An average of 21.9% of patients with major affective disorders (bipolar disorder and major depressive disorder) show mixed features, i.e. dysphoric hypomania or agitated-irritable depression in an index episode, which made them significantly more likely to exhibit suicidal behavior, substance abuse, and to change diagnoses from depression to bipolar disorder, according to a study published in Acta Psychiatrica Scandinavica.
Study participants (N=3099) were adult outpatients being treated at the Lucio Bini Mood Disorder Centers in Rome or Cagliari, Italy. All patients had a primary diagnosis that met the DSM-5 criteria for major depressive disorder (n=1921) or bipolar disorder (n=1178, 521 bipolar I and 657 bipolar II), were treated prospectively for an average of 5.61 years (5.25-5.97), and provided informed, written consent for aggregate and anonymous reporting of their clinical data. To qualify as having mixed features, patients had to show presence of anguish, prominent mood-liability, irritability, or dysphoria in hypomania; or irritability, affective liability, agitation, pressured speech or crowded thoughts, with lack of psychomotor retardation during depressive episodes.
There were 679 mixed feature patients out of the total 3099 (21.9%). When patients with mixed features were compared with the 2420 patients without mixed features, data showed that mixed features were slightly more common in women than men (23.1% and 19.6%, respectively), were younger at illness-onset (29.5 vs 33.5) and at intake (42.2 years vs 43.8 years), and had more total illness years (16.2 vs 13.1). They were also more likely to be unemployed, to be separated or divorced, and to have fewer children. When categorized by individual diagnosis, 35.8% of patients with bipolar II showed mixed features compared with 23.2% of patients with bipolar I, and 16.8% of patients with major depressive disorder. They were also more likely to exhibit suicidal behavior (8.06% vs 5.45%), substance abuse (21.1% vs 5.93%), and to have a family history of bipolar disorder (27.8% vs 18.6%).
Study investigators conclude, “[mood] disorders with mixed features in depression or [hypo]mania appear to represent distinct and prevalent clinical subtypes with prognostic and therapeutic significance. They require further study of their longitudinal stability and to assess responses to specific treatments.”
Tondo L, Vázquez GH, Pinna M, Vaccotto PA, Baldessarini RJ. Characteristics of depressive and bipolar disorder patients with mixed features [published online June 3, 2018]. Acta Psychiatr Scand. doi: 10.1111/acps.12911