Bad dreams may be an early sign of Parkinson's disease, according to new research. Older men experiencing frequent nightmares are over three times as likely to be later diagnosed with the disease.
The finding offers hope of a screening programme - enabling patients to be prescribed drugs sooner. People with the devastating disorder are prone to scary dreams. But using them as a warning has not been previously considered.
Lead author Dr Abidemi Otaiku, a brain specialist at the University of Birmingham, said: "Although it can be really beneficial to diagnose Parkinson's 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.
"While we need to carry out further research in this area, identifying the significance of bad dreams and nightmares could indicate individuals who experience changes to their dreams in older age - without any obvious trigger - should seek medical advice."
His team analysed data on 3,818 participants living independently in the US who were tracked for 12 years. At the outset they completed a range of surveys, one of which included a question about sleep quality.
Those reporting bad dreams at least once a week were followed up at the end of the study period, during which time 91 cases of Parkinson's were diagnosed. Overall, those having regular bad dreams were twice as likely to develop the disease compared to those who did not.
But most of the diagnoses happened in the first five years of the study - when risk more than tripled compared to peers who slept peacefully. The results suggest older adults with Parkinson's are likely to begin having nightmares a few years before developing symptoms of tremors, stiffness and slowness of movement.
They also shows dreams can reveal important information about brain structure and function and may prove to be an important target for neuroscience research. Dr Otaiku and colleagues plan to use EEG (electroencephalography) brain scans to look at the biological reasons for dream changes.
It will involve volunteers wearing skull caps fitted with electrodes while they sleep. The researchers plan to replicate the findings in larger and more diverse populations. They will also explore possible links between dreams and other neurodegenerative diseases such as Alzheimer's.
Studies of early signs of Parkinson's have largely focused on affluent white populations. It is the second most common neurological condition in the world - behind dementia.
Drugs given to control the condition work much better when given early on in the disease rather than when it has worsened, potentially slowing down its progression. Around 145,000 people in the UK have Parkinson’s. It is caused by a loss of nerve cells in an area of the brain involved in controlling movement.
These nerve cells produce dopamine, a chemical messenger that helps to control body movement. If these become damaged or die, levels of dopamine are reduced and movements become slow and abnormal.
But symptoms often only appear when about 80 per cent of the nerve cells have been lost. Doctors diagnose the disease by studying a patient's symptoms and movement, often followed by a DaT scan — a type of brain scan which measures dopamine levels.
Getting an early diagnosis can make such a difference to quality of life and Parkinson's progression. With appropriate management, you can carry on living well and have a productive life. Parkinson's claimed the life of boxing legend Muhammad Ali. Famous sufferers include Sir Billy Connolly and Sweet Caroline singer Neil Diamond.
The findings are in EClinicalMedicine.
