Neuropsychiatric disorder classification challenges clinicians and researcher alike. Classical approaches have used a distinct non-overlapping categories approach. Increasingly, research suggests that distinct disorders share clinical and neuroanatomical features. This means that it might be possible for specific genes and environmental effects to produce more than one disorder.
Cheung et al from the University of Hong Kong, China explored brain structural commonalities between autism and schizophrenia. Using a novel statistical classification strategy, MRI data were compared in a group of 308 subjects with autism, 352 with first-episode schizophrenia and 801 controls. The strategy group anatomical differences into those found in autism alone, schizophrenia alone and in both autism and schizophrenia (figure).
The authors used a series of imaging data sets to perform their analysis. The autism group included several clinical groups including autism, Asperger’s and high-functioning autism. The schizophrenia group were all first-psychotic episode with some being antipsychotic naïve and some with a history of antipsychotic drug exposure.
The figure from the manuscript shows the grouping for various brain regions grouped by frontal/parietal region/temporal lobe-basal ganglia region and cerebellum. Both diagnostic groups demonstrated gray matter reductions in the right posterior cingulate, the right parahippocampal gyrus, putamen and left thalamus.
Subjects with schizophrenia demonstrated many more local regions of atrophy not found in autism including the right and left superior and medial frontal gyrus, right and left cingulated and left insula, caudate, temporal gyrus and amygdala. The only unique site of gray matter atrophy for the autism group was the left putamen.
The authors note that these two disorders are “indicative of overlapping neuroanatomical phenotype” but do not imply that autism and schizophrenia are a “common entity”. The authors conclude: “Our findings should therefore encourage further exploration of the potential shared etiologies and better understanding of the mechanisms separating the 2 conditions”.
I think you will see increasing research examining commonalities between what have up until now been considered distinct conditions. Look for more evidence that distinct disorders have significant phenotype overlap. Examining these shared features may provide a better understanding of the pathophysiology of a variety of mental disorders.
Figure Provided from PloS One Manuscript
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