Why lashing out in your sleep may be a sign you'll develop DEMENTIA or Parkinson's within the next 15 years

The earliest signs of dementia and Parkinson's disease could lie in the content of your nightmares, a leading neuroscientist has revealed.

According to eminent brain health expert Dr Rahul Jandial, dreaming of violent or threatening scenes - like being chased, killed or running away from a menace - could indicate early brain decay seen in a host of neurological conditions.

Those at highest risk are people whose disturbing dreams cause them to physically act out while they sleep - like punching, kicking and even strangling one's partner.

For instance, a staggering 97 percent of people who exhibit these behaviors while sleeping will go on to develop Parkinson's or another neurological condition within 14 years, studies show.

Acting out dreams, which can include running from a threat, clapping or singing, or throwing punches, is often a harbinger for brain disorders

In cases where the cause of REM behavior disorder is unknown, 97 percent of people who have it will be diagnosed with a brain disorder within about 14 years

Experts have coined the problem of these types of nightmares, which often cause physical action, REM behavior disorder - which is believed to affect about 0.5 to 1.25 percent of the general population, up to about 4.2 million people.

In Dr Jandial’s new book, This Is Why You Dream, he investigates the meaning and benefits of dreaming. 

He describes a 55-year-old male patient at the Los Angeles VA hospital who sought his help with new-onset nightmares.

He had begun acting them out, screaming in his sleep, even striking his roommate in the face.

Dr Jandial said: ‘We didn’t know it then but this unique combination of symptoms – men in their fifties acting out their dreams – years later develop a type of brain disease called synucleinopathies. Not just sometimes, but almost always.’

Dr Jandial's new book explains why we dream about certain individuals and what our dreams mean for our health

Synucleinopathies is an umbrella term for diseases like Parkinson's and some dementias, which are characterized by a build-up of a protein in the brain called alpha-synuclein.

This compound is involved in the regulation of hormones in neural regions. 

In synucleinopathies including Parkinson's, Lewy body dementia - which causes changes in perosnality - and a little-known condition called multiple system atrophy, the protein builds up and forms clumps that can disrupt normal cell functioning and lead to brain cell damage.

Exactly how those clumps lead to dream enactment behavior is not known. But its ability to predict synucleinopathies is uncanny. 

These disorders, on average, show up within 10 to 15 years after the onset of the dream behavior disorder.

People with REM behavior disorder often have vivid, violent dreams involving an imminent physical threat to themselves or someone they love. 

Case studies have described people becoming violent - punching, kicking, and  wrestling their partners, and running in their sleep to escape the dream assailant.

The behavior isn’t always violent, though. People with this disorder have reported singing or clapping in their sleep and even enacting peaceful activities like fishing.

Daniella Berg, a neurologist at the University Hospital Schleswig-Holstein in Germany, told Scientific American that among the early clues for Parkinson's, ‘RBD is special.

‘It's the strongest clinical prodromal marker we have.’

Prodromal in medicine typically refers to early symptoms of a disorder that appear well before more advanced and specific signs of diseases do. 

Since meeting with that patient at the VA, Dr Jandial has seen several more patients like him with the sleep disorder, which led to neurological diagnoses.

Actor Alan Alda, who starred in the television series M*A*S*H, revealed that unusual dreams helped lead him to his Parkinson's diagnosis. 

Actor Alan Alda was diagnosed with Parkinson's in 2018. A major clue for him was his violent dream enactment behavior. Alda knew this could be an early symptom, and asked his doctor for a test

The link between dream enactment behavior and Parkinson's is still unfolding, but Mr Alda had read an article about it in 2015 that prompted his doctor to test him for the brain disorder out of caution. 

Mr Alda said in 2018: 'By acting out your dreams, I mean I was having a dream where someone was attacking me and I threw a sack of potatoes at them, and what I was really doing was throwing a pillow at my wife. 

'The doctor said, "Why do you want a scan? You don't have any symptoms"... And I said, I want to know if there's anything I can do — I want to do it."' 

RBD and Parkinson's disease are both linked with dysfunction in the brainstem, which is instrumental in regulating sleep and movement. 

What your most terrifying nightmares REALLY mean 

They usually involve a threat to our survival, security or self-esteem, and they fill us full of dread. They can also produce intense feelings of fear, anger, sadness, confusion and even disgust. Nightmares also force us to vividly recall the frightening events. 

Dr Jandial said: ‘Because acting out dreams and the new onset of nightmares are clinical harbingers of Parkinson’s, arriving years, even decades, before the first movement symptoms of the neurodegenerative condition, paying attention to dreams and dreaming could offer physicians a rare window for truly early intervention.’

Severe nightmares are common in the late stages of the disease. 

Nearly 80 percent of patients with Parkinson’s suffer from terrible nightmares.

Neurological disorders are not the only types of disorders that can be predicted by REM behavior disorder. 

In a study of heart patients, the types of dreams people had suggested how well they were recuperating after a routine procedure to open up narrowed arteries.

Researchers followed the patients for six months after they were discharged from the hospital, and scored them on a six-point scale: cured, improved, unchanged, worse without rehospitalization, worse with rehospitalization, worse without hospitalization, and death.

‘Men dreaming of death and women dreaming of separation were significantly more likely to have experienced worse clinical outcomes, independent of the severity of their heart disease initially. 

'This suggests that dreams somehow offered a clue into their prognosis.’