Genetic Analysis Links Psoriasis With Faster Disease Progression
Among people with Parkinson’s disease, those with the skin disease psoriasis tend to experience slightly faster disease progression, according to a new analysis of genetic data.
“These findings provided a better understanding of the role of psoriasis in the pathogenesis [disease development] of [Parkinson’s], and had clinical implications for patients and clinicians,” researchers wrote.
Results were detailed in the study, “Psoriasis and Progression of Parkinson’s Disease: a Mendelian Randomization Study,” published in The Journal of the European Academy of Dermatology and Venereology.
Psoriasis is an inflammatory disease that causes a rash with itchy, scaly patches on the skin, usually affecting the knees, elbows, torso and/or scalp. Previous studies have suggested that people with psoriasis are at increased risk of developing Parkinson’s.
In this study, researchers in China conducted a Mendelian randomization analysis to further explore the relationship between psoriasis and Parkinson’s.
Mendelian randomization, or MR, is an analytical strategy predicated on the idea that certain genetic variations make an individual more or less susceptible to developing a given condition (e.g., psoriasis). So, if a person’s genetic code is known, researchers can assign a risk score based on which disease-associated risk variants they have or don’t have.
Importantly, the risk scores used in a MR analysis are dependent only on a person’s genetic code; they are unaffected by environmental and lifestyle factors. Because of this, “the MR approach is less susceptible to confounding and reverse causality bias” compared to other analytical approaches, the researchers wrote.
Here, the researchers used previously established genetic associations to assign psoriasis risk scores for Parkinson’s patients, then used MR analysis to measure relationships between the psoriasis risk scores and clinical outcomes related to Parkinson’s. The analysis included data from more than 4,000 Parkinson’s patients.
The results revealed that an increase in psoriasis risk score was linked with faster progression of motor symptoms (as measured by Hoen and Yahr staging), as well as faster development of dementia or depression. The magnitude of the results was relatively small, the researchers noted, but the associations remained statistically significant after “extensive sensitivity analyses” done to validate the results.
“The results showed that psoriasis was associated with faster progression, and increased risk of dementia and depression of [Parkinson’s],” the scientists concluded.
The team noted that out-of-control inflammation and mitochondrial dysfunction have been implicated in the development of both Parkinson’s and psoriasis, which may help explain these results. The researchers stressed that more, larger studies are needed to validate these findings.
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