Abstract
Background and Aim: Approximately half of patients with schizophrenia experience a deterioration in IQ before or around illness onset and recent studies have found apositive association between IQ and brain volume in first episode schizophrenia. The aim of this study was to examine the combined impact of estimated IQ trajectory and IQ level at illness onset on psychopathology, neurocognitive profiles and brain volume.
Materials and methods: The design is a cross-sectional, case-control study of 60 first-episode antipsychotic-naïve schizophrenia patients and 60 matched healthy controls. Promorbid IQ was estimated using the Danish Adult Reading Test and current IQ using 4 subtests from Wechsler's Adult Intelligence Scale III. Patients were divided into 4 subgroups based on a combination of both IQ trajectory from premorbid levels (stable vs. deteriorating) and IQ at illness onset (high vs. low) using the healthy controls as reference. The IQ subgroups were compared using psychopathology ratings (Positive and Negative Symptoms Scale), neuropsychological assessments (Brief Assessment of Cognition in schizophrenia and Cambridge Neuropsychological Test Automated Battery) and a combined 3T MRI generated measure of grey and white matter volume corrected for skull size.
Results: Eleven patients (21.5%) were defined as deteriorated low, 10 patients (20%) as deteriorated high, 11 patients (21.5%) as stable low and 19 patients (37%) as stable high. There was a fairly consistent incremental deficit pattern on most of the neurocognitive measures with the subgroups displaying subtle (stable high), circumscribed (deteriorated high), pronounced (stable low) and severe deficits (deteriorated low). There was a signitficant age-related brain volume reduction specifically in the stable low (8.4 ml/year) and the deteriorated low patients (9.0 ml/year), while the stable high (1.1 ml/year) and deteriorated high (1.9 ml/year) were similar to the controls (0.8 ml/year).
Conclusions: Patients with deteriorated low IQ have the most severe and pervasive cognitive deficits and more pronounced age-related volume reductions. Patients with stable low IQ differ from the patients with IQ in the normal range, but to a lesser extent. These findings offer new perspectives in describing the pathophysiological heterogeneity of schizophrenia, supporting the presence of differential neurodevelopmental and neurodegenerative processes.
Materials and methods: The design is a cross-sectional, case-control study of 60 first-episode antipsychotic-naïve schizophrenia patients and 60 matched healthy controls. Promorbid IQ was estimated using the Danish Adult Reading Test and current IQ using 4 subtests from Wechsler's Adult Intelligence Scale III. Patients were divided into 4 subgroups based on a combination of both IQ trajectory from premorbid levels (stable vs. deteriorating) and IQ at illness onset (high vs. low) using the healthy controls as reference. The IQ subgroups were compared using psychopathology ratings (Positive and Negative Symptoms Scale), neuropsychological assessments (Brief Assessment of Cognition in schizophrenia and Cambridge Neuropsychological Test Automated Battery) and a combined 3T MRI generated measure of grey and white matter volume corrected for skull size.
Results: Eleven patients (21.5%) were defined as deteriorated low, 10 patients (20%) as deteriorated high, 11 patients (21.5%) as stable low and 19 patients (37%) as stable high. There was a fairly consistent incremental deficit pattern on most of the neurocognitive measures with the subgroups displaying subtle (stable high), circumscribed (deteriorated high), pronounced (stable low) and severe deficits (deteriorated low). There was a signitficant age-related brain volume reduction specifically in the stable low (8.4 ml/year) and the deteriorated low patients (9.0 ml/year), while the stable high (1.1 ml/year) and deteriorated high (1.9 ml/year) were similar to the controls (0.8 ml/year).
Conclusions: Patients with deteriorated low IQ have the most severe and pervasive cognitive deficits and more pronounced age-related volume reductions. Patients with stable low IQ differ from the patients with IQ in the normal range, but to a lesser extent. These findings offer new perspectives in describing the pathophysiological heterogeneity of schizophrenia, supporting the presence of differential neurodevelopmental and neurodegenerative processes.
| Original language | English |
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| Publication date | 8 Oct 2014 |
| Number of pages | 1 |
| Publication status | Published - 8 Oct 2014 |
| Event | Forskningsdag 2014, Glostrup Hospital - Glostrup, Denmark Duration: 8 Oct 2014 → 8 Oct 2014 |
Conference
| Conference | Forskningsdag 2014, Glostrup Hospital |
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| Country/Territory | Denmark |
| City | Glostrup |
| Period | 08/10/2014 → 08/10/2014 |