Familial and sporadic non-rapid eye movement parasomnia in adults: clinical and sleep differences

The heritable trait of non-rapid eye movement (NREM) parasomnias is well known, but differences between sporadic and familial phenotypes have not been studied. The aim of our study was to evaluate, in a clinical series of adults with NREM parasomnias, clinical and sleep differences between familial versus sporadic forms, and between childhood versus adolescent versus adult-onset forms.

We prospectively collected clinical features, family history, questionnaires (Epworth Sleepiness Score and Paris Arousal Disorders Severity Scale (PADSS)), and video-polysomnography measures from patients with NREM parasomnias confirmed by video-polysomnography, admitted over a 12-year period. Familial NREM parasomnia was defined as having at least one relative of the index case with NREM parasomnia.

Of the 625 consecutive adults with NREM parasomnias, 50% had a family history of NREM parasomnia (most commonly parents, followed by siblings, then children). Compared to those with sporadic NREM parasomnias, participants with familial NREM parasomnias had an earlier age of onset and greater severity of NREM parasomnias (according to the PADSS). They were more likely to report sleepwalking, sleep terrors, and a combination of parasomniac manifestations (but no more confusional arousals or sleep-related eating disorders), and were less likely to report sexsomnia. In contrast, monthly episode frequency, sleepiness score, sleep structure, and EEG and behavioral markers of NREM parasomnias did not differ between groups.

Familial NREM parasomnias have a typical phenotype with an earlier age of onset and a more severe clinical course. This phenotyping may guide medical care and future genetic studies.