Chronic haloperidol treatment does not affect structure of attention in schizophrenia

Results of a number of investigations indicate attention is a multifactorial construct composed of four distinct cognitive factors including focus-execute, sustain, encode and shift abilities. While investigators have partially or fully replicated this attentional structure in a number of clinical and nonclinical populations, no study has adequately examined the structure of attention in patients with schizophrenia who are not treated with antipsychotics. In this study, we examined the four-factor theory of attention in patients with schizophrenia while they were stabilized on haloperidol (with no adjunctive antiparkinsonian/anticholinergic medications) and again when they were approximately 3 weeks drug free. Standard neuropsychological measures were used to assess attentional functions. Principal components analyses (varimax rotation) of neuropsychological test scores in medicated and drug-free conditions indicated that four factors accounted for 84.2 and 91.8 of total variance in medicated and unmedicated conditions, respectively. Based on these results, it appears that: (1) haloperidol does not appreciably affect structure of the attentional system in patients with schizophrenia; (2) unmedicated patients with schizophrenia exhibit a similar structure of attention as both medicated patients and controls, suggesting that attentional structure is 'normal' in schizophrenia; and (3) the four-factor attention theory is a useful and valid paradigm for evaluating attention in patients with schizophrenia, regardless of medication status.