Stability and Course of Neuropsychological Deficits in Schizophrenia

TLDR

Neuropsychological deficits in schizophrenia arise before clinical symptoms and intensify at onset, yet it is unclear whether they progress further over time. This study aimed to determine whether any subgroup of schizophrenia patients exhibits progressive neuropsychological decline by comparing longitudinal stability between outpatients and normal controls. Researchers administered comprehensive neuropsychological batteries annually to 142 outpatients and 206 controls over an average of three years, using test‑retest norms and subgroup analyses to detect abnormal worsening. Results showed that although patients were more impaired than controls, their neuropsychological performance remained stable over both short and long follow‑ups, with no subgroup differences or evidence of progression, suggesting stability of deficits in ambulatory schizophrenia.

Abstract

<h3>Background</h3> Neuropsychological deficits in schizophrenia appear to predate clinical symptoms of the disease and become more pronounced at illness onset, but controversy exists about whether and when further neuropsychological progression may occur. <h3>Objective</h3> To identify and characterize any subset of patients who evidenced progressive neuropsychological impairment, we compared the longitudinal stability of neuropsychological functioning in schizophrenic outpatients and normal comparison subjects. <h3>Methods</h3> One hundred forty-two schizophrenic outpatients and 206 normal comparison subjects were given annually scheduled comprehensive neuropsychological evaluations during an average of 3 years (range, 6 months to 10 years). Clinically and demographically defined subgroups were compared, and test-retest norms were used to identify individual patients who showed unusual worsening over time. <h3>Results</h3> The schizophrenic group was neuropsychologically more impaired than the normal comparison subjects but showed comparable test-retest reliability and comparable neuropsychological stability over both short (mean, 1.6 years) and long (mean, 5 years) follow-up periods. No significant differences in neuropsychological change were found between schizophrenic subgroups defined by current age, age at onset of illness, baseline level of neuropsychological impairment, improvement or worsening of clinical symptoms, and occurrence of incident tardive dyskinesia. Norms for change also failed to show neuropsychological progression in individuals with schizophrenia. <h3>Conclusions</h3> Neuropsychological impairment in ambulatory persons with schizophrenia appears to remain stable, regardless of baseline characteristics and changes in clinical state. Our results may not be generalizable to the minority of institutionalized poor-outcome patients.