Tremor, restless legs syndrome, schizophrenia among risk factors linked to PD
An increased risk for Parkinson’s disease was associated with a range of factors, comorbidities and prodromal features, some of which may appear 5 to 10 years prior to diagnosis, according to a study in JAMA Neurology.
“Prodromal features of Parkinson’s disease can start more than a decade before the typical clinical symptoms allow a diagnosis,” Anette Schrag, MD, PhD, of the department of clinical and movement neurosciences at University College London, and colleagues wrote. “In addition, there is increasing evidence for a number of possible risk factors that may predispose to the manifestation of the disease or facilitate development or spread of pathological lesions.”
Schrag and fellow researchers aimed to understand the link between risk factors and prodromal features — including lifestyle factors, comorbidities and potential extracerebral manifestations — and subsequent diagnosis of PD.
In a case-control study, researchers utilized insurance claims of outpatient consultations of patients with German statutory health insurance between January 2011 and December 2020 to identify 138,345 individuals with a PD diagnosis (mean age, 75.1 years; 53.3% men) and 276,690 controls matched on age, sex, region and earliest year of outpatient encounter. All participants were monitored for a mean of 6 years.
According to results, risk factors and prodromal features associated with PD included traumatic brain injury (OR, 1.62; 95% CI, 1.36-1.92), alcohol misuse (OR, 1.32; 95% CI, 1.21-1.44), hypertension (OR, 1.29; 95% CI, 1.26-1.31), anosmia (OR, 2.16; 95% CI, 1.59-2.93) and parasomnias (including rapid eye movement sleep behavior disorder; OR, 1.62; 95% CI, 1.42-1.84).
Researchers also identified links to restless legs syndrome (OR, 4.19; 95% CI, 3.91-4.5), sleep apnea (OR, 1.45; 95% CI, 1.37-1.54), epilepsy (OR, 2.26; 95% CI, 2.07-2.46), migraine (OR, 1.21; 95% CI, 1.12-1.29), bipolar disorder (OR, 3.81; 95% CI, 3.11-4.67) and schizophrenia (OR, 4.48; 95% CI, 3.82-5.25).
Conditions associated with PD 5 to 10 years before diagnosis included tremor (OR, 4.49; 95% CI, 3.98-5.06), restless legs syndrome (OR, 3.73; 95% CI, 3.39-4.09), bipolar disorder (OR, 3.8; 95% CI, 2.82-5.14) and schizophrenia (OR, 4; 95% CI, 3.31-4.85). Positive associations also were made with skin disorders, gastrointestinal disorders, conditions with a potential inflammatory component and diabetes types 1 and 2.
“Given the size and study period, we believe that this case-control study has generated valuable hypotheses on the associations found between PD and certain risk factors, comorbidities and prodromal symptoms in a representative population,” Schrag and colleagues wrote.