Biomedical subjects

Hugo G Schnack

Publications and source records attributed to Hugo G Schnack.

3 recordsLinked to original sources

PubMed2002

Brain volume changes in first-episode schizophrenia: a 1-year follow-up study.

BACKGROUND: Imaging studies of patients with schizophrenia have demonstrated that brain abnormalities are largely confined to decreases in gray matter volume and enlargement of the lateral and third ventricles. Global gray matter volume has been reported to progressively decrease in childhood-onset and chronic schizophrenia. Global gray matter volumes have not been examined longitudinally in patients with first-episode schizophrenia. One would expect global gray matter to decrease progressively, particularly in first-episode patients, because clinical deterioration is greatest in the early stages of the disease. METHODS: Patients with first-episode schizophrenia who had taken antipsychotic medication for 0 to 16 weeks (n = 34) and matched healthy comparison subjects (n = 36) were included in the study. For all subjects, magnetic resonance imaging scans of the whole brain were obtained at inclusion and after 1 year (mean [SD], 12.7 [1.1] months). Outcome was measured 2 years after inclusion. To compare morphological changes over time between patients and healthy comparison subjects, multiple repeated-measures analyses of variance were conducted with intracranial volume as a covariate. Outcome and cumulative antipsychotic medication were related to changes in patients' brain volumes. RESULTS: Total brain volume (-1.2%) and gray matter volume of the cerebrum (-2.9%) significantly decreased and lateral ventricle volume significantly increased (7.7%) in patients. The decrease in global gray matter volume significantly correlated with outcome and, independently of that, with higher cumulative dosage of antipsychotic medication. CONCLUSIONS: The loss of global gray matter in schizophrenia is progressive, occurs at an early stage of the illness, and is related to the disease process and antipsychotic medication.

Adolescent↗

PubMed2002

Twin-singleton differences in brain structure using structural equation modelling.

Twin studies are important to investigate genetic influences on variation in human brain morphology in health and disease. However, the twin method has been criticized for its alleged non-generalizability due to differences in the intrauterine and family environment of twins, compared with singletons. To test whether twin-singleton differences complicate interpretation of genetic contributions on variation in brain volume, brains from 112 pairs of twins and 34 of their siblings with a mean (standard deviation) age of 30.7 (9.6) years were scanned using MRI. The influence of birth order, zygosity and twin-sibling differences on brain volume measures was analysed using maximum-likelihood model fitting. Variances were homogeneous across birth order, zygosity and twin-singleton status. Irrespective of zygosity, intracranial volume was smaller in second-born twins compared with first-born twins and compared with siblings. Grey matter volume was smaller in second-born twins compared with first-born twins. White matter was smaller in twins compared with siblings. Differences in grey and white matter between these groups were no longer significant after correction for intracranial volume. Total brain, and lateral and third ventricle volumes were comparable in twins and singletons. In conclusion, second-born twins have a smaller intracranial volume than their first-born co-twins and siblings. This suggests aberrant early brain development in second-born twins, which is consistent with the suboptimal pre- and perinatal environment related to birth order in twins. Since other brain volume measures were comparable between the groups, twin studies can provide reliable estimates of heritabilities in brain volume measures and these can be generalized to the singleton population.

Adult↗

PubMed2002

Volume changes in gray matter in patients with schizophrenia.

OBJECTIVE: Schizophrenia is generally characterized by a progressive decline in functioning. Although structural brain abnormalities, particularly decrements in gray matter volume, are considered important to the pathology of schizophrenia, it is not resolved whether the brain abnormalities become more prominent over time. METHOD: Magnetic resonance brain images from 159 patients with schizophrenia and 158 healthy comparison subjects between 16 and 70 years of age were compared. Using linear regression analysis, the authors analyzed the relationship between the volumes of the total brain, gray and white matter, cerebellum, and lateral and third ventricles with patient age. RESULTS: Total brain (-2.2%), cerebral gray matter (-3.3%), prefrontal gray matter (-4.4%), and prefrontal white matter (-3.5%) volumes were smaller, and lateral (27%) and third (30%) ventricle and peripheral CSF (11%) volumes were larger in schizophrenia patients. A significant group-by-age interaction for gray matter volume was found, as shown by a steeper regression slope between age and gray matter volume in patients (-3.43 ml/year) than in healthy comparison subjects (-2.74 ml/year). CONCLUSIONS: The smaller brains of the patients with schizophrenia can be explained by decreases in gray matter volume. Moreover, the finding that the smaller gray matter volume was more pronounced in older patients with schizophrenia may suggest progressive loss of cerebral gray matter in schizophrenia patients.

Adolescent↗