Individuals diagnosed with narcolepsy have substantially higher rates of psychiatric and medical conditions than the general population, a new study shows.

“We found that 27% of persons with narcolepsy had a mood disorder, 37% were taking an antidepressant — 3 times higher than the general population — and anxiety disorders were also prevalent,” said Maurice M. Ohayon, MD, DSc, PhD, professor of psychiatry and behavioral sciences at Stanford University School of Medicine, and director of the Stanford University Sleep Epidemiology Research Center in California.

In addition, chronic medical conditions were also greatly increased, said Dr. Ohayon, who noted, “Individuals affected with narcolepsy represent a vulnerable segment of the population. However, we only have a partial understanding of this vulnerability.”

The high prevalence of both medical conditions and psychiatric disorders seen in association with narcolepsy needs to be addressed when developing a treatment plan, Dr. Ohayon concluded.

He presented the findings at the American Neurological Association (ANA) 2013 Annual Meeting here. They were also recently publishedin Sleep Medicine.

High Frequency of Psychiatric Conditions

The study examined psychiatric disorders and medical conditions associated with narcolepsy in 320 narcoleptic patients, who were compared with a sample of 1464 persons matched for age, sex, and body mass index.

Study participants were interviewed regarding sleep habits, health, medication, medical conditions, sleep disorders, and mental disorders using the Sleep-EVAL. Mental disorders were classified according to theDiagnostic and Statistical Manual, 4th edition.

A high proportion of narcoleptic patients reported psychiatric disorders, especially major depressive disorder and social anxiety disorder, which affected nearly 20% of these individuals, Dr. Ohayon reported.

Table. Proportion of Mental Disorders in Narcoleptics vs Matched Controls

Five medical diseases were also more frequently observed among narcoleptic participants: hypercholesterolemia, digestive diseases, heart disease, upper respiratory tract disease, and hypertension. The highest odds ratios were for diseases of the digestive system, which were noted in 16.3% of the narcoleptic population vs 5.0% of the controls, a 3-times-increased risk (P < 0.001), and for upper respiratory tract diseases, which were noted for 27.5% and 10.9%, respectively, for an odds ratio of 2.5 (P < 0.001).

“In addition, 34% of narcoleptics were obese, and this was with matching for body mass index in the study, and they are more likely to have hypercholesterolemia and hypertension than the general population,” Dr. Ohayon added.

He said that major depressive disorder mostly developed after the onset of narcolepsy (88%), while social anxiety was present before the onset of narcolepsy in about half the cases. He further noted that several comorbid conditions were autoimmune disorders, such as inflammatory bowel disease, asthma, and allergies.

Dr. Ohayon concluded, “We don’t know how to interpret these data. These are just facts, but we don’t know what they mean.”

Session moderator Louis Ptacek, MD, Howard Hughes Investigator in the Department of Neurology at the University of California, San Francisco School of Medicine, commented on the study for Medscape Medical News.

“The study is quite fascinating, given the statistical significance of the findings,” Dr. Ptacek said. “It’s not surprising that people who might be predisposed to psychiatric disorders could have these precipitated by a stressful event such as narcolepsy, though in some patients the psychiatric diagnosis preceded the narcolepsy. While it’s important to identify these comorbidities, we don’t yet understand the connection or causality yet, as the author pointed out.”

Source: Medscape.com