1. Home>
2. Specialties>
3. Psychiatry>
4. Summary and Comment

Neurobiology and Response to Psychotherapy

Previous studies have shown that both major depressive disorder and obsessive compulsive disorder (OCD) are associated with specific alterations in neurobiology. Two new studies suggest different interactions between neurobiology and psychological treatment for depression and OCD.

The first study examined 90 outpatients with major depressive episodes (unipolar, nonpsychotic, without comorbid diagnoses) who were treated with cognitive behavior therapy (CBT) for 16 weeks; 72 of these patients with full or partial remission after the acute treatment were followed for another three years. Patients with sleep abnormalities (in REM latency and density, and sleep efficiency) were less likely to remit, were slower to remit, and were more likely to have recurrences after CBT than patients with normal sleep profiles. Patients with more severe depression were also less likely to experience remission and more likely to relapse than patients with less severe depression, although there was no additional interaction between depression severity and sleep abnormalities.

The second study examined nine patients with OCD before and after ten weeks of exposure-and-response prevention (ERP) with cognitive restructuring. PET scans revealed that metabolic activity of the right caudate nucleus diminished back toward normal in ERP responders. Nonresponders showed an increase in metabolic activity that is usually associated with OCD. When these results were combined with data from a previous study of nine other OCD patients treated with ERP, the analysis showed a significantly greater reduction in right caudate metabolic activity in ERP responders than nonresponders, as well as a significantly decreased correlation among metabolic rates of the right caudate, orbital cortex, and thalamus.

Comment: The authors of the depression study suggest that more severe depressions with greater "biological" loading (i.e., sleep abnormalities) may be associated with increased cortisol which may interfere with intellectual tasks necessary for psychotherapy. Conversely, the authors of the OCD study suggest that excess activity of the right caudate, perhaps synchronized with other systems in a "repetitive behavior circuit," interferes with the ability to acquire new patterns of nonrepetitive mental and physical behavior and that behavior therapy corrects this abnormality, releasing procedural memory for new learning.

If both groups of investigators are correct, some neurobiological abnormalities may be more amenable than others to correction by specific psychological interventions, or at least different psychotherapies, like different pharmacotherapies, may be more specific for one form of pathophysiology than another.

— S Dubovsky

Published in Journal Watch Psychiatry April 1, 1996

Citation(s):

Thase ME et al. Abnormal electroencephalographic sleep profiles in major depression. Arch Gen Psychiatry 1996 Feb 53 99-108.

• Medline abstract (Free)

Schwartz JM et al. Systematic changes in cerebral glucose metabolic rate after successful behavior modification treatment of obsessive-compulsive disorder. Arch Gen Psychiatry 1996 Feb 53 109-113.

• Medline abstract (Free)