Autistic Individuals at Triple Risk for Parkinson’s-Like Symptoms, Study Finds

A study involving a quarter of a million people with autism, intellectual disabilities, or both has revealed that their risk of developing Parkinson’s disease symptoms is three times higher than that of the general population. Additionally, the study identifies an increased risk among older adults with various intellectual disabilities.

Researchers Call for Deeper Study of Parkinson’s Risk in Autism and Intellectual Disabilities

The study, the largest of its kind, calls for further investigation into the connections between these conditions, researchers say. The findings were presented at the International Society for Autism Research annual meeting in Melbourne, Australia, on 16 May, and have not yet undergone peer review.

“These results are a big deal as we think about planning and what we should be screening or looking for as autistic people age,” says Gregory Wallace, a developmental neuropsychologist at George Washington University in Washington DC.

Robert Hendren, a psychiatrist at the University of California, San Francisco, concurs. “The better prepared people can be, the better chance there is of minimizing the effects, or maybe even eliminating them,” he says.

Parkinson’s Risk Up to 7.31% in Aging Autistic Adults

Few studies have explored the health effects experienced by autistic adults as they age. When autism was first described in the 1940s, “it was seen as a disorder of infants,” says Joseph Piven, a psychiatrist at the University of North Carolina at Chapel Hill.

Autism became a distinct diagnosis in the 1970s, and the criteria for its characterization have changed multiple times since then. These evolving criteria and the difficulty of recruiting aging participants for studies have made long-term tracking challenging, explains Gregory Wallace, a developmental neuropsychologist at George Washington University in Washington DC. “Part of the reason we know so little about this, and why this is in its infancy, is because we know so little more broadly about aging and autism,” Wallace says.

Previous studies have highlighted that autistic individuals exhibit disproportionately high rates of parkinsonism—symptoms commonly associated with Parkinson’s disease, such as tremors, sudden freezing while walking, and difficulty holding a posture—compared to the general population. One of the pioneering studies on this issue, published in 2015 by Joseph Piven and his colleagues, investigated 37 adults with autism and discovered that 12 had parkinsonism. However, the small sample sizes in these studies have undermined the reliability of their findings. “Many autistic people, when they’re younger, have motoric symptoms or issues with motor functioning,” Wallace says. “We want to figure out if it is parkinsonism, a broader array of these motoric features, or if it is a neurodegenerative process.” Genetic studies have also linked autism to mutations in the PARK2 gene, which is associated with Parkinson’s disease.

Parkinsonism Rates Exceed 6% in Individuals with Intellectual Disabilities

Wallace and his team analyzed medical records spanning from 2014 to 2016 for 247,539 individuals aged 45 and above in the United States. Among them, 23,686 were diagnosed with autism, 223,853 had an intellectual disability without autism, and 13,302 had both conditions concurrently.

The analysis showed that parkinsonism was diagnosed in 5.98% of autistic individuals without intellectual disability, 6.01% of those with intellectual disability but not autism, and 7.31% of individuals with both conditions. Notably, all individuals diagnosed with parkinsonism were aged over 55. This work clearly shows that these rates far exceed those in the general population, where Parkinson’s-like symptoms are observed in only 0.11% to 1.85% of individuals in the same age bracket.

Exploring Early Onset Parkinsonism in Autism and Intellectual Disabilities

Researchers suggest that there may be an unidentified aspect of brain health or development linking Parkinsonism to autism and intellectual disabilities. This link could also be influenced by medication usage. Studies conducted in the United States indicate that 20–34% of children with autism receive antipsychotic medications to manage behaviors such as irritability, aggression, self-injury, and social withdrawal, which are considered “challenging”. Some antipsychotic medications are known to have parkinsonism as a potential side effect.

In a subsequent analysis presented at the same meeting, Wallace and his team excluded individuals who had taken parkinsonism-inducing medications during the study period. Their findings, as reported by Nature, suggest that the rates of parkinsonism remained elevated even in this narrowed-down group. Future research endeavors should focus on determining whether individuals with autism and intellectual disabilities experience the onset of parkinsonism symptoms earlier than those in the general population.

Wallace emphasized the need for longitudinal studies in order to accurately determine the pathological nature. “Critically, for us to understand if it’s neurodegenerative, we need to follow people over time.” 

The necessity for considering treatment strategies is echoed by Piven. “We need to think about how to treat it,” he adds. “We need to think about screening people with autism for parkinsonian features.” Hendren concurs, highlighting the complexity of the issue. Hendren agrees. “It’s going to be a complex picture,” he says. “And we need to do it all together.” parkinson’s disease, parkinson’s symptoms, parkinson’s disease symptoms, parkinsons, what is parkinson’s disease, Rising, substantia nigra, does Parkinson’s affect cognition, Parkinson’s UK, when was Michael J. Fox diagnosed with Parkinson’s disease, Parkinson’s news today, Insomnia, Substantia nigra, Prevalence, Neurotransmitter, Arthritis, Rising

Author

Bernice Lottering