly experience loneliness show a fast drop in cognitive health. Researchers tracked U.K. adults aged 50 and older from a point before they ever reported feeling lonely. And once loneliness struck, these folks experienced an immediate, accelerated deterioration in memory, ability to recall names, and awareness of time (like being able to say the correct date and time).
In other words, when loneliness begins to set in, the brain starts aging more quickly.
Luckily, loneliness isn't permanent...
How to Fight Loneliness
The good news is that your cognitive health isn't doomed if loneliness strikes. The same study I just mentioned found that folks who successfully recovered from their bout with loneliness saw their rate of cognitive decline slow down. In other words, rekindling social ties doesn't just lift your mood, but it also preserves your brain health.
If you're feeling the sting of the loneliness epidemic, it's time to take action. Here are a few ways...
- Learn something new in a group. Keeping your brain active is crucial for staving off cognitive decline. Do it in a social setting and you're doubling up on the protection. Try joining a local book club, signing up for a class, or participating in a group hobby. Being surrounded by others sharing the same interests as you is a surefire way to set the foundation for new friendships.
- Try volunteering. It's another way to keep your brain active and can get you out of the house to meet new people. Plus, a 15-yearlong study published last year in the American Journal of Geriatric Psychiatry involving more than 13,000 middle-aged and older adults found that having an increased sense of purpose in life was linked to a 28% lower risk of developing dementia – even among folks with a high genetic risk of Alzheimer's. And volunteering in your community is a big way to make life feel more meaningful.
- Call someone instead of passively scrolling. Scrolling through social media isn't a substitute for a real conversation. So instead of a half hour of doomscrolling, call a friend or family member. I recommend making a call or video chatting over shooting a text. Even a short conversation and hearing your loved one's voice can lower blood pressure and trigger the release of the "love hormone" oxytocin to lower stress levels.
Once you're done reading today's issue, go ahead... Make that call.
P.S. Multiple studies have consistently shown higher rates of social isolation and loneliness among folks suffering from a health condition that's twice as common as diabetes or cancer...
That's hearing loss. And unfortunately, most of these Americans delay treatment for years – even as long as a decade – after first noticing symptoms. I covered it in my recent Retirement Millionaire issue. Or get a trial subscription to my flagship newsletter here.
What We're Reading...
- Something different: Mexico City is sinking so quickly that it can be seen from space.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
May 5, 2026