Table 3.

Common Psychiatric Symptoms or Disorders in Narcolepsy

Symptom or Disorder	Comments
Anxiety3,12,42,85,87,93	Studies show a striking presence of anxiety symptoms or even disorders, with generalized anxiety being the most studied. The unpredictability and uncontrollability of symptoms such as EDS or cataplexy can make people develop social anxieties and specific phobias may arise from the frightening character hallucinations can have. Diagnosis of an anxiety disorder often precedes the diagnosis of narcolepsy. It is suggested that the undiagnosed symptoms of narcolepsy cause high levels of anxiety which might even further delay diagnosis.
Mood disorders3,12,85,86,91–96	Mood symptoms or disorders are frequently reported by narcolepsy patients. Studies have indicated that 30–50% of patients were diagnosed with a mood disorder before the diagnosis of narcolepsy. Given the overlap in symptoms and treatment, a diagnosis of narcolepsy could be easily overseen.
ADHD33,42,94,97–99	ADHD is a frequent comorbidity in narcolepsy, both in children as in adults. Pediatric narcolepsy is characterized by hyperactivity, irritability, emotional dysregulation, aggression, distractibility, impulsiveness, and restlessness. These behaviors may be a reflection of the child’s external response to an internal feeling of sleepiness or an attempt to resist it by engaging in self-stimulatory behavior. This clear overlap between narcolepsy and ADHD symptomatology increases the risk of misdiagnosis. However, also in the adult population, an overlap of symptoms between narcolepsy and ADHD is present, which could lead to diagnostic confusion.
Autism/ disrupted social interaction90,100,101	Studies on social functioning or the occurrence of autism symptoms are scarce. However, there is growing evidence for impaired social functioning in children with narcolepsy. Some studies describe a so-called ‘narcoleptic personality’, which includes introversion, impaired affectivity modulation, irritability, and poor attention and overlaps with the clinical features of an autism spectrum disorder.
Eating disorders88,89	Changes in eating patterns with ‘carbo craving’, binge eating tendency, and nocturnal eating are very prevalent in narcolepsy. In one study, it was even found that almost 25% of narcolepsy type 1 patients fulfilled the criteria for a clinical eating disorder.
Suicidality85,86,102–104	Several studies show an increased risk of suicide in patients with narcolepsy, but the underlying relationship is complex. Sleep disturbances and EDS have been shown to be risk factors for suicide and lower levels of cerebrospinal fluid (CSF) hypocretin have been observed in depressed patients with suicidal behavior. It should be noted that suicidal ideations have been reported as a medication side effect.
Chronic pain105,106	Chronic pain is significantly more common and disabling in patients with narcolepsy type 1 and narcolepsy type 2. Although it is suggested the hypothalamic dysfunction plays a role in the high prevalence of chronic pain in narcolepsy, depression could also possibly influence pain perception.