Exercise, depression and Parkinson’s
Understanding relationships with exercise, depression and Parkinson’s
As populations around the world age, so the prevalence of Parkinson’s is increasing.
There appears to be a close association between depression and Parkinson’s, and it may even be an early symptom which appears several years before the more easily recognised motor symptoms.
A large study of people diagnosed with depression found that their risk of going on to develop Parkinson’s was reduced by regular exercise.
Increasing evidence in support of physical activity
There is increasing evidence to suggest that regular physical activity can delay Parkinson’s onset, ease symptoms, and slow the progression of the condition.
As depression is common in people with Parkinson’s and often observed prior to the onset of the condition, being associated with an increased risk of developing it, the researchers wondered whether levels of physical activity had an influence on this risk.
Large-scale study in South Korea
From national health insurance records, the researchers identified 1.34 million people newly diagnosed with depression between 2010 and 2016. All were followed up to 31st December 2019, with information on their physical activity levels before and after diagnosis collected using a patient-reported questionnaire.
Patients allocated to one of four groups:
• no physical activity, either before or after diagnosis
• increased physical activity – regular exercise started after diagnosis
• decreased physical activity – people who stopped exercising following diagnosis
• continued physical activity – regular exercise before and after diagnosis
Patients who continued to exercise least likely to develop Parkinson’s
Individuals were followed up over more than five years, and during this time 8,901 of them (0.66% of the cohort) were diagnosed with Parkinson’s.
The people who carried on being physically active both before and after the diagnosis of depression had the lowest risk of Parkinson’s: about 10% lower than those who did no regular exercise.
At the other end of the spectrum, patients who stopped regular exercise after being diagnosed with depression had about a 10% higher risk compared with those who never exercised.
What might be factors at play?
The researchers found that those in the decreased activity group were more likely to have co-morbidities, such as high blood pressure or diabetes.
As the study showed that both the amount of regular exercise at the start of the study and consistency following diagnosis were important, researchers wondered whether patients who maintain physical activity may have a “motor reserve” that compensates for the motor declines that typically lead to a diagnosis of Parkinson’s, thus potentially delaying the onset of the disease.
Since depression and a decline in physical activity can themselves be early symptoms of Parkinson’s, this might partially explain why patients who stopped exercising were found to be at a higher risk. Fatigue and slight motor changes before diagnosis could also be contributing factors.
No change for those who became more active
People who started to exercise regularly only after their diagnosis of depression found no effect on their risk level, either beneficial or adverse. This could be because an “irreversible” process towards Parkinson’s was already underway in this group, according to the researchers.
They wrote:
“It is possible that there is a biological ‘tipping point’ in the development of [Parkinson’s] that render the neurodegenerative process irreversible.
“Once an individual reaches this critical point, delaying the onset of [Parkinson’s] through lifestyle changes alone may become challenging.”
Answers point the way to the need for more research
The scientists noted that a longer follow-up is needed in order to understand how the changes in physical activity are influencing the risk of developing Parkinson’s. It should also take into account the severity of a person’s depression.
Likewise, it would be useful to investigate how physical activity influences outcomes in people who are known to have risk factors for Parkinson’s and depression, such as genetic mutations, environment or family history.
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Further reading and resources
The study was published in the Journal of Psychiatric Research (external link will open in a new browser tab or window)
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