Long-term effects of cognitive therapy on biological rhythms and depressive symptoms: A randomized clinical trial

Objective: To evaluate the effect of cognitive therapy on biological rhythm and depressive and anxious symptoms in a twelve-month follow-up period. In addition, correlations between the reduction of depression and anxiety symptoms and the regulation of biological rhythm were observed. Methods: This was a randomized clinical trial with young adults from 18 to 29 years of age who were diagnosed with depression. Two models of psychotherapy were used: Cognitive Behavioral Therapy (CBT) and Narrative Cognitive Therapy (NCT). Biological rhythm was assessed with the Biological Rhythm Interview of Assessment in Neuropsychiatry (BRIAN). Severity of depressive and anxious symptoms was assessed by the Hamilton Depression Rating Scale (HDRS) and the Hamilton Anxiety Rating Scale (HARS), respectively. The sample included 97 patients who were divided within the protocols of psychotherapy. Results: There was a significant reduction in depressive and anxious symptoms (p < 0.001) and an increase on regulation of biological rhythm (p < 0.05) at the twelve-month follow-up. Moreover, we showed a positive correlation between the reduction of depressive symptoms and regulation of biological rhythm (r=0.638; p < 0.001) and between the reduction of anxious symptoms and regulation of biological rhythm (r=0 438; p < 0.001). Conclusion: Both models showed that cognitive therapy was effective on the reduction of depressive and anxious symptoms and on the regulation of biological rhythm at a twelve-month follow-up evaluation. This study highlights the association between biological rhythm and symptoms of depression and anxiety. Limitation: We did not assess genetic, hormonal or neurochemical factors and we did not include patients under pharmaceutical treatment or those with severe symptomatology. (C) 2015 Elsevier B.V. All rights reserved