TOPLINE:

Frequent insomnia symptoms were linked to a more than 50% increased risk for Parkinson’s disease (PD), a new study spanning more than 25 years showed. Genetic liability to insomnia also showed an association with risk for incident PD, suggesting that insomnia may be a risk factor rather than just a prodromal symptom.

METHODOLOGY:

• Researchers analyzed data for more than 73,000 participants without PD (mean age, 46 years) from the National FINRISK Study surveys, which were conducted every 5 years from 1972 to 2012 in Finland.
• Data for participants who self-reported baseline symptoms of insomnia (never, sometimes, or often) and/or nighttime sleep duration (short, < 7 hours; long, > 8 hours; or very long, > 9 hours) were linked to health register data on incident PD.
• Overall, 2679 participants developed PD over a mean follow-up of 24.6 years. The analysis also accounted for the competing risk for death.
• Polygenic risk scores for insomnia and sleep duration were examined in association with PD, using approximately 1 million genetic variants per score.

TAKEAWAY:

• Experiencing insomnia “sometimes” was associated with increased risk for PD (incidence rate ratio [IRR], 1.14), with insomnia experienced frequently/often showing an even stronger association (IRR, 1.54). Although short or long sleep duration was not linked to risk for PD, a very long sleep duration was associated with PD (IRR, 1.44).
• When accounting for the competing risk for death, only frequent insomnia was linked to increased risk for PD (IRR, 1.26).
• In sensitivity analyses restricted to individuals with at least 20 years of follow-up, frequent insomnia remained linked to risk for PD (IRR, 1.37).
• The polygenic risk score for insomnia was associated with incident PD (IRR, 1.13), but no genetic measures of sleep duration were associated with significant PD risk.

IN PRACTICE:

“In this long-term cohort study, both self-reported insomnia and genetic liability to insomnia were associated with an increased risk of incident Parkinson’s disease, suggesting insomnia is a potential risk factor rather than solely a prodromal symptom,” the investigators wrote.

“However, the attenuated association of insomnia with the cumulative incidence of Parkinson’s disease in the subdistribution hazard model accounting for the competing risk of death suggest a modest real-life effect,” they added.

SOURCE:

The study was led by Sonja Sulkava, MD, PhD, Finnish Institute for Health and Welfare, Helsinki, Finland. It was published online on March 26 in Brain Communications.

LIMITATIONS:

The study used a single one-point question on insomnia and subjective sleep length instead of a validated sleep questionnaire and objective sleep measurement, which may have limited the precision of exposure assessment. Unmeasured confounding could not be ruled out because the study did not account for candidate risk or prodromal factors for PD, which are strongly linked to insomnia. 

DISCLOSURES:

The study was funded by the Finnish Parkinson Foundation and Finnish Sleep Research Society. The investigators reported having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.