Biomedical subjects

H A Wishart

Publications and source records attributed to H A Wishart.

7 recordsLinked to original sources

PubMed2006

Regional brain atrophy in cognitively intact adults with a single APOE epsilon4 allele.

OBJECTIVE: To determine whether cognitively intact adults with the APOE epsilon3/epsilon4 genotype show reduced gray matter density on voxel-based morphometry (VBM) vs those homozygous for the epsilon3 allele. METHODS: Participants were healthy, cognitively intact, right-handed adults, age 19 to 80, who completed genotyping, neuropsychological testing, and MRI. Forty-nine participants had the epsilon3/epsilon3 genotype and 27 had the epsilon3/epsilon4 genotype. Gray matter data were analyzed using the general linear model as implemented in the Statistical Parametric Mapping package, adjusting for age and sex. RESULTS: The epsilon3/epsilon4 participants showed lower gray matter density than the epsilon3/epsilon3 participants in right medial temporal and bilateral frontotemporal regions as well as other areas. There were no regions in which epsilon3/epsilon4 participants showed higher gray matter density than epsilon3/epsilon3 participants. CONCLUSIONS: Regionally reduced gray matter density is detectable in cognitively intact adults with a single copy of the APOE epsilon4 allele.

Adult↗

PubMed2006

Older adults with cognitive complaints show brain atrophy similar to that of amnestic MCI.

OBJECTIVE: To examine the neural basis of cognitive complaints in healthy older adults in the absence of memory impairment and to determine whether there are medial temporal lobe (MTL) gray matter (GM) changes as reported in Alzheimer disease (AD) and amnestic mild cognitive impairment (MCI). METHODS: Participants were 40 euthymic individuals with cognitive complaints (CCs) who had normal neuropsychological test performance. The authors compared their structural brain MRI scans to those of 40 patients with amnestic MCI and 40 healthy controls (HCs) using voxel-based morphometry and hippocampal volume analysis. RESULTS: The CC and MCI groups showed similar patterns of decreased GM relative to the HC group on whole brain analysis, with differences evident in the MTL, frontotemporal, and other neocortical regions. The degree of GM loss was associated with extent of both memory complaints and performance deficits. Manually segmented hippocampal volumes, adjusted for age and intracranial volume, were significantly reduced only in the MCI group, with the CC group showing an intermediate level. CONCLUSIONS: Cognitive complaints in older adults may indicate underlying neurodegenerative changes even when unaccompanied by deficits on formal testing. The cognitive complaint group may represent a pre-mild cognitive impairment stage and may provide an earlier therapeutic opportunity than mild cognitive impairment. MRI analysis approaches incorporating signal intensity may have greater sensitivity in early preclinical stages than volumetric methods.

Aged↗

PubMed2004

Brain activation patterns associated with working memory in relapsing-remitting MS.

BACKGROUND: Patients with multiple sclerosis (MS) show changes in brain activation patterns during visual and motor tasks that include decreases in the typical local network for a function and increases in other brain regions. OBJECTIVE: To determine whether brain activation patterns associated with working memory are affected by MS. METHODS: Activation of working memory circuitry was examined using an fMRI n-back task in adults with mild relapsing-remitting MS (RRMS; n = 10) and demographically matched healthy controls (n = 10). RESULTS: Group differences in brain activation emerged during both low- and high-demand conditions (p < 0.001). Overall, patients showed less activation than controls in core prefrontal and parietal regions of working memory circuitry, and greater activation in other regions within and beyond typical working memory circuitry, including bilateral medial frontal, cingulate, parietal, bilateral middle temporal, and occipital regions. CONCLUSIONS: Relative to controls, patients with mild RRMS showed shifts in brain activation patterns within and beyond typical components of working memory circuitry.

Adult↗

PubMed2003

Sex differences in semantic language processing: a functional MRI study.

Predictions based on two models of sex differences in cerebral organization of language were compared by examining fMRI patterns of 10 females and 9 males during a semantic processing task. Both groups displayed activation of left inferior frontal gyrus (IFG), left superior temporal gyrus (STG), and cingulate. Females, but not males, showed bilateral IFG and STG activation. Further analyses revealed females had less diffuse left activation and greater right posterior temporal and insula region activation than males. Results support both an interhemispheric and an intrahemispheric model of sex differences in language, suggesting that the models may not be mutually exclusive.

Brain↗

PubMed2003

Chronic deep brain stimulation for the treatment of tremor in multiple sclerosis: review and case reports.

BACKGROUND: Deep brain stimulation (DBS) offers a non-ablative alternative to thalamotomy for the surgical treatment of medically refractory tremor in multiple sclerosis. However, relatively few outcomes have been reported. OBJECTIVE: To provide a systematic review of the published cases of DBS use in multiple sclerosis and to present four additional patients. METHODS: Quantitative and qualitative review of the published reports and description of a case series from one centre. RESULTS: In the majority of reported cases (n=75), the surgical target for DBS implantation was the ventrointeromedial nucleus of the thalamus. Tremor reduction and improvement in daily functioning were achieved in most patients, with 87.7% experiencing at least some sustained improvement in tremor control postsurgery. Effects on daily functioning were less consistently assessed across studies; in papers reporting relevant data, 76.0% of patients experienced improvement in daily functioning. Adverse effects were similar to those reported for DBS in other patient populations. CONCLUSIONS: Few of the studies reviewed used highly standardised quantitative outcome measures, and follow up periods were generally one year or less. Nonetheless, the data suggest that chronic DBS often produces improved tremor control in multiple sclerosis. Complete cessation of tremor is not necessarily achieved, there are cases in which tremor control decreases over time, and frequent reprogramming appears to be necessary.

Adult↗

PubMed2001

The neuropsychology of multiple sclerosis: contributions of neuroimaging research.

Multiple sclerosis (MS) is often associated with cognitive and emotional changes that affect daily activities and quality of life. Deficits in memory, executive function, processing speed, and other cognitive domains are frequently reported. In addition, mood disturbances and fatigue are common. In this article, the authors highlight research on individual differences in the neuropsychology of MS, and emphasize neuroimaging studies that help elucidate the basis of the deficits.

Brain↗

PubMed1995

Interhemispheric transfer in multiple sclerosis.

Interhemispheric transfer (IHT) was investigated in patients with multiple sclerosis (n = 20) and healthy control subjects (n = 23). On verbal dichotic listening and tachistoscopic reading tests, MS patients showed a pattern of left-sided suppression and/or right-sided enhancement, consistent with impairment of IHT. Patients with chronic-progressive MS were most affected. Clinical and empirical implications are noted.

Adult↗