Nightmares Could Be Early Warning Sign of Parkinson's in Older Men

Bad dreams could be an early indicator of Parkinson's disease, scientists have found.

In a paper published on Wednesday in the journal eClinicalMedicine, researchers from the University of Birmingham said that in their test cohort of older men, those who were experiencing frequent bad dreams were twice as likely to be later diagnosed with Parkinson's disease compared to those who didn't have regular nightmares.

Parkinson's disease is the second most common neurodegenerative disease in the U.S. after Alzheimer's. It often leads to significant disability for affected individuals and it negatively impacts a patient's quality of life. There is currently no cure for the disease.

Patients experience a variety of motor symptoms, most commonly tremors, but they also have a range of other problems, which can include depression, constipation, urinary dysfunction and excessive daytime sleepiness.

The researchers found that in a group of 3,818 men aged 67 years or older, who were Parkinson's-free when they enrolled in the study, frequent distressing dreams (one or more per week) indicated an increased risk for developing Parkinson's.

bad dreams
A new study has shown that bad dreams could be an indicator of Parkinson's disease. Pictured, a stock image of a man lying awake at night. iStock / Getty Images Plus

In this study, using data collected over a 12-year period, it was shown that the Parkinson's risk indicated by having frequent distressing dreams was three times greater within the five years leading up to a Parkinson's diagnosis, although this association decreased significantly during the subsequent seven-year period.

Previous studies had shown that people with Parkinson's disease experience nightmares and bad dreams more frequently than adults who have not been diagnosed with the disease, but this is the first study to look into whether nightmares may be associated with an increased risk for developing Parkinson's.

"The findings of this longitudinal study are consistent with prior cross-sectional studies, which demonstrated that distressing dreams are very common in people with Parkinson's disease and that people with Parkinson's disease are significantly more likely to report having frequent distressing dreams than adults in the general population," the authors wrote.

"Indeed, studies have shown that 17 percent of patients with non-demented Parkinson's report weekly nightmares, and this increases to 78 percent for patients with Parkinson's disease dementia," the report continued. "In contrast, estimates for the prevalence of weekly nightmares in the general population range from 2 percent to 5 percent."

However, the study's authors said further research would be needed.

This study relied on self-reported doctor diagnosis to determine if a patient had Parkinson's, which might have led to an underestimation of the association between dreams and the disease due to some cases being missed or misdiagnosed.

Additionally, as the authors wrote, "the questionnaire item used to assess distressing dreams does not clearly distinguish between frequent bad dreams (i.e., distressing dreams without awakenings) and frequent nightmares (i.e., distressing dreams with awakenings). As such, it is not possible to determine whether the associations with Parkinson's may vary by distressing dream subtype."

This research was also only carried out on a group of older men, meaning that the results might not be applicable to older women and younger adults.

One issue with Parkinson's disease is that by the time most people figure out they've got the disease, they've already lost between 60 to 80 percent of dopamine-releasing neurons in their brain stem. This research could help detect at-risk individuals earlier in life by screening for late-onset distressing dreams, leading to earlier diagnosis and potentially more effective treatments.