Very few similarities between the brains of schizophrenia patients Research at group level says little about the individual patient

16 October 2018

Patients with a diagnosis of schizophrenia are a heterogenous group with large differences between individuals. Researchers at the Radboudumc, together with colleagues from England and Norway, showed that only a negligible number of identical features in the brain occur in more than two percent of patients. Therefore, they state that insights based on research at group level say very little about individual patients. The results of this study are published in JAMA Psychiatry.

Patients with a diagnosis of schizophrenia have an extremely variable representation of their psychiatric disorder. The diagnosis is made on the basis of the presence of psychoses and specific behavioural symptoms.
Thomas Wolfers and André Marquand of Radboudumc investigated how much the brains of individual patients differ from the average patient with the diagnosis of schizophrenia. To do this, they first compared brain scans of 250 healthy subjects with those of 218 patients with schizophrenia. Schizophrenic patients were found to differ significantly from healthy subjects in the frontal brain region, the cerebellum and the temporal cortex.

Individual differences

However, when studying individual patients, the differences were so great that there was no average schizophrenic patient. Only a few identical abnormalities in the brain occurred in more than two percent of patients.The largest number of deviations manifested itself on an individual level, says Marquand: "The brains of individual patients with schizophrenia deviate so much from an average that there are very few similarities in the brains of patients with the same diagnosis. Average abnormalities are only a small part of the biological background of patients diagnosed with schizophrenia. The largest variabilities are those found between individual patients."

Personalized diagnosis

The research shows that almost every patient with schizophrenia has its own biological profile. The current method of making a diagnosis of psychiatric disorders based on symptoms has no demonstrable biological basis, says Marquand: "Variation between patients is reflected in the brain, but despite this enormous variation all these people get the same diagnosis. Thus, we cannot achieve a better understanding of the biology behind schizophrenia by studying the average patient. We need to understand for each patient individual what the causes of a disorder may be. Insights based on research at group level say little about the individual patient."

Fingerprint

The researchers want to make a fingerprint of individual brains on the basis of differences in relation to a group average. This should lead to a better understanding of the specific diagnosis of each individual patient. Wolfers: "Psychiatrists and psychologists know very well that each individual patient is an individual with its own tale, history and biology. Nevertheless, we use diagnostic models that largely ignore these differences. Together with our colleagues in Europe we raise this issue by developing methods that make it possible to view the individual as a whole. We look at both the symptoms and the biology of the brain. It is certainly a long way before this research will find its translation into clinical practice, but in the long term we hope to be able to develop better diagnoses and individualized therapies for patients."

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