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Parkinson's disease is often perceived primarily as a motor disorder. However, it frequently presents with non-motor symptoms, including psychiatric conditions. Historically, researchers have believed that the onset of Parkinson's disease often coincides with related psychiatric disorders.

In a groundbreaking study, the largest of its kind, researchers analyzed data from 250,000 individuals with autism, intellectual disabilities, or both. Through long-term tracking, they found that these populations are three times more likely to develop Parkinson's disease symptoms compared to the general population.

This research was presented at an international autism research conference in Australia, where the study's co-author, Gregory Wallace, a developmental psychologist from George Washington University, highlighted its importance. He emphasized that understanding the potential health issues that may arise as autistic individuals age is crucial for their healthcare.

Robert Hendren, a psychiatrist at the University of California, San Francisco, echoed this sentiment, stating, "The better prepared people are, the more likely they are to minimize or even eliminate the impact of Parkinson's disease."

Autism is a developmental disorder primarily affecting social interaction and communication. It affects about one in 100 children and was first reported in the 1940s. It wasn't until the 1970s that autism was recognized globally as a distinct condition rather than just a symptom. Since then, diagnostic criteria have evolved significantly, which has made it challenging to conduct long-term studies on aging autistic individuals. This study thus fills a crucial gap in our understanding.

Due to the evolving diagnostic criteria, recruiting older autistic individuals for long-term studies is challenging. This study stands out for its scale and duration, offering valuable insights into the aging process in autistic individuals.

The research builds on previous studies. In 2015, Piven and colleagues published a study involving 37 autistic adults, finding that 12 had Parkinson's disease. Despite the small sample size, the study suggested a higher prevalence of Parkinson's disease in autistic individuals. Genetic research has also found that the PARK2 gene, associated with Parkinson's disease, is linked to autism.

To ensure more reliable results, Wallace and his team analyzed medical records of 247,539 individuals aged 45 and older from 2014 to 2016. Among them, 23,686 had autism without intellectual disabilities, 223,853 had intellectual disabilities without autism, and 13,302 had both conditions.

The medical records revealed that 5.98% of autistic individuals without intellectual disabilities, 6.01% of those with intellectual disabilities but without autism, and 7.31% of individuals with both conditions were diagnosed with Parkinson's disease. These diagnoses were made in individuals over the age of 55. Compared to the general population, these groups had at least three times the risk of developing Parkinson's disease.

The underlying reasons why individuals with autism and intellectual disabilities are more prone to Parkinson's disease remain unclear. Researchers speculate that brain health and development play significant roles. Moreover, medical reports suggest a possible link with certain medications.

Many autistic individuals experience anxiety and may exhibit aggressive behaviors, leading to the use of antipsychotic medications. Reports indicate that 20%-34% of autistic children in the U.S. have used these medications, which can have side effects resembling Parkinson's disease symptoms.

In further analyses, Wallace and his team excluded individuals who had taken medications that might induce Parkinson's disease during the study period. Even after this exclusion, the prevalence of Parkinson's disease remained high among those with autism and intellectual disabilities. This suggests that other factors, besides medication, contribute to the increased risk in these populations.

Future research will focus on the age of onset of Parkinson's disease in individuals with autism and intellectual disabilities, aiming to determine whether they exhibit symptoms earlier than the general population. In the coming years, we may uncover more definitive answers to these critical questions.

Reference:

https://www.nature.com/articles/d41586-024-01572-w