AI Article Synopsis
- Narcolepsy type 1 (NT1) is linked to the loss of orexin-producing neurons in the hypothalamus, potentially due to an immune response, but past studies showed no inflammation during later stages of the disease.
- This research investigated microglia density in the hypothalamus and thalamus of NT1 patients using PET imaging, compared to control subjects, while also exploring relationships between microglial activity and disease factors like duration and severity.
- Results indicated no significant differences in microglial density between NT1 patients and controls in the hypothalamus and thalamus, but lower overall brain microglial activity was observed in NT1 patients, raising questions about the disease's immune mechanisms and its onset
Article Abstract
Background And Objectives: Narcolepsy type 1 (NT1) is due to the loss of hypothalamic neurons that produce orexin (ORX), by a suspected immune-mediated process. Rare postmortem studies are available and failed to detect any inflammation in the hypothalamic region, but these brains were collected years after the first symptoms. In vivo studies close to disease onset are lacking. We aimed to explore microglia density in the hypothalamus and thalamus in NT1 compared with controls using [F]DPA-714 PET and to study in NT1 the relationships between microglia density in the hypothalamus and in other regions of interest (ROIs) with disease duration, severity, and ORX levels.
Methods: Patients with NT1 and controls underwent a standardized clinical evaluation and [F]DPA-714 PET imaging using a radiolabeled ligand specific to the 18 kDa translocator protein (TSPO). TSPO genotyping determined receptor affinity. Images were processed on peripheral module interface using standard uptake value (SUV) on ROIs: hypothalamus, thalamus, frontal area, cerebellum, and the whole brain. SUV ratios (SUVr) were calculated by normalizing SUV with cerebellum uptake.
Results: A total of 41 patients with NT1 (21 adults, 20 children, 10 with recent disease onset <1 year) and 35 controls were included, with no significant difference between groups for [F]DPA-714 binding (SUV/SUVr) in the hypothalamus and thalamus. Unexpectedly, significantly lower SUVr in the whole brain was found in NT1 compared with controls (0.97 ± 0.06 vs 1.08 ± 0.22, = 0.04). The same finding between NT1 and controls in the whole brain was observed in those with high or mixed TSPO affinity ( = 0.03 and = 0.04). Similar trend was observed in the frontal area in NT1 (0.96 ± 0.09 vs 1.09 ± 0.25, = 0.05). In NT1, no association was found between SUVr in different ROIs and age, disease duration, severity, or ORX levels.
Discussion: We found no evidence of in vivo increased microglia density in NT1 compared with controls, even close to disease onset, and even unexpectedly a decrease in the whole brain of these patients. These findings do not support the presence of neuroinflammation in the destruction process of ORX neurons.
Trial Registration Information: ClinicalTrials.org NCT03754348.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1212/WNL.0000000000209326 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!