Low Levels of Some Fatty Acids Found in Parkinson’s Patients

People with Parkinson’s disease have lower-than-normal levels of certain fatty acids in their blood, which is not explained by dietary differences, a new study shows.

The low levels of some of these fatty acids among Parkinson’s patients are associated with more severe motor symptoms, while high levels of other fatty acids are linked to more severe non-motor symptoms, the study also found.

These findings suggest “that fatty acid metabolism is altered in [Parkinson’s disease],” the researchers wrote.

The study, “Dietary intake and plasma levels of polyunsaturated fatty acids in early-stage Parkinson’s disease,” was published in Scientific Reports.

Polyunsaturated fatty acids, or PUFAs, are a type of fat molecule with a particular chemical structure that play important roles in the body. Among their functions is helping to form the membranes of nerve cells.

Most PUFAs can be synthesized to some extent within the human body, but doing so takes a lot of energy. Thus, most mammals, including humans, require at least some amount of PUFAs to be obtained through their diet. Two PUFAs — one called alpha-linolenic acid or ALA, and the other known as linoleic acid, or LA — cannot be made in the human body, and must be obtained through a person’s diet.

Prior research has indicated that levels of PUFAs may be abnormal in people with Parkinson’s, but the role of these molecules in the disease is unclear. Additionally, most prior studies have either looked at dietary intake or at levels of PUFA in the blood, but not both.

Now, researchers in South Korea assessed PUFA intake through dietary questionnaires — and also measured levels of PUFA in the blood. The team analyzed 38 people with Parkinson’s and 33 controls, or people without the disease. There were no statistically significant demographic differences between the groups, though the researchers noted that there were comparatively more males and people with diabetes among the Parkinson’s patients.

Based on the dietary questionnaires, the researchers reported “no differences in dietary intake including total energy, total fat, cholesterol, total fatty acids, saturated fatty acids, monounsaturated fatty acids, and PUFA” between the Parkinson’s patients and the controls.

However, plasma (blood) levels of three PUFAs — ALA, LA, and arachidonic acid, known as AA — were significantly lower, on average, among those with Parkinson’s. The researchers noted that, while there were statistically significant differences in average levels between the patients and controls, “individual values [of plasma PUFA levels] overlapped between the two groups.”

Based on the specific biochemical properties of these PUFAs, the researchers speculated that the reason for this difference, despite similar dietary intake of these fatty acids, could be that the brains of those with Parkinson’s consume more of certain PUFAs than healthy brains.

However, they also noted that it’s impossible to make a definitive conclusion about cause-and-effect from these data. Indeed, it also is possible that low PUFA levels predispose toward Parkinson’s.

Statistical analyses, which accounted for age and sex, revealed a significant negative correlation between motor symptom severity and plasma levels of ALA and LA among those with Parkinson’s — in other words, patients with lower levels of these fatty acids tended to have more severe motor symptoms.

By contrast, levels of AA and another PUFA called docosahexaenoic acid (DHA) were positively correlated with the severity of non-motor symptoms. That positive correlation means that those with higher plasma levels of these PUFAs tended to have more severe non-motor symptoms.

No associations were found between plasma levels of PUFA and disease duration, constipation, activities of daily living, disease stage, or total anti-parkinsonian medication.

That higher levels of some PUFAs were associated with milder symptoms, while high levels of other PUFAs were associated with more severe symptoms, demonstrates that “the clinical effects of PUFA in PD [Parkinson’s disease] are not straightforward,” the researchers wrote.

Noted limitations of this study include its small sample size, and the fact that the study was conducted in a single place, with specific cultural tendencies regarding diet. As noted by the investigators, people in Korea tend to eat more seafood than individuals living in other parts of the world. As such, the team called for larger and more wide-ranging studies to better understand the role of PUFAs in Parkinson’s.