Intellectual Deficits in First-Episode Schizophrenia: Evidence for Progressive Deterioration

Abstract

The developmental processes leading to neuropsychological deficits in schizophrenia are poorly understood. Both early developmental defects and subsequent deterioration may occur. Intelligence test profiles are often used to estimate premorbid ability and deterioration from prior levels of functioning. These characteristics were assessed in samples of first-episode (n = 51) and chronic (n = 50) schizophrenic patients. Although the groups showed few differences on tests to estimate premorbid intellectual ability, the chronic group performed worse on measures considered sensitive to deterioration. Dextral (right-handed) patients tended to have better performance; this effect was marked in the first-episode sample, especially on verbal tests. Male patients showed more evidence of deterioration than female patients. Subgroups differing in the time course of premorbid social dysfunction also differed in intelligence test profiles, suggesting that estimates of social and cognitive deterioration may have concurrent validity. The results support the hypothesis that patients differ in the course of cognitive decline and suggest that deterioration of function may follow the onset of overt psychosis in some patients. Prospective longitudinal studies of first-episode schizophrenic patients could directly test this hypothesis.

Computerized Neurocognitive Scanning: II. The Profile of Schizophrenia

“…The lack of difference in over-all severity and pattern of neurocognitive profile between neuroleptic naive and previously treated patients confirms earlier reports (Bilder et al 1992;Gur et al 1998Gur et al , 1999bHoff et al 1991;Saykin et al 1994). This indicates that diffuse and significant cognitive deficits are evident at first clinical presentation before initiation of treatment.…”

“…Are they affected by treatment and relate to outcome? Studies addressing these questions have indicated that: neurocognitive deficits are apparent at first clinical presentation in neuroleptic-naive patients (Bilder et al 1992;Hoff et al 1991;Saykin et al 1994); while stable, some show improvement with treatment (Censits et al 1997), especially with atypical neuroleptics (Buchanan et al 1994;Daniel et al 1996;Green et al 1997;Hagger et al 1993); and they show limited relation to clinical symptoms (Censits et al 1997), but do relate to functional outcome (Bellack et al 1999;Green 1996).…”

Neurodevelopmental origin of cognitive impairment in schizophrenia

“…However, one of the challenges of the neurodevelopmental model is that both timing of the emergence and level of severity of functional deficits are variable and these deficits are not always apparent before the illness. Although some patients with schizophrenia have a clear history of pre-morbid intellectual difficulties from childhood and have low functioning throughout their life, many others experience functional decline during prodrome or early years of the illness after seemingly normal early development (Bilder et al 1992;Kelley et al 1992;Doody et al 1998;Addington & Addington, 2005;Morgan et al 2008;Foussias & Remington, 2010;Strauss et al 2012). It is also evident that some chronic and older-age patients with schizophrenia have very significant functional deficits compared to their level of functioning in earlier years of the illness (Davidson et al 1995;Harvey & Davidson, 2002).…”

Neuropsychological evidence supporting a neurodevelopmental model of schizophrenia: a longitudinal study

“…Evidence for impaired learning and memory (e.g., Calev et al, 1983;Saykin et al, 1991;Goldberg et al, 1993), attention (e.g., Nuechterlein and Dawson, 1984;Harvey et al, 1990;Nestor et al, 1992), and executive functions (e.g., Goldberg et al, 1987;Morrison-Stewart et al, 1992) has supported a model of fronto-temporal dysfunction in schizophrenia. The presence of these deficits at first presentation (e.g., Bilder et al, 1992;Saykin et al, 1994), combined with the lack of correlation with measures of chronicity (e.g., Goldberg et al, 1993;Nopoulos et al, 1994) are consistent with the neurodevelopmental hypothesis that stresses the relative stability of cognitive functions after the onset of schizophrenia (e.g., Weinberger, 1987;Wyatt, 1996). The cross-sectional rather than longitudinal design used in the majority of studies, however, precludes a rigorous test of the degenerative hypothesis since crosssectional paradigms do not compare the same individuals at different times within the course of their illness.…”