Larger hypothalamic volume in narcolepsy type 1.

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Abstract

Narcolepsy type 1 is a neurological sleep disorder. Post-mortem studies have shown 75-90% loss of the 50,000-70,000 hypocretin-producing neurons and 64-94% increase in the 64,000-120,000 histaminergic neurons and conflicting indications of gliosis in the hypothalamus of narcolepsy type 1 patients. The aim of this study was to to compare MRI-based volume of the hypothalamus in narcolepsy type 1 patients and controls in vivo.We used a segmentation tool based on deep learning included in Freesurfer and computed the volume of the whole hypothalamus, left/right part of the hypothalamus and 10 hypothalamic subregions. We included 54 post-H1N1 narcolepsy type 1 patients (39 females, mean age 21.8 ± 11.0 years) and 114 controls (77 females, mean age 23.2 ± 9.0 years). Group differences were tested with general linear models using permutation testing in Permutation Analysis of Linear Models and evaluated after 10,000 permutations, yielding two-tailed p-values. Furthermore, a stepwise Bonferroni correction was performed after dividing hypothalamus into smaller regions.The analysis revealed larger volume for patients compared to controls for the whole hypothalamus (Cohen’s d=0.71, p=0.0028) and for the left (d=0.70, p=0.0037) and right part of the hypothalamus (d=0.65, p=0.0075) and left (d=0.72, p=0.0036) and right tubular-inferior (d=0.71, p=0.0037) hypothalamic subregions.In conclusion, post-H1N1 narcolepsy type 1 patients showed significantly larger hypothalamic volume than controls, in particular in the tubular-inferior subregions which could reflect several processes as previous studies have indicated neuroinflammation, gliosis and changes in the numbers of different cell types.© The Author(s) 2023. Published by Oxford University Press on behalf of Sleep Research Society.