The Stability of Intellectual Function in Chronic Schizophrenia

Consistent performance over time of schizophrenic patients on a neuropsychological set of tests

“…The results of the present study is accordant with an earlier study examining the general intelligence in schizophrenic patients, with a duration of 14 years between the first and second investigation (18). In agreement with the results of a review of more than 28 studies, encompassing more than 1000 adults with schizophrenia (9), the mean levels of general intelligence in the patient group in the present study was declined compared with a normal age and education matched population.…”

“…Interestingly, at the second investigation she showed manifest psychotic symptoms, as her BPRS score indicates. Although only a single occurrence, and therefore interpreted with caution, this suggests that the hypothesis that improvement in general intelligence, between the initial postmorbid testing and retesting at some later date, is related to improvement in psychotic symtomatology (18) is not a general reality. Improvement over time in general intelligence could conceivably be more related to the motivation of the schizophrenic patients at the second investigation.…”

Is there change in intelligence quotient in chronically ill schizophrenia patients? A longitudinal study in twins discordant for schizophrenia

“…However, longitudinal studies are more informative as they provide the opportunity to compare the level of IQ within subjects over time. Unfortunately, many longitudinal studies did not include an unaffected control sample (Haywood & Moelis, 1963; Smith, 1964; Hamlin, 1969; Klonoff et al 1970; Russel et al 1997; Bedwell et al 1999; Gold et al 1999; Sheitman et al 2000; Stirling et al 2003; Gochman et al 2005; van Winkel et al 2006; Cervellione et al 2007; Zipparo et al 2008; Carter et al 2010). In fact, some studies that have used healthy controls show that patients do not benefit from practice effects as much as controls do (Hoff et al 2005; Jepsen et al 2010; but see Hoff et al 1999; Heaton et al 2001).…”

Schizophrenia and the myth of intellectual decline

“…The assumption of intellectual deterioration is pervasive in historical views of schizophrenia. Later authors were not able to replicate the findings (13), and some studies reported an increase in IQs over time (14,15). Similarly, Crow (6) highlighted patients with schizophrenia who "progress to a defect state of intellectual impairment with the hallmarks of a dementing illness."…”