Brain metabolism and cognitive impairment in HIV infection: a 3-T magnetic resonance spectroscopy study

Mohamed, Mona A.; Barker, Peter B.; Skolasky, Richard L.; Selnes, Ola A.; Moxley, Richard T.; Pomper, Martin G.; Sacktor, Ned C.

doi:10.1016/j.mri.2010.06.007

« Previous Next »Magnetic Resonance Imaging
Volume 28, Issue 9 , Pages 1251-1257, November 2010

Brain metabolism and cognitive impairment in HIV infection: a 3-T magnetic resonance spectroscopy study☆

Mona A. Mohamed
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD 21287, USA
- F.M. Kirby Center for Functional Brain Imaging, the Kennedy Krieger Institute, Baltimore, MD 21287, USA
Peter B. Barker
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD 21287, USA
- F.M. Kirby Center for Functional Brain Imaging, the Kennedy Krieger Institute, Baltimore, MD 21287, USA
Richard L. Skolasky
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
- Affiliated with the Orthopedic Surgery Department of the Johns Hopkins University School of Medicine and conducted the statistical analysis.
Ola A. Selnes
- Department of Neurology, Johns Hopkins University School of Medicine Baltimore, MD 21287, USA
Richard T. Moxley
- Department of Neurology, Johns Hopkins University School of Medicine Baltimore, MD 21287, USA
Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD 21287, USA
Ned C. Sacktor
- Department of Neurology, Johns Hopkins University School of Medicine Baltimore, MD 21287, USA
- Corresponding author. Tel.: +1 410 550 0978; fax: +1 410 550 0539.

Received 22 January 2010; accepted 11 June 2010. published online 05 August 2010.

Abstract

Background and Purpose

Human immunodeficiency virus (HIV)-associated dementia (HAD) has been extensively studied using magnetic resonance spectroscopy (MRS) at field strengths of 1.5 T. Higher magnetic field strengths (such as 3 T) allow for more reliable determination of certain compounds, such as glutamate (Glu) and glutamine (Gln). The current study was undertaken to investigate the utility of 3-T MRS for evaluating HIV+ patients with different levels of cognitive impairment with emphasis on the measurement of Glu and Glx (the sum of Glu and Gln).

Methods

Eighty-six HIV+ subjects were evaluated at 3 T using quantitative short echo time single-voxel MRS of frontal white matter (FWM) and basal ganglia (BG). Subjects were divided into three groups according to the Memorial Sloan Kettering (MSK) HIV dementia stage: 21 had normal cognition (NC) (MSK 0), 31 had mild cognitive impairment (MCI) without dementia (clinical MSK stage=0.5), and 34 had dementia (HAD) (MSK≥1). HIV+ subjects had also undergone standardized cognitive testing covering the domains of executive function, verbal memory, attention, information processing speed and motor and psychomotor speed. Between-group differences in metabolite levels in FWM and BG were evaluated using ANOVA. Pearson correlation coefficients were used to explore the associations between the Glu and Glx metabolites and neurocognitive results.

Results

FWM Glx was lower in HAD (8.1±2.1 mM) compared to both the MCI (9.17±2.1 mM) and NC groups (10.0±1.6 mM) (P=.006). FWM myo-inositol (mI) was higher in HAD (4.15±0.75 mM) compared to both MCI (3.86±0.85 mM) and NC status (3.4±0.67 mM) (P=.006). FWM Glx/creatine (Cr) was lower and FWM mI/Cr was significantly higher in the HAD compared to the MCI and NC groups (P=.01 and P=.004, respectively). BG N-acetyl aspartate (NAA) was lower in the HAD group (6.79±1.53 mM), compared to the MCI (7.5±1.06 mM) and NC (7.6±1.01 mM) groups (P=.036). Significant negative correlations were observed between Glu, Glx and NAA concentrations with Trail-Making Test B (P=.006, P=.0001 and P=.007, respectively), and significant positive correlation was found with the Digit symbol test (P=.02, P=.002 and P=.008, respectively). FWM Glx and NAA concentrations showed negative correlation with Grooved Pegboard nondominant hand (P=.02 and P=.04, respectively).

Conclusion

Patients with HAD have lower levels of Glx concentrations and Glx/Cr ratio in FWM, which was associated with impaired performance in specific cognitive domains, including executive functioning, fine motor, attention and working memory performance. Three-Tesla MRS measurements of Glx may be a useful indicator of neuronal loss/dysfunction in patients with HIV infection.

Keywords: HIV dementia, MR spectroscopy, Glutamate, Glx