Frequent distressing dreams and Parkinson’s disease

To investigate association between frequent distressing dreams and the risk of incident Parkinson’s Disease, 3818 men aged ≥67 years were enrolled from the US-based multicenter Osteoporotic Fractures in Men (MrOS) trial. None had Parkinson’s disease at study entry. Data for Point 5H of the Pittsburgh Sleep Quality Index, which specifically enquires about the frequency of bad dreams in the past month was available for the selected participants “During the past month, how often have you had trouble sleeping because you have bad dreams?”

Analysis of data over 12-year follow-up revealed 91 cases (2.4%) of new onset Parkinson’s disease during a mean follow-up of 7.3 years. The study subjects who reported having frequent distressing dreams at the beginning of the study were twice more likely to develop incident Parkinson’s disease with odds ratio of 2.01 compared to those who did not have such dreams.

Evaluation of risk as per follow-up time showed that during the first five years after recruitment into the study, the risk for incident Parkinson’s disease was increased more than 3-folds in those who had reported having distressing dreams frequently with odds ratio of 3.38. However, in the following 7 years, this association did not remain significant with OR of 1.55. Patients who developed incident Parkinson’s disease were more likely to be depressed and have sleep maintenance insomnia. After adjusting for other characteristics such as age, race, education, smoking status, alcohol intake, depression, sleep onset and sleep maintenance insomnia, diabetes, hypertension, physical activity, medication use, the association between distressing dreams and incident Parkinson’s disease continued to be significant.

This study has demonstrated for the first time an association between frequently occurring distressing dreams and incident Parkinson’s disease. Since the risk was found to be significantly higher within the first five years from baseline, this, the author says, could be suggestive of frequent distressing dreams as “a prodromal symptom” of Parkinson’s disease. Hence, inclusion of distressing dreams in older age in the screening protocol may help in the early identification of individuals at increased risk for developing Parkinson’s disease leading to early diagnosis and intervention. They could be experiencing bad dreams much before the cardinal symptoms of Parkinson’s disease, namely tremors, rigidity and bradykinesia, begin to manifest.

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