BARCELONA – Hypersomnia is a novel, previously unappreciated factor useful in tipping the balance in favor of an underlying bipolar predisposition in patients with an acute major depressive episode, Andrea Murru, MD, PhD, reported at the annual congress of the European College of Neuropsychopharmacology.
Bruce Jancin/MDedge News
Dr. Andrea Murru
“This may help us in clinical practice. It’s an effective, costless, and highly objective clinical measure. It’s one question, and it takes a second. It’s simply asking the patient: ‘Are you sleeping more hours at night than usual?’ It’s a very simple clinical question that could really change the focus of treatment for a patient,” said Dr. Murru, a clinical psychiatrist in the bipolar disorders program of the University of Barcelona.
He presented a post hoc analysis of 2,514 acutely depressed individuals who participated in the BRIDGE-II-MIX (Bipolar Disorders: Improving Diagnosis, Guidance and Education) study, an international, multicenter, cross-sectional, observational study aimed at better characterizing clinically valid mixed features of depression indicative of concurrent manic symptoms.
“This is one of a whole series of hypothesis-generating studies from BRIDGE-II-MIX that are trying to deal with the struggle of understanding whether all the elements that favor mixicity and an underpinning bipolar diathesis are fairly represented in the diagnostic criteria in DSM-5. And what we are basically finding is the DSM-5 criteria are leaving out important symptoms that really do play a role,” the psychiatrist said in an interview.
One of those missing factors, he continued, is hypersomnia. It was present in 16.8% of the study population, and he and his coinvestigators compared them in terms of clinical variables, current and past psychiatric symptoms, and sociodemographics with the 83.2% of patients with insomnia. That is, patients who got fewer hours of sleep than normal and felt fatigued during the next day were compared with those who felt a reduced need to sleep.
The two groups differed in important ways. Hypersomnia showed a powerful correlation with a physician diagnosis of major depressive episode with atypical features, being present in 32.2% of such patients, while a mere 1.8% had insomnia. Moreover, among patients diagnosed with bipolar disorder I or II, 20.6% reported hypersomnia, a significantly higher proportion than the 16% who had insomnia.
The finding that only 5% of BRIDGE-II-MIX participants with hypersomnia met DSM-5 criteria for a mixed-state specifier, a rate not significantly different from the 8.3% figure in those with insomnia, underscores the drawbacks of the DSM-5 criteria, according to Dr. Murru. He noted that, in contrast to the DSM-5 criteria, 32.9% of the hypersomniac patients with a major depressive episode met Research Diagnostic Criteria (RDC) for a mixed-state specifier, a rate significantly higher than the 27.6% figure in patients with insomnia.
Specifically, the individual RDC mixed-state specifiers that stood out as significantly more frequent among depressed patients with hypersomnia than insomnia were racing thoughts, by a margin of 15.1% to 10.6%; impulsivity, 16.8% versus 13.2%; distractibility, 29.6% versus 23.4%; hypersexuality, which was present in 4% of patients with hypersomnia but only 2.3% with insomnia; irritable mood, 33.1% versus 24.8%; and a history of insufficient response to previous antidepressant therapy, 34.3%, compared with 27.1% in insomniacs.
When Dr. Murru and his coinvestigators performed a stepwise linear regression analysis to identify significant predictors of hypersomnia in patients with a major depressive episode, they found that the sleep abnormality keeps some interesting company. Patients with current bulimia were 4.21-fold more likely to have hypersomnia than those without the eating disorder. Current social phobia was associated with a 1.77-fold increased risk of hypersomnia; mood lability on prior antidepressant therapy carried a 1.37-fold risk, as did current mood lability; prior attempted suicide was associated with a 1.31-fold increased risk; being overweight or obese was associated with a 1.42-fold risk; currently being on a mood stabilizer carried a 1.33-fold increased risk of hypersomnia; and currently being on an atypical antipsychotic agent had a 1.36-fold greater risk.
Dr. Murru concluded that the take-home message of this study – “Of course, conceding it’s highly exploratory nature intrinsic to a post hoc analysis,” he noted – is that hypersomnia should be included among the symptoms that trigger the “with mixed features” specifier in patients with a major depressive episode.