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| Publication Abstract Display | | Type: Published Abstract | | Title: HIV and methamphetamine related diffusion effects. | | Authors: Archibald SL, Jacobson MW, Theilmann R, Ogasawara M, Woods SP, Grant I, Jernigan TL | | Year: 2009 | | Publication: Society for Neuroscience, Chicago, Illinois | | Volume: Issue: Pages: | | Abstract:Introduction: HIV disease is characterized by neurodegenerative changes in white matter, basal ganglia and cortical structures. In contrast, methamphetamine dependence (METH) has been associated with a pattern of volume increases in basal ganglia and parietal lobe regions. Some morphometry studies of HIV and METH, which have a high comorbidity, suggest that opposing effects of atrophy and hypertrophy are superimposed in dually affected individuals, especially in the caudate nucleus. A recent functional MRI study in our laboratory demonstrated interaction effects of dual HIV and METH exposure beyond the single factor effects. Studies using diffusion imaging have shown changes in white matter integrity in both HIV and METH but little is known about their combined effects. This study examined white matter microstructure using diffusion in groups exposed to HIV and METH, alone and in combination.
Subjects: Thirty-seven participants were recruited from the UCSD HIV Neurobehavioral Research Center from 4 groups: community controls with neither of the risk factors, a group with HIV only, a group with METH only, and a group who had both HIV and METH. METH subjects met DSM-IV criteria for dependence in the past 18 months but were abstinent at assessment. Groups were well matched on age, gender and years of education. Singly and dually affected groups did not differ significantly on HIV disease parameters or METH use histories. The 3 patient groups showed significant cognitive impairment relative to controls.
Methods: Imaging was performed on a 3T GE Excite system. The diffusion weighted sequence had 15 directions, b=1250, and 32 4mm slices and field maps were collected for unwarping. Diffusion images were analyzed using Tract Based Spatial Statistics (TBSS). Whole brain measures of mean diffusivity (MD) and fractional anisotropy (FA) from the skeleton produced by TBSS were compared across groups using analysis of variance.
Results: There were no group differences in FA in this small sample. The ANOVA for the MD values however was significant (p<.05). Although not significant, the HIV and METH groups tended to be higher than controls as expected. However, an unanticipated finding was that the main effect was due to significantly lower MD in the HIV/METH group relative to the single risk groups.
Conclusions: While increased MD is usually associated with myelin or axon loss, decreased diffusivity may indicate an inflammatory response or swelling of the white matter spaces. This result adds to evidence that the combined effects of HIV and METH on brain structure is complex and not simply additive. |
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