Background: Earlier findings suggest both a link between sleep and memory consolidation and a relationship between abnormal sleep at baseline and poor treatment outcome in major depression after interpersonal psychotherapy (IPT).
Methods: Pre-treatment polysomnography was examined in 32 patients with a major depressive episode (mean age = 39.5 years, 20 women). Declarative memory was tested by the Rey-Osterrieth Complex Figure Test and a paired associative word list and procedural learning was assessed by a mirror tracing skill. All patients were treated with IPT according to the manual and did not receive any antidepressant medication. Twenty-three patients took part in a minimum of 12 sessions of IPT. Remission was defined as 2 consecutive weeks with a score <8 on the Hamilton Rating Scale of Depression.
Results: Declarative visual memory performance was associated with total sleep time and total amount of rapid eye movement sleep. In IPT remitters (n = 14), there was a trend towards a decrease in rapid eye movement density (first period) and a significant decrease in delta power in pre-treatment sleep in comparison to non-remitters (n = 9). Treatment outcome after IPT was also associated with declarative memory performance at baseline (as a trend).
Conclusions: Further indications of a role of sleep in memory processes and of the importance of specific sleep parameters as markers for a positive treatment response to psychotherapy were found.