Morphological Changes of Frontal Areas in Male Individuals With HIV: A Deformation-Based Morphometry Analysis

Characteristics of cortical thickness in treated HIV-infected individuals with and without cognitive impairment

BACKGROUND

HIV can alter the brain structure and function in the early stage of infection. This study investigated the differences in cortical thickness patterns between healthy controls (HCs) and people living with HIV (PLWH) with asymptomatic neurocognitive impairment (ANI) or cognitive integrity (CI).

METHODS

Twenty-one ANI, 25 CI, and 24 HCs were recruited and underwent high-resolution T1-weighted magnetic resonance images. Cortical thickness was analyzed using the Computational Anatomy Toolbox, and the correlation analysis was conducted between cortical thickness and clinical and neuropsychological variables.

RESULTS

Both CI and ANI exhibited decreased cortical thickness, primarily in the left frontal cortices and bilateral limbic system. ANI demonstrated a more pronounced and widespread pattern of cortical thinning. Lower CD4+ counts and higher peak plasma viral load were associated with decreased cortical thickness of the right pericallosal sulcus and middle-posterior part of cingulate gyrus and sulcus in ANI. Conversely, compared to HCs, both ANI and CI showed cortical thickening in the left insula cortex, and ANI tended to have a thicker cortex. Moreover, the increased thickness of left insula cortex in both CI and ANI were positively correlated with attention and working memory.

CONCLUSIONS

The cortical thickness thinning was observed in the frontal and limbic systems in both ANI and CI. Meanwhile, the thickening of the insular cortex may represent mild neuroinflammation or a transient compensatory mechanism. This study provides new insights into the neural mechanisms underlying HIV-related cognitive impairment and highlights the importance of cortical thickness alteration patterns when assessing cognitive function of PLWH.

Altered angular gyrus activation during the digit symbol substitution test in people living with HIV: beyond information processing speed deficits

Speed-of-information processing (SIP) is often impaired in people living with HIV (PLWH), typically assessed through tests such as the digit symbol (DS) and symbol search, which also rely on motor and executive functions. This study aims to disentangle SIP deficits from other cognitive impairments in PLWH using an MRI-adapted digit symbol substitution test (mDSST). Fifty-seven PLWH (34.7 ± 11.2 years) and 50 age-matched people living without HIV (PLWoH, 31.8 ± 9.9 years) completed standardized neuropsychological tests and the mDSST. Behavioral performances and brain activations were compared, with correlations drawn between group-differentiating brain activations and clinical ratings of cognitive domains. Results showed that PLWH performed worse in DS and symbol search, made fewer responses, and was slower in mDSST, with performances correlating to SIP and motor ratings. Notably, PLWH showed greater deficits in attention compared to PLWoH, rather than in SIP or motor. PLWH also exhibited greater primary motor cortex activation and reduced right angular gyrus activation. These findings suggest that slower performances on SIP-related tests in PLWH may be partially linked to abnormal visuospatial attention, as reflected by reduced angular gyrus activation, with higher motor cortex activation potentially serving as a compensatory mechanism. Future studies should explore whether prefrontal regions implicated in SIP are impaired in more severely affected PLWH.

Neuroimaging advances in neurocognitive disorders among HIV-infected individuals

Although combination antiretroviral therapy (cART) has been widely applied and effectively extends the lifespan of patients infected with human immunodeficiency virus (HIV), these patients remain at a substantially increased risk of developing neurocognitive impairment, commonly referred to as HIV-associated neurocognitive disorders (HAND). Magnetic resonance imaging (MRI) has emerged as an indispensable tool for characterizing the brain function and structure. In this review, we focus on the applications of various MRI-based neuroimaging techniques in individuals infected with HIV. Functional MRI, structural MRI, diffusion MRI, and quantitative MRI have all contributed to advancing our comprehension of the neurological alterations caused by HIV. It is hoped that more reliable evidence can be achieved to fully determine the driving factors of cognitive impairment in HIV through the combination of multi-modal MRI and the utilization of more advanced neuroimaging analysis methods.

Altered metabolism in right basal ganglia associated with asymptomatic neurocognitive impairment in HIV-infected individuals

Background

Only few studies have focused on the metabolite differences between asymptomatic neurocognitive impairment (ANI) and cognitively normal people living with HIV (PLWH). The current study aims to examine whether brain metabolisms in basal ganglia (BG) by magnetic resonance spectroscopy (MRS) were potential to discriminate ANI from cognitively normal PLWH.

Methods

According to neuropsychological (NP) test, 80 PLWH (37.4 ± 10.2 years) were divided into ANI group (HIV-ANI, n = 31) and NP normal group (HIV-normal, n = 49). Brain metabolisms by MRS from right BG were compared between groups, including N-acetylaspartate and N-acetyl aspartylglutamate (tNAA), creatine and phosphocreatine (tCr), and choline-containing compounds (tCho). A total value of three metabolites were introduced. All brain metabolisms were evaluated as its percentage of total. Furthermore, correlations between MRS and NP and clinical measures were evaluated. A logistic regression model was applied, and the AUC values for the model and the continuous factors were compared using receiver operating curve (ROC) analysis.

Results

Compared to HIV-normal group, tNAA/total was lower and tCr/total was higher in the HIV-ANI group (P < 0.05). Both tNAA/total and tCr/total values were correlated with NP score (P < 0.05), especially in verbal fluency, speed of information processing, learning, and recall (P < 0.05). The logistic model included BG-tCr/total, current CD4 and infection years of PLWH. The AUC value for the BG-tCr/total was 0.696 and was not significantly lower than that for logistic model (P < 0.01).

Conclusion

The altered brain metabolites in the right BG were found in the ANI group compared to PLWH with normal cognition, and further associated with NP deficits. The current findings indicated that brain metabolites assessed by MRS has the potential to discriminate ANI from cognitively normal PLWH.