Neuropsychological impairments in neuroleptic-responder vs. -nonresponder schizophrenic patients and healthy volunteers

Phencyclidine exacerbates attentional deficits in a neurodevelopmental rat model of schizophrenia

Schizophrenia is characterized by severe abnormalities in cognition, including disordered attention. In the rat, neonatal ventral hippocampal (NVH) lesions induce behavioral abnormalities at adulthood thought to simulate some aspects of the symptomatology of schizophrenia. Here, we compared the effects of NVH and adult ventral hippocampal (AVH) lesions on attentional performance as assessed by the five-choice serial reaction time task (5-CSRTT). NVH-lesioned rats were slower to acquire the task than AVH-lesioned and control animals. When training was complete, NVH- and AVH-lesioned animals exhibited stable but disrupted performance under standard conditions, thus emphasizing an implication of VH in visual attentional processes. Variations in task parameters induced a significantly greater disruption in NVH- and AVH-lesioned groups as compared to controls. NVH-lesioned rats were also hyper-responsive to the disruptive effects of a high dose of phencyclidine (PCP) (3 mg/kg). In contrast, amphetamine (0.4-0.8 mg/kg) had a similar effect in control and VH-lesioned rats. Thus, NVH-lesioned rats were impaired in the acquisition of stable performance in the 5-CSRTT, and were hypersensitive to the cognitive-impairing effects of PCP.

Schizophrenia and memory impairment: evidence for a neurocognitive subtype

Evidence is presented that verbal memory impairment distinguishes a subgroup of patients with schizophrenia who also differ in symptom profile and illness adjustment. On the basis of the California Verbal Learning Test (CVLT), a sample of patients was partitioned into memory-impaired (n=16) and memory-unimpaired groups (n=16). Groups were matched for age, sex, IQ, and anti-psychotic medication. These groups were then compared using the Brief Psychiatric Rating Scale (BPRS) and the Sickness Impact Profile (SIP). Results indicate that memory-impaired schizophrenia patients experience significantly more positive symptoms and a poorer quality of life than their memory-unimpaired counterparts. This finding supports the idea that neurocognitive measures are a valuable way of organizing the heterogeneous disease states of schizophrenia.