Spotting neurodegeneration early can help patients get treatment before things spiral out of their own control. But the signs of neurodegenerative diseases like Alzheimer’s and Parkinson’s disease are often slowly progressing and hard to see, especially for family, friends and patients themselves who are less likely to spot small incremental changes. Recent research has shown that sleep disturbances, like insomnia, sleep apnea and drowsiness, might be warning signs for these disease. But there’s one sleep-related symptoms that are a little weirder—dreaming of animals.
One study from 2011 looked at the dream features of patients with Parkinson’s disease. Patients with Parkinson’s dreamed differently than those without. Parkinsonian dreams often involved physical aggression and animals, especially fights with animals. In fact, 17 percent of the Parkinsonian patients reported dreaming of animals, compared with just 4 percent of the control group.
Recently, scientists have started to wonder just how REM disorders are implicated in neurodegeneration. Do these disorders cause neurodegeneration? Are they a sign of them? In one study that looked at 14,600 patients, those with sleep troubles were more likely to be diagnosed with Alzheimer’s.
At Nature, Mo Costandi explains just what it would take to figure out whether the sleep troubles come first or second:
The evidence is building for a correlation between disturbed sleep and neurodegenerative diseases, but the next step — discovering whether sleep disturbances are a cause of these conditions — will take considerably more research. In particular, establishing a causal relationship will require longitudinal studies that assess the sleeping patterns of large numbers of people over long periods of time, and link specific types of sleep disorder with the incidence of each disease. But to diagnose the diseases accurately, researchers must look for the tell-tale signs in the brains of study participants.
So for now we’re stuck with a chicken and egg problem, requiring more research. Do REM disorders cause or aggravate neurodegeneration, or are they simply warning signs? And what’s up with the animal dreams?
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