Verbal memory predicts treatment outcome in syndromal anxious depression: An iSPOT-D report

Background: Major Depressive Disorder (MDD), anxiety disorders, and high levels of anxious symptoms are associated with impaired cognitive functioning. However, little is known of how cognitive functioning is impaired in people with anxious depression. Here, we compared cognitive functioning between people with anxious depression, non-anxious depression, and healthy controls. We also tested whether anxious depression moderated the relationship between cognitive functioning and treatment outcome.

Methods: 1008 adults with MDD and 336 healthy controls completed IntegNeuro: a computerized cognitive functioning test battery. Participants were then randomised to one of three antidepressants and reassessed at 8 weeks using the 17-item Hamilton Depression Rating Scale (HRSD₁₇) and the 16-Item Quick Inventory of Depressive Symptomatology-Self-Rated for remission and response. Syndromal anxious depression was defined as MDD with a comorbid anxiety disorder. HRSD anxious depression was defined as MDD with a comorbid HRSD₁₇ anxiety/somatisation factor score ≥ 7.

Results: Syndromal anxious depression was associated with better psychomotor functioning and poorer working memory, cognitive flexibility and information processing speed compared to their non-anxious counterparts. HRSD anxious depression was associated with better psychomotor functioning compared to their non-anxious counterparts. Syndromal anxious depression moderated the relationship between verbal memory and treatment outcome. In people with syndromal anxious depression, poorer baseline verbal memory predicted poorer treatment outcome.

Limitations: As DSM-IV criteria was used, the DSM-5 anxious distress specifier characterisation of anxious depression could not be assessed CONCLUSIONS: Syndromal anxious depression is characterised by impaired executive functions and moderates the relationship between verbal memory functioning and treatment outcome.