Parkinson’s disease is a neurodegenerative condition that leads to progressive motor dysfunction. Though we don’t know the cause of Parkinson’s disease, both circadian disruption and physical inactivity appear to play a role.

Parkinson’s disease falls in to a category of conditions known as chronic diseases of aging. As the name suggests, risk for these diseases increases as we age, and the symptoms either persist or become progressively worse.

While there are genetic contributions to the risk of the chronic diseases of aging, lifestyle also plays a dominant role. Therefore, we can decrease our risk by adopting a healthier lifestyle. Though, it’s important to point out that genetics likely plays a bigger role in early-onset Parkinson’s disease.

A recent paper set out to determine the role circadian activity patterns play in the development of Parkinson’s disease. Results of the study found that people with the lowest amplitude of circadian activity had a 3x increased risk of developing Parkinson’s disease within 11 years.

This increased risk was independent of other circadian factors including sleep. One of the biggest misconceptions about circadian disruption is that if your sleep is fine your circadian rhythms are as well. This is not the case.

In this study, it appears that disruption in activity patterns precedes sleep problems. In fact, disrupted activity patterns may be a driver of sleep disruption later on.

Let’s take a look at the study and what it tells us about circadian rhythms and Parkinson’s disease.

Circadian disruption as a cause of Parkinson’s disease

Circadian rhythms play a dominant role in our physiology. They prepare us to dominate our environment by taking environmental time cues and optimizing our biology based on that information. Therefore, optimizing circadian rhythms is very important for optimal health. For a short rundown on circadian rhythms, check out this blog.

Circadian rhythms essentially separate functions that don’t work well together. For example, certain co-factors that are important for generating energy are also important for repairing our cells. Thus, these processes function best when separated.

There are a few environmental cues, also known as zeitgebers, that help set our circadian rhythms. Light and body temperature are the 2 most important. Feeding, and physical activity are also critically important cues for circadian rhythms.

Unfortunately, several things happen as we age that disrupt circadian rhythms. For one, changes to our eyes make it more difficult to sense blue light, the type of light we use to set our master clock. Furthermore, the clocks within each one of our cells begin to lose synchronization with one another.

This essentially leads to an impairment in our ability to develop a robust circadian rhythm. And with that, our performance declines and the housekeeping processes that mop up damage simply don’t do their job.

The 2 charts below show representative activity patterns of adults in the study. The one on the left did not develop Parkinson’s and the one on the right did. People with activity patterns similar to the one on the right had a 3-fold increase in Parkinson’s risk compared to the left.

What’s interesting about the study is that it didn’t matter so much when activity was performed. The amplitude mattered. In other words, how much activity was performed throughout the day.

How physical activity helps circadian rhythms

The likely driver of this increased risk is related to activity and body temperature. Physical activity increases core body temperature, which itself is a major synchronization cue.

Due to the changes mentioned above, light becomes less effective of a synchronization cue as we age. Though the master clock helps regulate circadian variation in core body temperature, other factors do as well.

Daily physical activity and feeding patterns increase core body temperature independently of the master clock. And core body temperature is a MAJOR zeitgeber that synchronizes all cells in a tissue and all peripheral clocks to one another.

With light being less effective, core body temperature is a highly effective back up that can keep your clocks ticking on time. Unfortunately, if you’re sedentary, the increase in body temperature during the day may not be enough to function as an effective zeitgeber.

As a result, your cells and organs simply cannot tell time. Unfortunately, the abnormal proteins that accumulate in Parkinson’s disease eventually make their way in to the master clock. At this point, it may be too late to intervene.

Thus, maintaining circadian activity patterns is important to keep your clocks ticking on time.

Conclusion

Circadian rhythms play in an important role in keeping us healthy and lowering the risk for age-related disease. As we age, the clocks in our cells don’t keep time as well as they did when we were young. As a result, our behavior plays a bigger role in helping keep time.

In Parkinson’s disease, disruption of activity patterns precedes both sleep disruption and motor dysfunction. This indicates that disrupted activity patterns may be a cause of Parkinson’s disease.

Evidence suggests that exercise is highly beneficial for managing or delaying the symptoms of Parkinson’s disease. Be that as it may, exercise is generally short in duration.

This paper suggests that being physically active throughout the day may provide additional benefit by enhancing the robustness of circadian rhythms.