Does comorbid subthreshold anxiety affect clinical presentation and treatment response in depression? A preliminary 12-month naturalistic study

The aim of this study was to evaluate the effects of comorbid subthreshold anxiety on the course and the treatment of Depressive Disorders. The sample studied comprised four groups defined by the DSM-IV Axis I diagnosis: (1) Patients with a Major Depressive Disorder (MDD) and an Anxiety Disorder (DA); (2) patients with MDD and a subthreshold Anxiety Disorder (Da); (3) patients with subthreshold depression and an Anxiety Disorder (dA); (4) patients with subthreshold depression and subthreshold anxiety (da). HAMD, HAMA and CGI rating scales were administered monthly for 12 months while patients were treated with different antidepressants. Significant differences were found among the four groups with respect to the baseline depressive symptoms: Da presented more frequently suicidal ideation (x(2)=9.568, d.f.=3, p=0.023), psychomotor retardation (x(2)=12.568, d.f.=3, p=0.006), sexual dysfunctions (x(2)=7.761, d.f.-3, p=0.05), hypochondriacal ideation (x(2)=13.633, d.f.=3, p=0.003), weight loss (x(2)=9.520, d.f.=3, p=0.023), and diurnal variation of symptoms (x(2)=13.258, d.f.=3, p=0.004). With respect to the treatment response Da patients showed an overall worse response to antidepressants, having a longer latency and a lower reduction of symptoms. These results suggest that patients with Major Depression and subthreshold anxiety present with a more severe baseline clinical picture and seem to have a less efficient response to antidepressants.