Objective rest-activity cycle analysis by actigraphy identifies isolated rapid eye movement sleep behavior disorder

Area of Science:

• Neurology
• Sleep Medicine
• Biomarkers

Background:

• Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) is a prodromal stage of synucleinopathies.
• Early identification of iRBD is crucial for timely intervention.
• Current screening methods may have limitations in distinguishing iRBD from other sleep disorders.

Purpose of the Study:

• To investigate the utility of rest-activity rhythm features in differentiating iRBD patients from those with other motor sleep disorders and healthy controls.
• To assess whether actigraphy-derived metrics can serve as objective biomarkers for iRBD detection.

Main Methods:

• Nineteen iRBD patients, 39 patients with other motor sleep disorders (RLS, SAS), and 16 healthy controls underwent 2-week actigraphy and polysomnography.
• Non-parametric analyses were used to evaluate rest-activity rhythm features, including the I < O index.
• REM sleep behavior disorder screening questionnaires were also administered.

Main Results:

• iRBD patients exhibited lower sleep efficiency, increased wake after sleep onset, and more frequent prolonged activity bouts compared to RLS patients and controls.
• The I < O index effectively distinguished iRBD patients from RLS, SAS, and controls, outperforming screening questionnaires.
• An I < O value of 98.32 demonstrated optimal sensitivity (63.2%) and specificity (89.1%).

Conclusions:

• The I < O index derived from actigraphy is a valuable objective measure for screening iRBD in large populations.
• This approach can aid in identifying individuals at risk for synucleinopathies.
• Rest-activity rhythm analysis offers a promising tool for early iRBD detection.