Academic journal article Hong Kong Journal of Psychiatry

Prediction of Rehabilitative Success after 1 Year with Early Visual Processing Measures

Academic journal article Hong Kong Journal of Psychiatry

Prediction of Rehabilitative Success after 1 Year with Early Visual Processing Measures

Article excerpt

Abstract

Objective: There is a paucity of literature exploring the relationship between early visual processing measures (span of apprehension test and degraded-continuous performance test) and community functioning. The existing literature draws mixed and conflicting conclusions about the significance of early visual processing measures on community functioning.

Patients and Methods: In a group of 66 patients with chronic schizophrenia recruited from a rehabilitation unit in a psychiatric hospital in Hong Kong, baseline measures of positive symptoms, negative symptoms, and early visual processing measures were collected within 2 weeks of recruitment into the study. Day care and night care service data were collected from the hospital database and verified with outpatient case records and information collected from care staff.

Results: Principal component analyses of the baseline measures yielded 4 factors corresponding to early visual processing factor, positive symptoms, negative symptoms, and degraded-continuous performance test measures. Early visual processing measures made up of degraded-continuous performance test overall sensitivity and correct rates of span of apprehension test matrix 3, span of apprehension test matrix 12, and span of apprehension test overall correct rate correctly classified 40% of day care services and 62% of hospitalisation status.

Conclusion: The possible mechanism of early visual processing measures in mediating care service requirements is discussed.

Key words: Care services, Schizophrenia

Introduction

There is an increasing surge of interest in the functional consequences of neurocognitive deficits in schizophrenia. There is emerging evidence that neurocognitive measures that are most significantly related to functional outcomes are secondary verbal memory, working memory, executive function, and vigilance. (1) Functional outcomes are defined as success in psychosocial skill acquisition, laboratory assessment of instrumental skills and social problem solving ability, and community outcome/daily activities. In a review of 37 studies, (1) the meta-analysis concluded that weighted effect sizes of the 4 neurocognitive domains are not negligible (pooled estimate ranged from 0.29 to 0.40).

Among the 4 neurocognitive variables, vigilance has the smallest effect size (0.20), due to the limited number of available studies (n = 17). Of these 17 studies, 9 supported a positive relationship between vigilance and community outcome, while 8 found no relationship. Vigilance refers to the ability to maintain a response to a signal and not respond to noise. Vigilance is typically measured by the continuous performance test (CPT). (2) Early visual processing is another neurocognitive domain that has been mentioned in the review to have some positive relationship with social problem solving, but due to the limited number of studies (n = 4), this variable is not powerful enough for subsequent meta-analysis. It is interesting to note that in 3 of the 4 studies included in Green's meta-analysis, there is a strong positive correlation between early visual processing and social problem solving skills. (1) Visual processing deficit in schizophrenia is measured by the span of apprehension test (SPAN), a test of ability to visually scan a display of competing stimuli and identify the visual target stimulus (a 'T' or an 'F'). (3) In Bowen et al's study of chronic stable inpatients with schizophrenia, there was a strong correlation between degraded-CPT and interpersonal performance scales (r = 0.49-0.58, p < 0.01), and strong correlation between degraded-CPT and elemental skills training measures (r = 0.50-0.66, p < 0.01), as well as between SPAN and some elemental skills training measures (listening skills and SPAN, r = 0.67; total elemental skills score and SPAN, r = 0.55). (4) In fact, as mentioned in Green's (1) review, Bowen et al's (4) study is the study with the largest reported correlation between cognitive deficits and community outcome, suggesting that these 2 neurocognitive deficits tapping early visual processing deficits might be of value in predicting success in community adjustment. …

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