0654 Longitudinal Symptoms of Idiopathic Hypersomnia in the Hypersomnia Foundation Registry

Abstract Introduction Idiopathic hypersomnia (IH) is a chronic neurologic disorder characterized by excessive daytime sleepiness; difficulty awakening, long sleep durations, and cognitive symptoms are variably present. Although spontaneous remission has been reported, little is known about IH’s natural history. We characterized longitudinal changes in a large registry of people with IH. Methods Data were collected via the Hypersomnia Foundation's registry at CoRDS from 6/2016 through 8/2023. Participants were considered to have IH if they selected IH from a dropdown diagnosis menu, had a current diagnosis of IH or were told by a doctor that IH explained their symptoms, and reported at least 7 hours sleep/night. Participants who met these criteria and completed the questionnaire at least twice over at least 6 months were included in analyses. Responses from each participant’s earliest and latest entries were compared, via paired t-test for continuous variables and McNemar test for categorical. Results Three hundred twenty-three participants with IH (mean age 35.0 +/-SD 12.2; 86.5% women) had an average time between first and last response of 2.4 (+/-1.4) years. Most participants (79.5%) were on IH medications at both timepoints; 5.6% started and 6.5% stopped IH treatment between timepoints. The most used medications at both timepoints were modafinil (21.7%), amphetamine-dextroamphetamine (19.8%), methylphenidate (17.7%), and armodafinil (13.6%). The only medication for which there was a significant usage change over time was modafinil, decreasing from 33.0% to 25.1%, p = 0.0005. Between the two time points, there was no change in proportion endorsing daily excessive sleepiness, long sleep durations, intentional or unintentional naps, requiring multiple alarms, or brain fog, but there was slight improvement in difficulty awakening (78.7% to 73.0%, p=0.01) and slight worsening of automatic behaviors (9.9% to 12.8%, p = 0.05). The most endorsed daily symptoms at final assessment were difficulty awakening (73.0%), excessive sleepiness (61.8%), requiring multiple alarms (55.3%), brain fog (48.4%), and poor memory (43.4%). Conclusion Over 2½ years, symptoms of IH remained largely stable. While this may suggest a lack of progression over time, the high proportion of residual symptoms also suggests a failure of current treatments to achieve comprehensive symptom control. Support (if any) NS111280