Fig. 3

Group differences in DTI diffusivities. A Regions of interest automatically segmented for DTI measures that showed most of the significant HIV or MJ main effects. B Regardless of MJ use status, HIV+ group showed higher axial diffusivity (AD) in the right body of the corpus callosum (BCC), left splenium of the corpus callosum (SCC), left superior longitudinal fasciculus (SLF), left superior corona radiata (SCR), and right superior fronto-occipital fasciculus (SFO), than SN participants. However, regardless of HIV serostatus, MJ users had lower AD in the right uncinate fasciculus (UNC, p = 0.024) than nonusers. C Compared to SN controls and regardless of MJ use status, HIV+ had higher radial diffusivity (RD) than SN participants in the bilateral anterior limb of the internal capsule (ALIC), bilateral posterior corona radiata (PCR), left SCR, and left SLF, as well as 6 other brain regions (see Table 3). D Regardless of MJ use status, HIV+ group had higher mean diffusivity (MD) in the right caudate, left and right globus pallidus (GP), and left thalamus than SN groups. In additional, HIV-by-marijuana use showed an interaction effect in the right GP (p = 0.029); while HIV + MJ users had higher MD than HIV nonusers, SN-MJ users had lower MD than SN nonusers. SN, HIV-seronegative nonuser group; SN + MJ, HIV-seronegative marijuana user group; HIV, HIV-seropositive nonuser group; HIV + MJ, HIV-seropositive marijuana user group. Red star: p value remained significant after Holm-Bonferroni correction for multiple comparisons