Mental Effects of Loneliness

Loneliness is something we all deal with from time to time but humans are built as social creatures, which is why chronic loneliness has both physical and mental effects. In 2023, the then US Surgeon General, Dr. Vivek Murthy, declared loneliness an epidemic. In 2020, a report confirmed that nearly 61% of Americans said they were lonely. This number has only been shown to increase after COVID-19. The effects of this specific epidemic are twofold: mental and physical effects. In this article I will focus on the mental effects but know that the physical effects are just as strong.

Humans have always been social creatures; we evolved to be social because it helped our ancient ancestors. When humans had to hunt and when we weren’t equipped with the technologies we have today, humans were not at the top of the food chain. This meant humans who were loners tended to die off and humans who were social and traveled in groups were better suited for survival. This is how we humans evolved to be social creatures and now when we disregard that part of ourselves, it can be physically and mentally detrimental to us.  

The first thing you need to know is that loneliness is not the same as solitude, despite the two commonly being used interchangeably.  Loneliness refers to an unwanted feeling of isolation and it can cause depression. On the other hand, solitude refers to a state of being alone which is usually chosen and enjoyed for a short time. 

Focusing on the mental effects, loneliness and chronic loneliness have slightly different effects. Both are associated with increased risks of depression and anxiety. Studies have shown that chronic loneliness can lead to elevated stress hormones which, if you look at my article, “The Effects of Stress On Your Body”, you will see that it can greatly impact your entire body and nearly every system. Chronic loneliness can also lead to visible deterioration of a person’s brain, particularly in places that control emotions and social interactions. These specific changes can lead to a person becoming more sensitive to social threats, more likely to interpret social cues in a negative way. Eventually these effects lead to the person intentionally avoiding social interactions, forcing them into a perpetual cycle of chronic loneliness. 

Chronic loneliness also leads to mental effects that aren’t just emotional or psychological. It can also affect a person's cognitive health. Many studies including Guarnera et al., 2023, show a distinct connection between loneliness and dementia. Other studies show that loneliness could increase the risk for Alzheimer’s Disease by 14%, vascular dementia by 17%, and cognitive impairment by 12%. These are all very real effects of loneliness, effects that impact thousands of people daily. 

Not only does loneliness affect social engagement but also cognitive engagement. Loneliness can lead to a heavy disinterest in activities, such as learning new skills or topics,  that stimulate a person's cognitive thinking brain areas. This can further accelerate cognitive decline. Lammer et al., 2023 showed that loneliness has a connection with a reduction in grey matter within specific brain areas such as the hippocampus which is associated with memory, learning, and navigation. Grey matter is one of the two most basic brain divisions: white and grey matter. Grey matter is especially important for information processing,  controlling muscle movement, and regulating sensory perception. It helps in the most basic functions of life and that is why it is easy to understand how detrimental any damage to it could be. 

According to Dr. Vivek Murthy, the mortality rate of loneliness is nearly the same as smoking 15 cigarettes a day. It is not just a feeling that can easily be wiped away, but a real condition that takes time and effort to combat. 

Citations:

1. Guarnera, J., Yuen, E., & Macpherson, H. (2023). The Impact of Loneliness and Social Isolation on Cognitive Aging: A Narrative Review. Journal of Alzheimer's disease reports, 7(1), 699–714. https://doi.org/10.3233/ADR-230011 

2. Novotney, A. (2020, March 24). The risks of social isolation. Monitor on Psychology, 50(5). https://www.apa.org/monitor/2019/05/ce-corner-isolation 

3. U.S. Department of Health and Human Services, Office of the Surgeon General. Our Epidemic of Loneliness and Isolation: The U.S. Surgeon General’s Advisory on the Healing Effects of Social Connection and Community. May 2023, https://www.hhs.gov/sites/default/files/surgeon-general-social-connection-advisory.pdf. 

4. Godard, Mackenzie. "What Loneliness Does to the Brain: Effects on Cognitive &
     Mental Health." Creyos, 12 May 2025, creyos.com/blog/social-isolation
     Accessed 11 Aug. 2025.

5. "Signs and Symptoms of Chronic Loneliness." Cigna Healthcare, www.cigna.com/knowledge-center/chronic-loneliness. Accessed 11 Aug. 2025.

6. Thomas, Bella Isaacs. "Disconnected: What's Happening in the Lonely Brain."
Brain Facts, 19 Sept. 2024, www.brainfacts.org/diseases-and-disorders/mental-health/2024/disconnected-whats-happening-in-the-lonely-brain-091924.
     Accessed 11 Aug. 2025.