Do people with iRBD biomarkers have more cognitive symptoms than healthy controls?

People with isolated rapid eye movement sleep behavior disorder (iRBD) who test positive for specific biomarkers, such as alpha-synuclein in spinal fluid, generally have more cognitive problems than healthy people. Research shows these individuals score lower on cognitive tests and are more likely to have mild cognitive impairment even before a full dementia diagnosis is made.

What the research says

A study of 197 people with iRBD who had positive biomarkers found they performed worse cognitively than 136 healthy controls. The difference was large enough to be statistically significant, with an effect size of 0.41 on a cognitive summary score. These participants also had higher rates of mild cognitive impairment and other neuropsychiatric symptoms compared to the healthy group ¹.

Another study looked at specific brain patterns in 48 people with iRBD. It found that those who later developed dementia had specific changes in brain shape that combined with cognitive and motor issues. This pattern predicted conversion to dementia with Lewy bodies specifically, not just Parkinson's disease ⁵.

A third study examined 202 people with iRBD and 46 healthy controls using a test for pareidolias, which is a tendency to see faces in random patterns. The iRBD group showed significantly lower cognitive function than controls. Within the iRBD group, those with these visual distortions had even lower cognitive scores than those without them ⁶.

What to ask your doctor

• Do I have any early signs of cognitive decline like trouble with memory or attention?
• What biomarker tests are available to check for alpha-synuclein in my spinal fluid?
• How can we monitor my cognitive function over time to catch changes early?
• Are there lifestyle changes that might help protect my brain health given my sleep disorder?