Overlapping cognitive patterns in schizophrenia and methamphetamine dependence.

Objective: To examine whether overlapping cognitive deficits exist in currently drug-abstinent chronic methamphetamine (MA) abusers and schizophrenia (SZ) patients.

Background: Both SZ and chronic MA abuse are associated with frontostriatal disruption as well as deficits in cognitive control, such as selective attention. To identify overlapping cognitive profiles, we compared performance of the 2 groups on the Stroop attention task.

Methods: Data were analyzed from 69 MA abusers who had been MA-abstinent for differing periods of time and from 23 SZ patients and 38 non-substance-abusing controls.

Results: The MA abusers in early abstinence displayed more Stroop interference than the SZ patients (P=0.004), long-term abstinent MA abusers (P=0.009), and controls (P=0.002). In the MA abusers, the magnitude of Stroop interference correlated positively with longer drug use (P=0.01) and negatively with longer drug abstinence (P=0.04). No correlations were found between psychotic symptoms and task performance.

Conclusions: On this task of attentional selection, only the MA abusers in early stages of abstinence showed performance deficits compared with controls. More research is needed to further elucidate overlapping patterns between MA abuse and SZ.