Loneliness May Increase Parkinson’s Disease Risk

People who experience loneliness may be at a significantly higher risk of developing Parkinson’s disease, according to a new study.

In 2023, the U.S. surgeon general released an advisory on "the epidemic of loneliness" associated with a higher risk of cardiovascular disease, dementia, stroke, and premature death.

A new study published in JAMA Network indicates that people who experience loneliness may also be at a 37% higher risk of developing Parkinson’s disease (PD), a neurodegenerative disorder affecting nearly one million Americans.

Researchers at Florida State University looked at data from 491,603 participants from the U.K. Biobank database. They were 56.54 years on average and did not have a Parkinson’s disease diagnosis at the beginning of the study.

Nearly one in five (18.5%) participants said they often felt lonely. Those reporting loneliness were slightly younger, were more likely to be female, and had fewer resources, such as a college degree. They also tended to engage in more health risks, including smoking and physical inactivity, and had worse mental health.

During a 15-year follow-up, 2,822 of the participants developed Parkinson’s disease. Those diagnosed with PD were older, were more likely to be male, had a higher body mass index (BMI), and were more likely to have chronic conditions.

The link between Parkinson's and loneliness may be underestimated

The study does not prove that loneliness causes Parkinson’s disease; it just shows an association.

The authors hypothesize that the association could be due to shared risk factors of these conditions, such as genetics or mental health conditions. Another possible explanation is that loneliness increases during the early phase of Parkinson’s disease, in which motor symptoms haven’t appeared yet, but depression, fatigue, anxiety, or apathy are common.

Most probably, however, loneliness increases the risk of Parkinson’s disease through metabolic, inflammatory, and neuroendocrine pathways, the authors note.

The study also has limitations. As loneliness was assessed by a single "yes" or "no" item, the association between loneliness and PD could have been underestimated. Moreover, the use of hospital admission and death records could have resulted in missing PD diagnoses at the early stages.

What are Parkinson’s disease symptoms?

Parkinson’s disease usually develops slowly over years, and its progression may be different from one person to another.

The symptoms of PD may include:

• Tremor, mainly at rest and in hands, characterized by simultaneous rubbing movements of thumb and index fingers against each other. Other forms of tremor are possible.
• Slowness and paucity of movement.
• Limb stiffness.
• Gait and balance problems.

Scientists still don’t know what exactly causes Parkinson’s disease, but they believe the condition develops due to a combination of genetic and environmental factors.

While the new study does not prove a solid connection between feeling lonely and Parkinson’s disease, it adds evidence on the detrimental health impact of loneliness.