The high prevalence of anxiety and depression in patients with narcolepsy suggests that a biological relationship is present between the disorders, but larger studies are needed.
The coexistence of the prevalence of anxiety and depression in patients with narcolepsy and the fact that these conditions precede the definitive diagnosis of narcolepsy suggests a possible biological relationship between both disorders, according to a study published in Journal of Sleep Research.
Sleep disorders are very common in the general population, but narcolepsy is considered a “rare” disease because of its low prevalence (25-50 cases per 100,000 people). It has been known that psychiatric illnesses are associated with sleep disorders, and the link between narcolepsy and psychiatric illness has been known for 50 years.
This study was conducted because interest in the link between mood disorders and narcolepsy has increased in the last 5 years, even though very few organizations have reported on it.
Due to this increase in interest, researchers were trying to understand the coexistence of anxiety and depression in patients with narcolepsy. They wondered if there could be a prior tendency to suffer from the disorders because of the relationship between the serotonergic, noradrenergic, and dopaminergic pathways present in affective disorders and narcolepsy.
A total of 51 patients with narcolepsy were included in the study (mean [SD] age, 41.10 [14.71] years), with 23 males and 28 females. Out of the total, 27 patients and 24 patients had narcolepsy with and without cataplexy, respectively. Out of 51 patients, 18 had anxiety disorder. Of those, 14 had major depression, 2 had attempted suicide, 1 had manic outbreak, and 1 had substance abuse. Out of the 18 patients with anxiety and depression, 10 had narcolepsy with cataplexy, and 8 had narcolepsy without cataplexy.
Next, a comparative analysis was used to examine the coexistence of psychopathology in patients with narcolepsy at the Multidisciplinary Sleep Unit in Madrid, Spain. Researchers performed an observational retrospective descriptive analysis of the patients that attended the sleep disorders unit from October 2012 to October 2021.
A statistically significant relationship was found between younger age and anxiety presence, with the prevalence of anxiety and depression in patients with narcolepsy as triple that of the general population, especially in younger patients (P = .004; odds ratio, 2.94; 95% CI, 1.544-4.926). Psychopathology came before the diagnosis of narcolepsy in most patients, the authors said.
In addition, hardly any differences were observed between patients who had narcolepsy with cataplexy and narcolepsy without cataplexy in terms of the prevalence of anxiety and depression (55.555% and 44.44%, respectively), so hypocretin deficiency cannot be clearly delineated as a “cause” of mood disorders.
Also, the presence of anxiety or depression was found to be similar in other studies, but the researchers emphasized that these findings were simply classified as symptoms of mood or sadness scored by validated scales that were not confirmed by a psychiatrist.
The authors went on to say, “According to our daily experience, symptoms of anxiety and depression appear previous or parallel to the onset of symptoms of excessive daytime sleepiness and episodes suggestive of cataplexy. The problem in both cases is that until a neurologist makes the definitive diagnosis of narcolepsy, and a psychiatrist makes the definitive diagnosis of anxiety or depression, there may be years of difference.”
Next, they highlighted that the coexistence of narcolepsy and psychopathology limits the use of several drugs commonly used to treat narcolepsy.
Additionally, almost all participants already presented psychopathology symptoms before a narcolepsy diagnosis, so there may have been other factors in the areas of family, work, or personal life that conditioned the problem and aren’t directly related to narcolepsy, although it could be a promoter.
The researchers concluded by recommending larger studies to further explore this topic.
Abenza-Abildua MJ, Suárez-Gisbert E, Lores-Gutiérrez V, et al. Anxiety and depression in patients with narcolepsy. J Sleep Res. Published online December 23, 2022. doi:10.1111/jsr.13812