Elsevier

Biological Psychiatry

Volume 59, Issue 9, 1 May 2006, Pages 863-871
Biological Psychiatry

Original article
Generalized and Specific Neurocognitive Deficits in Prodromal Schizophrenia

https://doi.org/10.1016/j.biopsych.2005.09.005Get rights and content

Background

Neurocognitive deficits are considered to be central to the pathophysiology of schizophrenia, and the neurodevelopmental model suggests that such deficits precede full-blown psychosis. The present study examined performance on a broad neuropsychological battery of young subjects considered to be at clinical high risk for schizophrenia, who were subsequently followed to determine clinical outcome.

Methods

Subjects were 38 clinical high-risk patients (58% male patients; mean age = 16.5) and 39 sex- and age-matched healthy control subjects. At baseline, all high-risk patients had attenuated (subpsychotic) schizophrenialike positive symptoms. Clinical follow-up data of at least 6 months duration was available on 33 patients, of whom 12 developed nonaffective psychotic disorders.

Results

At baseline, clinical high-risk patients had significantly impaired global cognitive performance relative to control subjects and to estimates of their own prior intellectual functioning. Measures of verbal memory and executive functioning/working memory showed significantly greater impairments; visuospatial functioning was relatively spared. Prodromal patients who later developed psychosis had significantly lower verbal memory scores at baseline compared with patients who remained nonpsychotic.

Conclusions

Verbal memory deficits may be an important risk marker for the development of schizophrenia-spectrum psychotic disorders, possibly indicating the presence of a prefrontal-hippocampal neurodevelopmental abnormality. Generalized neurocognitive impairment may be a nonspecific vulnerability marker.

Section snippets

Subjects

Clinical high-risk patients were recruited for research from referrals to the clinical arm of the Recognition and Prevention (RAP) Program (the RAP Clinic). Written, informed consent was obtained from the patient if >17 years old or from the parent (with patient’s written assent) if under 18 years. The research protocol was approved by the Institutional Review Board at North Shore-Long Island Jewish Health System (NS-LIJHS) and potential subjects were informed that treatment in the RAP Clinic

Baseline Between-Group Comparisons: Estimated Premorbid and Current IQ

Compared with CNTL, RAP patients had significantly lower estimated premorbid IQ [t(73) = 2.17, p = .033] and estimated current full-scale IQ [t(74) = 3.99, p < .001]. Deficits in current IQ remained statistically significant even after controlling for premorbid IQ and test form in ANCOVA [F(1,69) = 9.97, p = .002]. Repeated measures analysis of variance demonstrated a significant group by measure interaction [F(1,70) = 4.08, p = .047]. As shown in Figure 1, CNTL subjects showed a slight

Discussion

There are several significant findings of this study, which will be discussed in turn. First, clinical high-risk subjects showed significant deficits relative to control subjects in both estimated premorbid and current IQ. Moreover, RAP patients had lower current estimated IQ (∼1.0 SD reduction) than was predicted by premorbid estimated IQ (∼.5 SD). This pattern of deficits, identified in adolescent patients who were not yet psychotic, is consistent with a progressive neurodevelopmental model

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