Isolated REM Sleep Behavior Disorder: Depression May Beget Cognitive Dysfunction

In patients with isolated rapid eye movement (REM) sleep behavior disorder (iRBD), it is crucial to monitor depressive symptoms as they may exacerbate cognitive dysfunction and elevate the risk for conversion to neurodegenerative disease, according to study results presented at the SLEEP 2024 Annual Meeting, held in Houston, Texas, from June 1 to 5, 2024.

Researchers conducted a 9-year longitudinal observational study to examine cognitive performance and quantified electroencephalography data in patients with iRBD based on the presence of depression, as well as assess how depression may impact conversion to neurodegenerative diseases.

Patients with iRBD were included in this study. A diagnosis of depression was made based on a patient taking antidepressant medication or initial interview results. The outcome of interest was the conversion to Parkinson disease (PD) or dementia.

A total of 90 patients with iRBD were included in the final analysis, 21 of whom converted to PD or dementia. Depression was identified in 27 of the 90 patients.

Individuals with depression vs those without demonstrated significantly poorer executive function (P =.029) and had lower z-scores in global cognition, attention, memory, and frontal/executive domains.

The quantified electroencephalography results indicated significantly elevated relative gamma power in the temporal (P =.049) and parietal (P =.032) regions, as well as increased high gamma power in the parietal region (P =.008) among individuals with depression vs those without.

Conversion to neurodegenerative diseases was significantly increased among patients with depression vs without depression (P =.013). Depression was associated with the risk for conversion to neurodegenerative diseases (hazard ratio, 3.319; P =.011).

“Depressive symptoms in iRBD patients should be monitored as aggravating cognitive dysfunction and a risk factor for conversion,” the researchers concluded.