Reduced cerebellar cortical volume occurs only in patients with schizophrenia, rather than all those with psychosis, say researchers.
Josselin Houenou (INSERM, Créteil, France) and co-workers found that cerebellar cortical volume on magnetic resonance imaging (MRI) was significantly reduced in 32 patients with schizophrenia, relative to 52 mentally healthy controls, at 47,616 versus 50,678 mm3 in the left hemisphere and 49,518 versus 52,471 mm3 in the right.
By contrast, volumes among 115 patients with bipolar disorder were similar to those in the controls, at 51,614 and 53,136 mm3 for the left and right hemispheres, respectively. And volumes did not differ according to whether or not bipolar disorder patients had psychotic features (53 and 62 patients, respectively).
Cortical volumes were significantly different between schizophrenia and bipolar disorder patients, however.
“This suggests that cerebellar cortex volume reductions may be specific to schizophrenia rather than an overlapping feature between the two disorders”, write the researchers in Acta Psychiatrica Scandinavica. “Furthermore, this suggests a different role for the cerebellum between bipolar disorder and schizophrenia.”
The volume differences remained after accounting for variables including age, gender, history of alcohol or drug abuse and use of lithium and antipsychotics. The team found no differences in cerebellar white matter volumes between the three groups.
Houenou et al suggest that, rather than bipolar disorder patients having no changes in cerebellar morphology, they may instead have “more subtle changes”, that could be picked up by different imaging techniques.
“Moreover, a growing body of evidence, mostly using diffusion weighted imaging, suggests that bipolar disorder is associated with white matter abnormalities”, they say. “Thus, future microstructural assessment of the cerebellar white matter using diffusion MRI rather than assessment of the cerebellar white matter volume may be helpful to understand the involvement of a cerebellar dysfunction in bipolar disorder.”