Connecting Autism Spectrum Disorders With Parkinsonism

In recent years, the prevalence of autism spectrum disorders (ASDs) has increased, affecting one in 44 children in the US. Challenges in communication, social interaction, and repetitive behaviors mark these complex and lifelong neurodevelopmental conditions. As more individuals with ASD progress into adulthood, there is growing concern about their vulnerability to age-related neurodegenerative disorders, according to a study published online in Wiley Online Library.

Research shows that middle-aged and older adults with ASD, particularly those without intellectual disabilities, are at a higher risk of experiencing Parkinsonism, which includes symptoms like bradykinesia and poor balance. This link between ASD and Parkinsonism suggests a potential association between the two conditions, even when excluding the influence of atypical antipsychotic medications.

Researchers also suggest genetic overlap between Parkinson disease (PD) and ASD, with certain genes associated with PD being implicated in ASD. This connection has biological plausibility, as both conditions may share similar underlying mechanisms, particularly related to dopamine regulation.

Despite these connections, little research focuses on the clinical, genetic, and pathophysiological aspects of the association between ASD and Parkinsonism. Researchers conducted a systematic review to assess the current evidence to address this gap comprehensively. The review encompassed clinical studies, genetic studies, and case reports highlighting the presence of Parkinsonism in individuals with ASD.

This systematic review revealed that Parkinsonism, including Parkinson's disease, is more prevalent in adults with ASD than non-ASD controls, regardless of age group. The evidence suggests that females may be more susceptible to Parkinsonism than males. In contrast, the link between children and adolescents with ASD and Parkinsonism is unclear, with bradykinesia being more common in these groups.

Genetic studies revealed associations between certain genes, particularly PARK2, with ASD and PD. Dopaminergic pathways appear to play a significant role in the pathogenesis of ASD, given their role in social behavior and movement control. Brain imaging studies further support abnormalities in dopaminergic structures in individuals with ASD.

Challenges in evaluating Parkinsonism in individuals with ASD include the frequent use of atypical antipsychotics and difficulties in diagnosing and monitoring Parkinsonian symptoms in this population. Future studies should consider long-term follow-up, functional imaging, and the identification of suitable biomarkers for diagnosing and monitoring Parkinsonism in ASD patients.

"The prevalence of ASD has been steadily rising over the past decades, especially among those who have progressed to adulthood," said researchers. Genetic associations and shared pathophysiological mechanisms between the two conditions warrant further investigation.

"Pathophysiologic studies in transgenic animal models and human organoid models derived from ASD patients with and without Parkinsonism can identify novel clues that may uncover potential therapeutic targets. The additional risk of Parkinsonism observed in ASD patients, as well as genetic associations and common pathogenetic mechanisms underlying the two conditions, are key areas to be further investigated," said researchers.

Reference

Aaron Shengting Mai, Chun En Yau, Fan Shuen Tseng, Joel X, Wang Q, Tan E. Linking autism spectrum disorders and parkinsonism: clinical and genetic association. Wiley Online Library. Published online February 4, 2023. Accessed October 18, 2023. doi:https://doi.org/10.1002/acn3.51736