Visuospatial memory deficits in adolescent onset schizophrenia

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Abstract

Visuospatial memory encoding deficits have been reported in adults with schizophrenia, while adolescents with schizophrenia have not been specifically investigated with visuospatial memory encoding and retrieval paradigms. A cross sectional study of delayed matching-to-sample performance in 19 right handed, male, anti-psychotic medication naïve adolescents with undifferentiated schizophrenia and 28 age, gender, IQ and handedness matched healthy participants was completed. The adolescent-onset schizophrenia group demonstrated significant impairment in visuospatial memory, independent of the degree of delay, consistent with an encoding impairment. The impaired encoding phase of visuospatial memory in the adolescent-onset schizophrenia group is consistent with findings in adult onset schizophrenia samples, suggesting a developmental stage-independent deficit.

Introduction

Visuospatial memory deficits are replicated findings in adults (Bilder et al., 2000) and adolescents (Kravariti et al., 2003a, Kravariti et al., 2003b, Rhinewine et al., 2005) with schizophrenia and those at risk for developing schizophrenia (Brewer et al., 2005, Smith et al., 2006). The magnitude of these deficits ranges between 1 and 2 standard deviations (Rhinewine et al., 2005) and they are qualitatively similar (Kravariti et al., 2003a, Kravariti et al., 2003b, Rund et al., 2004). To date, in adults and adolescents with schizophrenia, the encoding aspect of visuospatial memory, within a broader visuospatial working memory construct, has been specifically implicated (Fleming et al., 1997, Hartman et al., 2002, Leiderman and Strejilevich, 2004). However, adolescents with schizophrenia have not been specifically investigated with visuospatial memory encoding and retrieval paradigms.

The delayed matching-to-sample (DMTS) task from the Cambridge Neuropsychological Test Automated Battery (CANTAB) (Owen et al., 1996) is able to readily parse out encoding from retrieval aspects of visuospatial memory (see Barnett et al., 2005 for detailed reasons). However, to date, investigation of DMTS performance in adults with early phase and chronic adult-onset schizophrenia has revealed encoding deficits (Mathes et al., 2005), while encoding and retrieval deficits have been suggested in first episode adult-onset schizophrenia and those at risk for adult-onset schizophrenia (Wood et al., 2003). Given that the patients with schizophrenia in the latter study were younger and Luciana et al. (2005) have reported that healthy adolescents aged 16 years and over have significantly better DMTS performance than 13–15 year old healthy adolescents, the encoding and retrieval deficits in the younger patients with schizophrenia may be developmental stage dependent: specifically, the encoding deficits may be contributing to the retrieval deficits in the younger patients rather than there being independent retrieval deficits. This study investigates whether the encoding and/or retrieval phases of visuospatial memory are impaired in carefully defined adolescents with schizophrenia. We hypothesize that that there will be encoding deficits alone, consistent with findings in adults with schizophrenia.

Section snippets

Method

Nineteen right-handed male adolescents aged 12–17 years [14.64 (1.85) years] were identified with medication naïve, undifferentiated schizophrenia (DSM-IV, American Psychiatric Association, 1994) during their initial clinical evaluation before active treatment (Vance et al., 2006). This was defined through a semi-structured clinical interview (Schedule for Affective Disorders and Schizophrenia — childhood version (K-SADS), Kaufman et al., 1997) with their parent(s) and with each adolescent (κ > 

Results

Fig. 1 shows the group mean percentage correct accuracy of performance and Table 1 the comparison of accuracy rates between the two groups on all conditions of the DMTS test. MANCOVA indicated a significant effect of group [F(1, 43) = 18.92, p < 0.0005] after controlling for age and full-scale IQ, only the former having a significant independent association with the DMTS accuracy variables [F(1, 43) = 28.33, p < 0.0005]. When averaged across all four conditions, the control group [88.40 (2.93)] made

Discussion

Anti-psychotic medication naïve adolescents with undifferentiated schizophrenia demonstrated subtle yet significant impairment in performance on a visuospatial memory test. Although performance on the memory test was generally worse in the undifferentiated schizophrenia group than the healthy control participants, the pattern of decrease in overall accuracy from the MTS to the 12 second DMTS condition was qualitatively similar in both groups (Fig. 1). Further, although accuracy decreased

Acknowledgements

This work was supported by the Australian Rotary Health Research Fund, The Alfred and the Royal Children's Hospital staff and patients. Dr Bellgrove is supported by the Howard Florey Centenary fellowship from the NH&MRC (Australia).

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