Biomedical subjects

Eric N Miller

Publications and source records attributed to Eric N Miller.

6 recordsLinked to original sources

PubMed2005

Enlarged striatum in abstinent methamphetamine abusers: a possible compensatory response.

BACKGROUND: Little is known about structural brain abnormalities associated with methamphetamine (METH) abuse; therefore, we aimed: 1) to evaluate possible morphometric changes, especially in the striatum of recently abstinent METH-dependent subjects; 2) to evaluate whether morphometric changes are related to cognitive performance; and 3) to determine whether there are sex-by-METH interactions on morphometry. METHODS: Structural MRI was performed in 50 METH and 50 comparison subjects with the same age range and sex proportion; quantitative morphometric analyses were performed in the subcortical gray matter, cerebellum and corpus callosum. Neuropsychological tests were also performed in 44 METH and 28 comparison subjects. RESULTS: METH users showed enlarged putamen (left: + 10.3%, p = .0007; right: + 9.6%, p = .001) and globus pallidus (left: + 9.3%, p = .002; right: + 6.6%, p = .01). Female METH subjects additionally showed larger mid-posterior corpus callosum (+ 9.7%, p = .05). Although METH users had normal cognitive function, those with smaller striatal structures had poorer cognitive performance and greater cumulative METH usage. CONCLUSIONS: Since METH subjects with larger striatal structures had relatively normal cognitive performance and lesser cumulative METH usage, the enlarged putamen and globus pallidus might represent a compensatory response to maintain function. Possible mechanisms for the striatal enlargement include glial activation and inflammatory changes associated with METH-induced injury.

Adult↗

PubMed2004

Regional patterns of brain metabolites in AIDS dementia complex.

The relationship of the cellular changes in the HIV-infected brain to the onset and progression of AIDS dementia complex (ADC) remains uncertain. We undertook an in vivo proton magnetic resonance spectroscopy (MRS) study and used factor analysis to identify specific cellular and regional brain changes that may serve as metabolic markers of ADC. The ratio of N-acetyl aspartate (NAA), choline (Cho), and myoinositol (MI) over creatine (Cr), markers of neuronal and glial cell metabolism, were measured in the basal ganglia, centrum semiovale, and parietal cortex from 100 subjects with and without ADC. Three metabolic patterns were identified, which we termed "inflammatory" (mainly MI/Cr elevations in all three regions plus Cho/Cr increases in the centrum semiovale and parietal cortex), "basal ganglia" (mostly NAA/Cr and Cho/Cr elevations in the basal ganglia), and "neuronal" (primarily NAA/Cr reductions in the centrum semiovale and the parietal cortex). Logistic regression analysis revealed that, adjusted for age, basal ganglia and neuronal pattern scores were strongly associated with ADC but inflammatory levels were not. We conclude that by using factor analysis, we are able to combine multiple metabolites across brain regions in a biologically plausible manner and construct a predictive model of ADC adjusting for relevant factors such as age.

AIDS Dementia Complex↗

PubMed2004

Normative data for determining significance of test-retest differences on eight common neuropsychological instruments.

Clinicians and researchers who use neuropsychological tests to track functioning over time are in need of a method to correct for the effects of practice. Drawing from a large database of healthy, male subjects, we present data that can be used to calculate predicted retest scores for eight widely used neuropsychological instruments either via simple regression or reliable change index (RCI) methods. These methods are useful for individuals assessed across a wide time interval, 4-24 months. Limitations are discussed regarding the applicability of the data. Those with a need to factor out the effects of practice, test-retest reliability and other statistical confounds will find the information within this article useful.

Adult↗

PubMed2003

Psychosocial risk factors of HIV morbidity and mortality: findings from the Multicenter AIDS Cohort Study (MACS).

Despite the use of laboratory markers in estimating HIV prognosis, significant variation in the natural history of HIV-1 infection remains unexplained. Recent studies suggest psychosocial risk factors have important prognostic significance in HIV disease. The objective of the present study was to examine the prognostic influence of age, general intellectual functioning, and emotional distress across the spectrum of HIV disease progression. The study sample was drawn from the Multicenter AIDS Cohort Study (MACS), a 13-year, prospective study of HIV-seropositive men recruited from four study centers across the country. The participants were 1,231 HIV-seropositive MACS participants, followed from baseline (median 8/15/87) to the end of the observation period (12/15/98). HIV disease progression was evaluated with respect to three outcome measures: (1) number of years from baseline testing to the first AIDS defining illness (progression to AIDS), (2) years from baseline to HIV-dementia (progression to dementia), and (3) years from baseline to death (survival). The influence of psychosocial risk factors on outcome measures was evaluated using survival analyses. General intellectual functioning, age, and somatic symptoms of depression, were found to be significant predictors of HIV disease progression and survival. Older age at baseline was associated with a more rapid progression to dementia and death. Lower Shipley IQ estimates were associated with a more rapid disease progression (AIDS and dementia) and shortened survival. Somatic symptoms of depression were associated with shortened survival. In addition, age, IQ, and somatic symptoms of depression, had an additive effect with an increase in the number of risk factors associated with accelerated disease progression and shortened time to death. These findings remained consistent, despite controlling for baseline CD4 and HIV medication use. Psychosocial cofactors are important in understanding HIV disease progression. Methods for estimating HIV prognosis may become more reliable if psychosocial factors are considered. Future research will clarify if psychosocial risk factors reflect central nervous system integrity, brain reserve capacity or mediate morbidity and mortality through social economic status, access to health care and other social correlates.

AIDS Dementia Complex↗

PubMed2003

Persistent brain abnormalities in antiretroviral-naive HIV patients 3 months after HAART.

BACKGROUND: Proton magnetic resonance spectroscopy (1H-MRS) and neuropsychological tests may be useful for monitoring the effectiveness of highly active antiretroviral therapy (HAART) in HIV-associated brain injury. We aimed to evaluate whether brain abnormalities will improve 3 months after HAART. METHOD: Thirty-three HIV patients naive to antiretroviral medications were evaluated before and 3 months after HAART using 1H-MRS and neuropsychological tests; results were compared with those of 26 seronegative control subjects. RESULTS: Despite significant improvement in CD4 counts, and suppression of plasma and cerebrospinal fluid (CSF) viral loads, elevated brain metabolites (choline compounds and myoinositol in the frontal lobes) and neuropsychological tests abnormalities (including the computerized tests [CalCAP]) persisted after 3 months of HAART. In the basal ganglia, choline and myoinositol became elevated only after treatment. No interaction effect was observed between the number of CSF-penetrating drugs (one vs two) and changes (baseline vs 3 months) in any of the brain metabolites, cognitive performance or CSF viral load. CONCLUSIONS: The persistent brain abnormalities suggest ongoing repair or reactive inflammatory processes in the brain after 3 months of HAART. Regimens with two CSF-penetrating antiretroviral medications do not appear to be more effective than those with one CSF-penetrating drug in treating HIV brain injury at 3 months.

AIDS Dementia Complex↗

PubMed2002

Perfusion MRI and computerized cognitive test abnormalities in abstinent methamphetamine users.

This study aims to determine possible persistent abnormalities in regional cerebral blood flow (relative rCBF) and cognitive function in abstinent methamphetamine (METH) users. Twenty METH-dependent subjects (abstinent for 8+/-2 months) and 20 age- and gender-matched controls were evaluated with perfusion magnetic resonance imaging (pMRI) and neuropsychological tests. METH users showed decreased relative rCBF bilaterally in putamen/insular cortices (right: -12%; left: -10%) and the right lateral parietal brain region (-11%), but increased relative rCBF bilaterally in the left temporoparietal white matter (+13%), the left occipital brain region: (+10%) and the right posterior parietal region (+24%). Interaction effects were observed between METH and gender in the right occipital cortex and a midline brain region; female METH users showed increased relative rCBF (+15% both regions) whereas the male METH users had decreased relative rCBF (-10% and -18%, respectively). METH users performed within normal ranges on standard neuropsychological tests; however, they were slower on several tasks on the California Computerized Assessment Package (CalCAP), especially tasks that required working memory. These findings suggest that METH abuse is associated with persistent physiologic changes in the brain, and these changes are accompanied by slower reaction times on computerized measures of cognitive function.

Adult↗