Altered Cortical Folding May Help Predict Psychosis

Magnetic resonance imaging can be used to detect the development of psychosis in the brains of high-risk patients at an early stage, researchers from the University of Basel and Western University report.

Early detection of psychosis increases the chances of effective treatment. Despite advances in diagnosis, however, it has previously not been possible to examine young people with initial psychotic symptoms and reliably say who will develop acute psychosis and who will not.

It has long been supposed that the condition is caused by disturbed communication between various groups of nerve cells. Modern imaging techniques have made it possible to make these connections between regions of the brain visible.

Researchers from the University of Basel have now examined the question of whether changes in the anatomical structure of brain networks can already be detected in people with an increased risk of psychosis. The study was carried out in collaboration with scientists from the Psychiatric University Clinics Basel, Western University and Lawson Health Research Institute in Ontario, Canada.

Cortical Folding

The researchers, led by Drs André Schmidt and Lena Palaniyappan, focused on cortical folding, known as gyrification: they examined how the folds in various regions of the brain interact with each other, and whether this interaction is impaired in high-risk patients.

They also tested how precisely they could use the cortical connectivity to predict which high-risk patients would suffer from psychosis and which would not.

Gyrification is the process of forming the characteristic folds of the cerebral cortex. The peak of such a fold is called a gyrus (plural: gyri), and its trough is called a sulcus (plural: sulci).

The neurons of the cerebral cortex reside in a thin layer of gray matter, only 2–4 mm thick, at the surface of the brain. Much of the interior volume is occupied by white matter, which consists of long axonal projections to and from the cortical neurons residing near the surface.

Gyrification allows a larger cortical surface area and hence greater cognitive functionality to fit inside a smaller cranium. In most mammals, gyrification begins during fetal development.

Reduced Integration

For their study, the researchers examined 44 healthy control subjects, 38 patients with first-episode psychosis, and 79 people with an increased risk of psychosis, of which 16 later developed fully-formed psychosis.

They reconstructed the brain’s nerve pathways using magnetic resonance imaging and methods from mathematical graph theory, with which they described a network of nodes.

The results show that in comparison to the healthy control group, the folding in individual regions of the brain in patients with an initial psychotic episode and those with a later psychosis transition showed reduced integration and increased segregation.

The analysis also showed that this process enabled predictions to be made with more than 80% accuracy about which patients would later suffer from psychosis and which would not.

Support for the research came from the Universitäre Psychiatrische Kliniken [UPK] Basel, the Bucke Family Fund, Chrysalis Foundation Fund, Opportunities Fund from the Academic Medical Organization of South Western Ontario, and Canadian Institutes of Health Research Foundation.

Das T, Borgwardt S, Hauke DJ, et al.
Disorganized Gyrification Network Properties During the Transition to Psychosis
JAMA Psychiatry. Published online April 25, 2018. doi:10.1001/jamapsychiatry.2018.0391

Image: University Psychiatric Clinics Basel