An Investigation Into Response Inhibition in Distinct Clinical Groups Within Obsessive-Compulsive Disorder.

OBJECTIVE: Response inhibition has been frequently studied in obsessive-compulsive disorder (OCD) with mixed results. The inconsistent findings may stem in part from failure to consider the heterogeneity of the disorder. METHODS: The authors examined behavioral and event-related potential (ERP) components (N2 and P3) during a simple response inhibition go/nogo task in a sample of patients with OCD (N=48) and control subjects (N=53). Comparisons in behavioral and electrophysiological measures were made between groups (OCD compared with control) and within the OCD group in terms of symptom clusters (symmetry, forbidden thoughts, and cleaning) and comorbidity status (OCD only and OCD with depression). RESULTS: In the OCD group, the N2 component appeared more frontally localized compared with the control group. Participants with OCD demonstrated longer N2 latency and a larger difference in N2 between the nogo and go conditions, suggesting slower but greater conflict monitoring. P3 had a larger amplitude in the OCD group compared with the control group, indicative of greater response inhibition, but was also reduced in the nogo compared with go condition, suggesting suppressed response inhibition. No significant differences were found between symptom clusters, but patients with OCD only made more omission errors compared with patients with OCD and comorbid depression. The latter cohort also had faster P3 latencies, which, combined with the behavioral data, indicates slightly improved response inhibition when comorbid depression is found. CONCLUSIONS: On the basis of these results, it would seem unlikely that symptom clusters have contributed to previous inconsistencies in the literature. Comorbid depression, which may have affected previous results, should be considered in future research.

Memory rehabilitation and brain training for surgical temporal lobe epilepsy patients: a preliminary report.

The short term impact of a memory rehabilitation programme on verbal memory test performance and subjective ratings of memory in everyday life was assessed in healthy controls and left temporal lobe epilepsy (LTLE) surgical patients. The intervention involved training in the use of external and internal memory support strategies. Half of the sample in addition undertook computerised brain training exercises as homework. LTLE patients were seen either before surgery or 3-6 months after their operation. Improvements in verbal memory were observed in both groups. An effect of brain training was recorded but this did not occur in a consistent direction. Subjective ratings of memory indicated improvements that were significant for the LTLE group but not the controls. Positive changes in the memory outcome measures were associated with improvements in mood. Pre-operative memory rehabilitation was not associated with better outcomes than post-operative intervention. Further research is needed to explore the persistence of the changes observed and to explore if pre-operative rehabilitation offsets post-operative memory decline.