A recent study reveals that people aged over 50 who develop anxiety are more than twice as likely to be diagnosed with Parkinson’s disease compared to those without anxiety. This finding, published in the British Journal of General Practice, highlights the potential role of anxiety as an early indicator of Parkinson’s, prompting further investigation into its implications for early diagnosis and treatment.

Parkinson’s disease is the second most common neurodegenerative disorder globally, projected to affect over 14 million people by 2040 due to increasing life expectancy. Early detection is crucial for managing the disease, but recognizing the early, non-motor symptoms of Parkinson’s remains a challenge. Anxiety, a common condition among older adults, has been observed to precede Parkinson’s, but the exact relationship has been unclear.

Previous studies indicated an increased risk of Parkinson’s in people with anxiety but did not fully account for factors like lifestyle and socioeconomic status. This study aimed to fill these gaps by investigating the link between new-onset anxiety and the later diagnosis of Parkinson’s, considering various confounding variables.

The researchers utilized data from the IQVIA Medical Research Database, which includes de-identified electronic health records from the Health Improvement Network (THIN). This database contains information from over 700 general practices in the United Kingdom, representing a diverse patient population.

The study focused on individuals aged 50 to 99 who were registered with participating practices between January 2008 and December 2018. The participants were divided into two groups: those with a new diagnosis of anxiety and those without anxiety. Each person with anxiety was matched with four controls based on age and sex, creating a dynamic cohort where individuals could switch from the control to the anxiety group if they later developed anxiety.

To analyze the data, the researchers used survival regression models to estimate the risk of developing Parkinson’s over time, adjusting for factors such as age, sex, socioeconomic status, lifestyle choices (smoking, alcohol consumption, body mass index), and relevant health conditions (severe mental illness, head trauma, dementia). The models were built stepwise to explore associations while accounting for these variables.

The study included 38,510 men and 70,925 women with a first episode of anxiety and 324,670 men and 553,586 women without anxiety. Over the follow-up period, 331 individuals in the anxiety group were diagnosed with Parkinson’s, with a median time to diagnosis of 4.9 years.

The incidence of Parkinson’s in the anxiety group was 1.02 per 1,000 person-years, compared to 0.49 per 1,000 person-years in the non-anxiety group. After adjusting for confounding factors, the risk of Parkinson’s was found to be more than twice as high in people with anxiety (hazard ratio of 2.1). The study also identified several prodromal symptoms associated with Parkinson’s in individuals with anxiety, including sleep problems, depression, fatigue, constipation, cognitive impairment, and specific motor symptoms like tremor and rigidity.

Co-lead author Juan Bazo Avarez of University College London said: “Anxiety is known to be a feature of the early stages of Parkinson’s disease, but prior to our study, the prospective risk of Parkinson’s in those over the age of 50 with new-onset anxiety was unknown. By understanding that anxiety and the mentioned features are linked to a higher risk of developing Parkinson’s disease over the age of 50, we hope that we may be able to detect the condition earlier and help patients get the treatment they need.”

While the study provides valuable insights, it has some limitations. The data relied on electronic health records, which are primarily collected for clinical purposes and may underreport mental health conditions due to stigma or incomplete documentation. This underreporting could mean the actual association between anxiety and Parkinson’s is even stronger than observed.

Additionally, the study population was limited to those aged 50 and older, excluding younger individuals who might have different risk profiles. The findings may not be generalizable to other populations, particularly those outside the United Kingdom or with different healthcare systems.

Future research should aim to explore the severity of anxiety and its impact on the risk of Parkinson’s. Understanding the specific mechanisms linking anxiety to Parkinson’s could lead to better early detection and management strategies. Moreover, investigating anxiety in conjunction with other prodromal symptoms might provide a more comprehensive understanding of the disease’s early stages.

“Anxiety is not as well researched as other early indicators of Parkinson’s disease,” said co-author Anette Schrag. “Further research should explore how the early occurrence of anxiety relates to other early symptoms and to the underlying progression of Parkinson’s in its early stages. This may lead to better treatment of the condition in its earliest stages.”

The study, “Risk of Parkinson’s disease in people aged ≥50 years with new-onset anxiety: a retrospective cohort study in UK primary care,” was authored by Juan Carlos Bazo-Alvarez, Danielle Nimmons, Kate Walters, Irene Petersen and Anette Schrag