Use of inverse probability weighting to adjust for non-participation in estimating brain volumes in schizophrenia patients.
ABSTRACT Low participation is a potential source of bias in population-based studies. This article presents use of inverse probability weighting (IPW) in adjusting for non-participation in estimation of brain volumes among subjects with schizophrenia. Altogether 101 schizophrenia subjects and 187 non-psychotic comparison subjects belonging to the Northern Finland 1966 Birth Cohort were invited to participate in a field study during 1999-2001. Volumes of grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF) were compared between the 54 participating schizophrenia subjects and 100 comparison subjects. IPW by illness-related auxiliary variables did not affect the estimated GM and WM mean volumes, but increased the estimated CSF mean volume in schizophrenia subjects. When adjusted for intracranial volume and family history of psychosis, IPW led to smaller estimated GM and WM mean volumes. Especially IPW by a disability pension and a higher amount of hospitalisation due to psychosis had effect on estimated mean brain volumes. The IPW method can be used to improve estimates affected by non-participation by reflecting the true differences in the target population.
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ABSTRACT: Neurodevelopmental and neurodegenerative theories may be viewed as incompatible accounts that compete to explain the pathogenesis of schizophrenia. However, it is possible that neurodevelopmental and neurodegenerative processes could both reflect common underlying causal mechanisms. We hypothesized that cognitive dysfunction would gradually deteriorate over time in schizophrenia and the degree of this deterioration in adulthood would be predicted by an infant measure of neurodevelopment. We aimed to examine the association between age of learning to stand in infancy and deterioration of cognitive function in adulthood. Participants were nonpsychotic control subjects (n = 76) and participants with schizophrenia (n = 36) drawn from the Northern Finland 1966 Birth Cohort study. The schizophrenia group showed greater deterioration in abstraction with memory than controls, but there were no differences between schizophrenia and controls in rate of change of other cognitive measures. Age of learning to stand in infancy significantly inversely predicted later deterioration of abstraction with memory in adult schizophrenia (later infant development linked to greater subsequent cognitive deterioration during adulthood), possibly suggesting a link between abnormal neurodevelopmental and neurodegenerative processes in schizophrenia.Schizophrenia Bulletin 03/2014; · 8.61 Impact Factor