The Effect of Diet on Prodromal Features of Parkinson Disease

It has been well established that diet affects the brain in many ways. A new investigation1 into healthy diet patterns and their effect on prodromal features of Parkinson disease adds to the current body of literature.

Lead author Samantha A. Molsberry, PhD, who is a postdoctoral research fellow in the Department of Nutrition at the Harvard T.H. Chan School of Public Health in Cambridge, Massachusetts answered questions about the study results.

Consultant360: For your study, you and your team aimed to assess the relationship between diet pattern and prodromal features of Parkinson disease. What prompted you to conduct this assessment?

Samantha A. Molsberry, PhD: Because there are no current treatments to slow or prevent progression of Parkinson disease after diagnosis, there has been a push in recent years to better understand and characterize the prodromal phase of Parkinson disease, during which the disease is developing but has not yet reached clinically diagnosable levels.

We have an ongoing investigation on a number of symptoms that commonly occur during this prodromal period. Based on previous analyses on diet and risk of Parkinson disease in our cohorts and results coming out from other investigators, we thought it would be interesting to see whether we observed similar results for the relationship between diet and these prodromal features.

C360: Your analysis included 47,679 participants from the Nurses’ Health Study and the Health Professionals Follow-up Study. Prodromal features of Parkinson disease, including constipation and rapid eye movement sleep (REM) disorder, were assessed via the 2012 survey, and additional features were included in the 2014-2015 survey. Can you talk more about the prodromal features and which ones were most affected by diet?

Dr Molsberry: Research over the last couple of decades has established that Parkinson disease likely has a long prodromal period. During this time, patients often report a variety of motor and nonmotor symptoms. In our study, we assessed 2 common prodromal symptoms, probable REM sleep behavior disorder and constipation, in all 47,679 participants included in this study.

Additionally, in a subset of 17,400 participants, we measured 5 additional prodromal symptoms: poor color vision, depressive symptoms, body pain, hyposmia, and excessive daytime sleepiness. In our study, we found that having the co-occurrence of 3 or more of these symptoms was strongly associated with diet. Additionally, we found that constipation, excessive daytime sleepiness, and depression were individually associated with diet.

C360: Your team also assessed the potential long-term effects of diet on Parkinson disease features. What long-term effects did you see, if any?

Dr Molsberry: Our analyses considered both diet at baseline (1986) and long-term diet (1986-2006) in relation to prodromal features of Parkinson disease. While we found that both baseline diet and long-term diet were associated with having multiple prodromal features, the results were particularly strong for long-term diet. For example, we found that those in the highest quintile of long-term adherence to the alternate Mediterranean diet had 0.67 times the odds of having 3 or more vs 0 prodromal Parkinson features, compared with those in the lowest quintile.

C360: Which diet(s) had the highest potential to stave off Parkinson disease? Did any of your findings around specific diets surprise you?

Dr Molsberry: We investigated 2 diet patterns, the alternate Mediterranean diet and the Alternative Healthy Eating Index. Both diet patterns emphasize consumption of fruits and vegetables, nuts, and legumes and discourage intake of red meat and processed foods. The results from our analyses were highly similar for both diet patterns, suggesting that it is more important to follow a healthy overall diet pattern rather than a specific pattern, such as the Mediterranean diet. These results are consistent with previous analyses in our cohorts on diet pattern and risk of clinically manifest Parkinson disease, as well as other studies in the literature, so they were not particularly surprising to us.

C360: What clinical pearls can nutritionists and other health care professionals take away from your analysis? What is the take home message here? 

Dr Molsberry: It is important to note that our study does not establish a causal role between following a healthy diet pattern and risk of prodromal Parkinson disease features nor does it explore whether adhering to a healthy diet pattern can slow or prevent the development of clinically manifest Parkinson disease among those with prodromal features of Parkinson disease.

That being said, our investigation adds to a previous body of literature suggesting that adherence to a healthy diet pattern may reduce risk of Parkinson disease and prodromal features of Parkinson disease. For nutritionists and other health care professionals, the takeaway message may be to continue encouraging your patients to follow a healthy diet pattern, which, based on our findings, need not necessarily be a specific diet pattern as long as it is a healthy diet pattern.


  1. Molsberry S, Bjornevik K, Hughes KC, Healy B, Schwarzchild M, Ascherio A. Diet pattern and prodromal features of Parkinson’s disease. Neurology. Published online August 19, 2020.