METAANALYSIS OF BRAIN AND CRANIAL SIZE IN SCHIZOPHRENIA

Several meta-analyses are presented that address the issue of brain an d/or cranial size reductions in schizophrenia. Separate meta-analyses were conducted for brain size (n = 27 studies), intracranial size (n = 18) or extracranial size (n = 8). For each meta-analysis, the weighte d composite effect size (d) was tested for statistical significance (t he direction of the effect size was negative if patients with schizoph renia had smaller structure size than controls). The influence of seve ral potential modifiers of effect size (age, methods, region, gender) was individually evaluated. The composite effect sizes for studies of brain, intracranial and extracranial measures were d = -0.26, (p<0.000 1), d = -0.18, (p = 0.0012), and d = +0.14, (p = 0.16), respectively. Thus, the review found evidence for a small, but statistically signifi cant reduction in brain and intracranial size in schizophrenia, but no evidence for a reduction in extracranial size. Studies based on axial image slices had significantly larger effects (d= -0.60) than the stu dies based on sagittal images (d= -0.09)(chi(2) = 14.0, p = 0.0002). I n summary, the findings clearly support a small yet highly significant reduction of brain and intracranial size in schizophrenia.