The Effect of Aripiprazole versus Risperidone on Prefrontal Brain Metabolite Levels and Brain Volume in Psychotic Disorders: An Exploratory StudyAuthor(s): Edith J Liemburg, Anita Sibeijn-Kuiper, Henderikus Knegtering, Andre Aleman
Objective: Given that aripiprazole acts as a partial agonist on the dopamine receptor, it may have unique effects on brain neuro-metabolism, specifically in the prefrontal cortex. In this exploratory study, we investigated the effect of aripiprazole compared to risperidone on prefrontal metabolite levels (Glx, NAA, Creatine, Choline and myo-Inositol) and changes in gray and white matter volume (GMV and WMV) in patients with a psychotic disorder. We hypothesized that patients treated with aripiprazole would show increased levels of Glx and NAA and preserved brain volumes, in contrast to risperidone.
Methods: In this randomized, single blind study, patients (n=24) treated with either risperidone or aripiprazole underwent magnetic resonance spectroscopy (1H-MRS) and high-resolution anatomical scans (3T) at baseline and after 9 weeks. LC Model was used to determine the absolute spectral metabolite levels and SPM12 was to perform voxel based morphometry analyses. Both metabolite levels and brain volumes were compared between treatment groups.
Results: We found a trend for a different effect of both antipsychotics on Glx levels, whereby risperidone reduced Glx levels compared to aripiprazole. Moreover, patients treated with aripiprazole showed a decreased GMV in the precentral gyrus, caudate and lateral frontal regions and increased WMV in the precentral gyrus and a non-significant but consistent pattern of prefrontal WM increases, in contrast to risperidone.
Conclusion: Our results point to possibility of different effects of aripiprazole on brain volume and metabolism compared to risperidone. Studies in larger samples are needed to shed more light on the robustness and nature of such differences.