IQ tests as aids to diagnosis and management in early schizophrenia

Abstract

Intellectual and other more specific neurocognitive impairments in schizophrenia are important for understanding the aetiology of the condition and its likely outcome. However, these impairments are not usually considered important for supporting a diagnosis in suspected early schizophrenia. IQ testing is widely available and probably acceptable to most people likely to be experiencing the early stages of psychosis and who might be unable or unwilling to disclose details of their history and mental state or to cooperate with more comprehensive neuropsychological assessment. Although in general IQ tests have only limited diagnostic value in schizophrenia, the finding of a substantial decline in IQ score from the estimated premorbid level may be helpful in supporting a provisional diagnosis of early schizophrenia in cases without organic signs in which the clinical picture is unclear or incomplete. More important, the results of IQ tests may contribute to a better understanding of patients' impairments and assist clinical management in a number of ways, as illustrated here by three fictional case studies.