Parkinson Disease Prodromal Symptoms Common Among Older Adults

Many community-dwelling older adults have 1 or more prodromal signs or symptoms of Parkinson disease (PD), according to results of a study published in Neurology.

By the time PD is diagnosed, approximately 75% of dopamine-producing cells have already been lost. To prevent this early cell loss and slow disease progression, it is crucial to identify the prodromal signs and symptoms of PD.

Researchers at the University of Pittsburgh analyzed data from older adults enrolled in the Monongahela-Youghiogheny Healthy Aging Team study and the Study of Muscle, Mobility, and Aging. They assessed participants for PD risk factors and prodromal signs and symptoms. The researchers also examined the association between risk factors, prodromal signs, and dopaminergic nerve terminal density. The probability of prodromal PD, defined as a posterior probability greater than 30%, was calculated based on Movement Disorders Society criteria.

These findings support the utility of using composite measures of signs and symptoms to screen for risk of PD at the population level.

A total of 231 patients were included in the analysis, of whom the mean (SD) age was 75.1 (4.5) years, 59.3% were women, and 91.8% were White. The frequency of participants having 1, 2, or 3 or more prodromal symptoms was 22.08%, 25.11%, and 31.6%, respectively. The most common prodromal symptom was cognitive deficit, followed by subthreshold parkinsonism, urinary dysfunction, and olfactory dysfunction. Overall, 7.8% of the population was classified as having prodromal PD.

Individuals with prodromal PD had significantly slower dual task walking speed (P <.001) and greater dual task cost (P <.001) than those without prodromal PD. They also showed a trend toward slower usual walking speed (P =.057).

Imaging revealed that age- and sex-adjusted dihydrotetrabenazine ([¹¹C]DTBZ) binding was significantly decreased in all brain regions examined in the prodromal PD group, including the posterior putamen (P =.014), mean putamen (P =.013), mean caudate (P =.015), and mean striatum (P =.014). Overall, the probability of prodromal PD was significantly correlated with adjusted [¹¹C]DTBZ binding (r, -0.215; P =.001).

Stratified by specific signs and symptoms, hyposmia was associated with lower [¹¹C]DTBZ binding in the posterior putamen compared with normosmia (b, -0.179; 95% CI, -0.332 to -0.026; P =.022), whereas depression, parkinsonism, cognition, and urinary function were not.

When [¹¹C]DTBZ binding thresholds were used to define prodromal PD, 3.5%, 6.5%, and 10.0% of individuals were classified as having prodromal PD at thresholds of greater than 80%, greater than 50%, and greater than 30%, respectively.

Study limitations include a lack of population diversity.

The study authors concluded, “These findings support the utility of using composite measures of signs and symptoms to screen for risk of PD at the population level.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.