REM Sleep Behavior Disorder (RTSP) is a condition characterized by restlessness during the exteriorization of dreams. These turbulent dreams (transposed more or less directly into reality) would be harbingers of synucleinopathic neurodegenerative diseases, such as Parkinson’s. Although much research, including that of James Parkinson himself, seems to support this hypothesis, the true causal link is still widely debated. A new synthesis of studies today highlights new data on the close link between TCSP and Parkinson’s disease. The results seem to confirm that the detection of TCSPs can be a powerful tool for the early diagnosis of the disease.
We’ve all had at least one dream where we felt like we were being chased. This kind of dream sometimes seems so real to us that the fear is just as real, and so we quickly choose confrontation or flight. Strangely, we sometimes wake up with a start, feeling like we still have to run.
Namely, this kind of dream is very different from somnambulism or sleep language, which occur rather during deep sleep. The latter also occur more in children and adolescents, while PTSDs are more frequently reported in the elderly. TCSP can be triggered by certain medications such as antidepressants, or underlying pathologies such as narcolepsy or a brainstem tumor. But more often, they make it possible to predict at 80% the risk of synucleinopathic neurodegenerative disease (causing an accumulation of alpha-synuclein proteins), which generally appears 10 to 15 years following the appearance of a TCSP.
The first data suggesting a correlation between Parkinson’s and PTSD date from the 1800s, when James Parkinson described trembling movements of the limbs during sleep of patients, which eventually startled them awake. The TCSP would thus be valuable clues for the early diagnosis of the disease. ” It is the strongest clinical prodromal marker we have », estimated Daniela Berg, a neurologist at Schleswig-Holstein University Hospital in Germany.
Protein accumulation observed in TCSP and Parkinson’s disease
While people with Parkinson’s disease appear to have difficulty coordinating their movements, people with TCSP do not experience coordination defects while they sleep. But when these people are asleep, the “brakes” supposed to restrict movement during sleep are lifted.
Experiments in cats suggest that lesions in the brainstem (seen early in Parkinson’s disease) are the cause of this inhibition of muscle paralysis during sleep. These cats, in which brainstem lesions were induced, behaved normally when awake, but had particularly restless sleep (with behaviors opposite to those observed during wakefulness).
This difference in behavior during sleep and wakefulness would also be observed in men with TCSP. As evidence, a study dating from the 1990s observed 29 patients with TCSP, all male and aged 50 and over. 11 of them had developed a neurodegenerative disease regarding 13 years following their first TCSP. In 2013, this figure rose to 21, and was mainly associated with Parkinson’s disease.
The physiological correlation of TCSP with Parkinson’s disease lies in the accumulation of alpha-synuclein proteins (Lewy body disease). The accumulation of this protein in the brain particularly hinders motor and cognitive functions. Lewy body aggregation is seen both in autopsies of people with TCSP and those of people who have died of Parkinson’s disease. As this protein aggregation is undetectable on CT, the TCSP would thus be a good means of early diagnosis of the disease.
TCSP dreams wouldn’t necessarily be restless
Researchers have also tried to explain why people with Parkinson’s do not have motor difficulties when they dream. The results suggest that the basal ganglia (which have the role of suppressing unwanted movements), which are altered in patients, are inactive during sleep. This finding therefore suggests that in people with TSCP, movements are generated by a motor circuit that can bypass the ganglia. ” It kind of goes to show that not everything that happens in Parkinson’s when it comes to movement applies to you when you’re sleeping. explains Ronald Postuma, professor of neurology at McGill University.
Moreover, clinical observations have also demonstrated that TSCP dreams are not necessarily of an agitated nature. It would happen in particular that these people laugh or sing in their REM sleep. The researchers then hypothesized that violent or agitated dreams are more often reported because they would be more likely to wake the person or the partner. “ I am quite convinced that in TSCP patients, the window is open to dreaming, but their dreams are no different from ours. », Estimates Isabelle Arnulf, professor of neurology at the University of the Sorbonne. In addition, according to the expert, a small percentage of these people would generally not remember dreams. The incidence of synucleinopathic diseases might thus be greater than believed.
