Frequent Nightmares Could Be an Early Sign of Parkinson's, Study Finds

The development of nightmares later in life could be an early sign of Parkinson's disease, according to new research in older men.

Distressing dreams have long been associated with the neurological disease, especially among men, but this is the first study to investigate whether these symptoms are a warning of Parkinson's or a byproduct of the condition.

Tracking the health of 3,818 older men with typical brain functioning for 12 years, researchers found those who experienced frequent nightmares were twice as likely to develop Parkinson's.

Most of the diagnoses occurred within the first five years of the study.

The results suggest older adults could be screened for Parkinson's by asking them about the content of their dreams. Early interventions could then be employed to help stall the possible onset of physical symptoms, like tremors, stiffness, and slowness.

"Although it can be really beneficial to diagnose Parkinson's disease early, there are very few risk indicators and many of these require expensive hospital tests or are very common and non-specific, such as diabetes," explains neurologist Abidemi Otaiku from the University of Birmingham in the UK.

"While we need to carry out further research in this area, identifying the significance of bad dreams and nightmares could indicate that individuals who experience changes to their dreams in older age – without any obvious trigger – should seek medical advice."

The link between sleep and Parkinson's is one that researchers have been investigating for several years now. 

Roughly a quarter of Parkinson's patients report frequent distressing dreams from the time of diagnosis, and some report experiencing bad dreams up to 10 years before they were diagnosed.

Past studies suggest that people with Parkinson's disease are four times more likely to experience frequent nightmares than those in the general population.

Yet until now, it hasn't been clear if these symptoms were a byproduct of Parkinson's or prodromal, which is the term scientists use for minor symptoms that appear before major symptoms arrive on the scene.

Men with Parkinson's tend to have more disturbing dreams than women with Parkinson's, but why that is remains unclear.

One hypothesis is that the late onset of nightmares is an early sign of neurodegeneration in some men.

Women are significantly more likely to experience regular nightmares early in life, but after age 65, men start to catch up.

Perhaps something is changing in the frontal cortex, which regulates emotion during sleep, as the male brain ages.

Researchers are now planning to use electroencephalography to figure out what that something might be.