Psychiatric and neurophysiological predictors of obesity in HIV/AIDS

Neuroimaging and Cognitive Evidence for Combined HIV-Alcohol Effects on the Central Nervous System: A Review

Alcohol use disorder (AUD) among people living with HIV (PLWH) is a significant public health concern. Despite the advent of effective antiretroviral therapy, up to 50% of PLWH still experience worsened neurocognition, which comorbid AUD exacerbates. We report converging lines of neuroimaging and neuropsychological evidence linking comorbid HIV/AUD to dysfunction in brain regions linked to executive function, learning and memory, processing speed, and motor control, and consequently to impairment in daily life. The brain shrinkage, functional network alterations, and brain metabolite disruption seen in individuals with HIV/AUD have been attributed to several interacting pathways: viral proteins and EtOH are directly neurotoxic and exacerbate each other's neurotoxic effects; EtOH reduces antiretroviral adherence and increases viral replication; AUD and HIV both increase gut microbial translocation, promoting systemic inflammation and HIV transport into the brain by immune cells; and HIV may compound alcohol's damaging effects on the liver, further increasing inflammation. We additionally review the neurocognitive effects of aging, Hepatitis C coinfection, obesity, and cardiovascular disease, tobacco use, and nutritional deficiencies, all of which have been shown to compound cognitive changes in HIV, AUD, and in their comorbidity. Finally, we examine emerging questions in HIV/AUD research, including genetic and cognitive protective factors, the role of binge drinking in HIV/AUD-linked cognitive decline, and whether neurocognitive and brain functions normalize after drinking cessation.

Inter-trial variability in brain activity as an indicator of synergistic effects of HIV-1 and drug abuse

BACKGROUND

The objective of this investigation was to detect evidence of the synergism in the effects of HIV-1 and drug abuse on brain function that has been hypothesized but rarely shown. The investigation incorporated several noteworthy improvements in the approach. It used urine toxicology tests to exclude participants complicated by recent methadone use and illicit drug use. Also, it defined drug abuse on a scale that considered symptom severity. Most importantly, it examined inter-trial variability in brain activity as a potentially more sensitive indicator of group differences and functional impairment than the across-trial average.

METHODS

173 participants were assigned to groups defined by their HIV-1 serostatus and Drug Abuse Screening Test score (DAST < vs. > = 6). They completed a simple letter discrimination task including rare target and rare nontarget stimuli. Event-related electroencephalographic responses and key press responses were measured on each trial. During a separate assessment, posturographic measures were recorded.

RESULTS

The inter-trial standard deviation of P300-like activity was superior to the mean amplitude of this activity in differentiating the groups. Unlike the mean, it revealed synergistic statistical effects of HIV and drug abuse. It also correlated significantly with static ataxia.

CONCLUSIONS

Inter-trial variability in P300-like activity is a useful marker for detecting subtle and episodic disruptions in brain function. It demonstrates greater sensitivity than the mean amplitude for detecting differences across groups. Also, as a putative indicator of a disruption in the attentional monitoring of behavior, it predicts subtle impairments in gross motor function.

Neuroinflammation and comorbidities are frequently ignored factors in CNS pathology

Virtually all drug interventions that have been successful pre-clinically in experimental stroke have failed to prove their efficacy in a clinical setting. This could be partly explained by the complexity and heterogeneity of human diseases as well as the associated co-morbidities which may render neuroprotective drugs less efficacious in clinical practice. One aspect of crucial importance in the physiopathology of stroke which is not completely understood is neuroinflammation. At the present time, it is becoming evident that subtle, but continuous neuroinflammation can provide the ground for disorders such as cerebral small vessel disease. Moreover, advanced aging and a number of highly prevalent risk factors such as obesity, hypertension, diabetes and atherosclerosis could act as "silent contributors" promoting a chronic proinflammatory state. This could aggravate the outcome of various pathological entities and can contribute to a number of subsequent post-stroke complications such as dementia, depression and neurodegeneration creating a pathological vicious cycle. Moreover, recent data suggests that the inflammatory process might be closely linked with multiple neurodegenerative pathways related to depression. In addition, pro-inflammatory cytokines could play a central role in the pathophysiology of both depression and dementia.

Perfusion deficits, inflammation and aging precipitate depressive behaviour

Major depressive disorder (MDD) is a severe psychiatric illness that is associated with significant morbidity and mortality. Despite advances in the treatment of major depression, one-third of depressed patients fail to respond to conventional antidepressant medication. One pathophysiologic mechanism hypothesized to contribute to treatment resistance in depression is inflammation. Inflammation has been linked to depression by a number of putative mechanisms involving perfusion deficits that can trigger microglial activation and subsequent neuroinflammation in the elderly. However, the pathophysiological mechanisms remain to be further elucidated. This review focusses on recent studies addressing the complex relationships between depression, aging, inflammation and perfusion deficits in the elderly. We expect that a better understanding of neuroinflammatory mechanisms associated with age-related diseases may lead to the discovery of new biomarkers of MDD and development of new therapeutic interventions.

Neural and genetic correlates of binge drinking among college women

Ninety-seven female students were assigned to groups consisting of 55 infrequent and 42 frequent binge drinkers. The groups were compared on self-report measures of impulsivity, sensation seeking, and alexithymia, as well as several measures relevant to neural and genetic mechanisms, such as brain activation during a time estimation task and selected genotypes. Analyses of stimulus-locked brain activity revealed a slow cortical potential over the right parietal cortex during time estimation that was more negative among frequent binge drinkers. This group also showed a greater prevalence of a CHRM2 genotype previously associated with substance dependence and Major Depressive Disorder as well as a modest elevation on a non-planning impulsiveness scale. We conclude that the enhanced brain activation shown by binge drinkers compensates for an underlying deficit. That deficit may be reflected in poor planning skills and a genetic difference indicating increased risk for problems in later life.

An obese body mass increases the adverse effects of HIV/AIDS on balance and gait

BACKGROUND

Balance and gait problems have been detected among patients with HIV/AIDS. The extent to which these problems are exacerbated by either frailty or obesity has not been examined. Objective The purpose of this study was to compare participants who differed in body mass and the presence or absence of HIV/AIDS.

DESIGN

This was a cross-sectional study.

METHODS

Quantitative measurements were obtained from 86 participants who were HIV-type 1 (HIV-1) seronegative and 121 participants who were seropositive divided into subgroups based on their body mass index (BMI <21, 21-29, or >29 kg/m(2)).

RESULTS

Participants who were seropositive were impaired relative to seronegative controls on several indices, including the limit of stability, sway amplitude and sway strategy, gait initiation time, and gait speed during a fast pace condition. Participants who were obese also exhibited impairments, which were evident during assessments of the limit of stability, nonpreferred leg stance time, sway strategy, normal and fast gait speed, fast gait initiation time, and 360-degree turn time. Importantly, the analysis revealed that participants with both attributes were more impaired than those with either or neither attribute: patients who were obese and seropositive were more impaired in fast gait initiation time and cadence, nonpreferred leg stance time, 360-degree turn time, and sway strategy scores. Limitations The validity of BMI as a measure of body mass can be challenged. In addition, the validity of chair rise time and 360-degree turn time as estimates of lower-extremity strength (force-generating capacity) can be argued.

CONCLUSIONS

The present findings have an obvious and unfortunate implication: as more patients who are HIV-1 seropositive join the seronegative community in becoming obese, the effects of obesity and their disease may summate and their risk for balance and gait problems may increase.

Interactive effects of HIV/AIDS, body mass, and substance abuse on the frontal brain: a P300 study

In view of the rising prevalence of an overweight body mass among patients living with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS), clinicians must now be mindful of possible adverse outcomes resulting from the co-occurrence. The present study was designed to examine the additive and interactive effects of HIV/AIDS and an excess body mass, as well as the additional contributions of substance abuse or dependence. The dependent variable was brain function estimated by the measurement of P300 electroencephalographic potentials. P300 potentials were recorded during a task designed to elicit subcomponents with frontal (P300a) and both frontal and non-frontal (P300b) generators. Analyses revealed greater frontal P300a latencies among the 102 HIV-1 seropositive versus the 68 seronegative participants. In addition, frontal P300a latency was further increased by a synergistic interaction of HIV-1 serostatus with a body mass index (BMI)≥25 kg/m². A history of substance abuse/dependence did not alter these changes. However, it did combine with HIV/AIDS to produce a smaller P300a amplitude than was seen in participants with neither disorder. The findings suggest that white matter changes accompanying an excess BMI may exacerbate those that attend HIV/AIDS and thereby slow down frontal brain function. Substance abuse, likewise, interacts with HIV/AIDS but may impair frontal brain function via a different mechanism.

Obesity, smoking, and frontal brain dysfunction

Obesity, smoking, and conduct problems have all been associated with decrements in brain function. However, their additive and interactive effects have rarely been examined. To address the deficiency, we studied P300a and P300b electroencephalographic potentials in 218 women grouped by the presence versus absence of: (1) a BMI > or = 30 kg/m(2); (2) recent smoking; and (3) > or = 2 childhood conduct problems. Analyses revealed smaller P300a and P300b amplitudes over the posterior scalp among recent smokers versus nonsmokers. No corresponding group differences were found in P300 latencies or frontal scalp amplitudes. The most interesting analysis result was an interaction between conduct problems and obesity limited to the frontally generated P300a component: its latency was significantly greater in women with both attributes than in those with either or neither attribute. An exploratory ANOVA, substituting the genotype of a GABRA2 SNP for conduct problems, also demonstrated an interaction with obesity affecting P300a latency. It is hypothesized that conduct problems, and a conduct-problem-associated GABRA2 genotype, decrease the age-of-onset and/or increase the lifetime duration of obesity. As a result, they may potentiate the adverse effects of obesity on frontal white matter and thereby increase P300a latency. Smoking may affect brain function by a different mechanism to reduce posterior scalp P300a and P300b amplitudes while preserving frontal scalp P300a latency and amplitude.

P300 and the stroop effect in overweight minority adolescents

AIM

The goal was to examine the relationship between a risk factor for poor cognitive control and a health outcome of growing public significance--an excess body mass--among adolescents.

METHODS

To this end, 109 adolescents aged 14-20 years were recruited and assigned to 1 of 4 groups defined by the crossing of the absence versus presence of a parental history (PH) of externalizing disorders with a body mass index (BMI) percentile (BMIP) < 85 versus > or = 85. The principal measure estimating cognitive control was the P300 event-related electroencephalographic response recorded during the Stroop task.

RESULTS

The analyses revealed a synergistic interaction between BMIP rank, PH and trial type: the increase in P300 latency and the decrease in response accuracy, elicited by the presence of interfering information, were markedly greater in high-BMIP subjects with a PH of externalizing disorders than in the other subject groups. Analyses of a later component, the N450, previously associated with the Stroop interference effect, revealed no effect of BMI or PH.

CONCLUSIONS

We conclude that subjects with both a PH of externalizing disorders and an excess BMI constitute a unique group that is less able to resolve cognitive conflict than others. The excessive delay in P300 evoked by conflicting response demands in these subjects may be a marker of a heritable factor that increases risk for both excess body mass and substance use disorders.