Biomedical subjects

Brian Bell

Publications and source records attributed to Brian Bell.

16 recordsLinked to original sources

PubMed2007

Neuropsychological effects of bilateral deep brain stimulation of the subthalamic nucleus in Parkinson's disease.

OBJECTIVE: Although a relatively new technique, bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) for the treatment of advanced cases of Parkinson's disease (PD) shows considerable promise. While the benefits of the STN stimulation for the treatment of motor symptoms of PD are well established, some studies have reported negative neuropsychological outcomes, especially in elderly patients. The objective of the present study was to investigate the neuropsychological effects of bilateral STN-DBS in a small sample of elderly patients with PD. METHODS: Six patients with PD (mean age 73.0 +/- 10.45 years) were assessed both before and approximately 6 months after DBS surgery in six neuropsychological domains. These domains included orientation, estimated IQ, attention/working memory, language, memory, and visual-spatial functioning. Additionally, depressive symptoms were assessed using the Geriatric Depression Scale. Daily doses of antiparkinsonian medications, in levodopa equivalents, were also compared pre- and postoperatively. RESULTS: Antiparkinsonian medications were reduced postoperatively by a mean of 65%, from a mean levodopa equivalent dosage of 987 mg/day to 346 mg/day. Category fluency, a word generation task within the language domain, was the only test in which participants demonstrated a statistically significant decline in performance. Participants demonstrated a mean score decrease of 41% (p < 0.05) in category fluency. CONCLUSIONS: The pathophysiology of the observed deficit remains ill defined. However, despite a small sample size, the study provides further evidence that bilateral STN-DBS in PD patients can be associated with negative neuropsychological outcome in word fluency, especially in elderly patients. Implications regarding patient selection for bilateral STN-DBS and recommendations for future research are further discussed.

Aged↗

PubMed2006

Socioeconomic risk, parenting during the preschool years and child health age 6 years.

BACKGROUND: Parent child relationships and parenting processes are emerging as potential life course determinants of health. Parenting is socially patterned and could be one of the factors responsible for the negative effects of social inequalities on health, both in childhood and adulthood. This study tests the hypothesis that some of the effect of socioeconomic risk on health in mid childhood is transmitted via early parenting. METHODS: Prospective cohort study in 10 USA communities involving 1041 mother/child pairs, selected at birth at random with conditional sampling. EXPOSURES: income, maternal education, maternal age, lone parenthood, ethnic status and objective assessments of mother child interaction in the first 4 years of life covering warmth, negativity and positive control. OUTCOMES: mother's report of child's health in general at 6 years. Modelling: multiple regression analyses with statistical testing of mediational processes. RESULTS: All five indicators of socioeconomic status (SES) were correlated with all three measures of parenting, such that low SES was associated with poor parenting. Among the measures of parenting maternal warmth was independently predictive of future health, and among the socioeconomic variables maternal education, partner presence and 'other ethnic group' proved predictive. Measures of parenting significantly mediated the impact of measures of SES on child health. CONCLUSIONS: Parenting mediates some, but not all of the detectable effects of socioeconomic risk on health in childhood. As part of a package of measures that address other determinants, interventions to support parenting are likely to make a useful contribution to reducing childhood inequalities in health.

Analysis of Variance↗

PubMed2006

Cognitive prognosis in chronic temporal lobe epilepsy.

OBJECTIVE: First, to determine whether patients with chronic temporal lobe epilepsy have a different cognitive trajectory compared to control subjects over a prospective 4-year interval; second, to determine the proportion of patients who exhibit abnormal cognitive change and their profile of demographic, clinical epilepsy, and baseline quantitative magnetic resonance imaging characteristics; and third, to determine the most vulnerable cognitive domains. METHODS: Participants with chronic temporal lobe epilepsy (n = 46) attending a tertiary referral clinic and healthy control subjects (n = 65) underwent neuropsychological assessment and reevaluation 4 years later. Analysis of test-retest patterns identified individual patients with adverse cognition outcomes. RESULTS: The prospective cognitive trajectory of patients with chronic temporal lobe epilepsy differs from age- and sex-matched healthy control subjects. Lack of practice effects is common, but frank adverse cognitive outcomes are observed in a subset of patients (20-25%), particularly in vulnerable cognitive domains that include memory. Cognitive declines are associated with a profile of abnormalities in baseline quantitative magnetic resonance volumetrics, lower baseline intellectual capacity, as well as longer duration of epilepsy and older chronological age. INTERPRETATION: Cognitive prognosis is poor for a subset of patients characterized by chronicity of epilepsy, older age, lower intellectual ability, and more baseline abnormalities in quantitative magnetic resonance volumetrics.

Adolescent↗

PubMed2006

Memory for famous faces and the temporal pole: functional imaging findings in temporal lobe epilepsy.

The ability to recognize, name, and provide information about famous persons is deficient in patients with temporal lobe epilepsy (TLE), although the neural basis for these deficits is not well understood. We examined the relationship of resting metabolism of the temporal poles, as determined by [18F] fluorodeoxyglucose positron emission tomography, to performance on a task of famous face recognition, naming, and generation of semantic information in 12 patients with TLE. Correlations between metabolic measures of the temporal poles and performance on the Famous Faces Task revealed strong relationships between all aspects of the Famous Faces Task and the left temporal pole, whereas Famous Faces Task correlations with the right temporal pole were not significant. These findings indicate that the left temporal pole is associated with lexical and semantic retrieval of knowledge of famous persons in patients with TLE. Further study appears warranted to elucidate the networks involved in semantic knowledge for famous faces.

Adolescent↗

PubMed2004

Quantitative measurement of cortical surface features in localization-related temporal lobe epilepsy.

Differences in cortical surface features between healthy controls (n = 48) and patients with temporal lobe epilepsy (n = 46), ages 14-59, were characterized by means of advanced quantitative MRI processing techniques. Cortical surface features of interest included gyral and sulcal curvature, cortical depth, and total cortical surface area. Epilepsy patients and controls differed on measures of gyrification; the abnormalities generalized despite the focal nature of the primary epileptic process. Changes in cortical surface features were associated with increasing chronological age in both groups. Abnormalities in gyrification were associated with cognitive performance and with other morphometric measurements (e.g., surface cerebral spinal fluid). These findings are related to the literature regarding morphometric changes associated with temporal lobe epilepsy and normal aging.

Adolescent↗

PubMed2003

Epilepsy surgery outcome among US veterans.

We retrospectively studied the outcome of anterior temporal lobectomy (ATL) among a population of veterans and evaluated outcome related to comorbidities. Veterans who underwent ATL between 1990 and 2001 at the Veterans Administration Hospital in Madison, Wisconsin, were included. Data related to postoperative seizure outcome, quality of life outcome, and employment outcome were collected. Factors associated with favorable outcome and outcome related to comorbidities were evaluated. Twenty-seven patients were entered into the study. The mean age at onset of seizures was 25 years (+/-10.2). History of a non-substance abuse psychiatric diagnosis, and substance abuse was present in 26% (7/27) and 30% (9/27), respectively, prior to surgery. While 66.6% (18/27) had a good outcome (Engel's Class I), no difference in the frequency of good outcome was seen among the patients with a history of substance abuse, other psychiatric diagnosis (71%), or no psychiatric diagnosis (67%). There was a significant correlation between seizure outcome and quality of life score (r(s)=0.67, p<0.001) and postoperative employment gains (r(s)=0.48, p=0.01). Outcomes among veterans that underwent ATL can be satisfactory even in the context of the late mean age of epilepsy onset and the psychiatric diagnoses that were present in this sample.

Adult↗

PubMed2003

Negative symptoms and psychosocial status in temporal lobe epilepsy.

PURPOSE: To determine the relationship between negative symptoms, psychosocial function and quality of life in temporal lobe epilepsy. METHODS: 23 patients with temporal lobe epilepsy with negative symptoms were matched on gender, age, years of education, duration and age of epilepsy onset with 23 temporal lobe epilepsy patients exhibiting no negative symptoms as determined by a standardized rating system (SANS/SAPS). The matched groups were compared in regard to: (1). employment status, (2). dependence on government financial subsidy, (3). relationship/marital status, and (4). self-reported quality of life. RESULTS: Temporal lobe epilepsy patients with negative symptoms exhibited higher rates of unemployment, dependence on government aid, social isolation, and poorer self-reported quality of life relative to temporal lobe patients without negative symptoms. CONCLUSIONS: Interictal negative symptoms are associated with significantly increased psychosocial morbidity and poorer quality of life in temporal lobe epilepsy.

Adult↗

PubMed2003

Extratemporal quantitative MR volumetrics and neuropsychological status in temporal lobe epilepsy.

Neuropsychological studies of temporal lobe epilepsy have focused heavily on the nature and extent of memory dysfunction and its relationship to the neuropathological status of the hippocampus and related mesial temporal lobe structures. In this study, we examined whole brain and lobar quantitative MRI volumes and comprehensive neuropsychological performance in 58 patients with temporal lobe epilepsy and 62 healthy controls in order to determine (1) the nature and degree of extratemporal structural abnormalities in localization-related temporal lobe epilepsy: (2) the nature and degree of cognitive abnormalities outside of anterograde memory function; and (3) the relationship of volumetric abnormalities to neuropsychological status. Temporal lobe epilepsy patients exhibited significant reduction in the volume of adjusted (age, gender, height) total cerebral tissue (-5.8%), more evident in white (-9.8%) compared to gray matter (-3.0%) tissue volumes. Significant volumetric reductions were evident across frontal, temporal and parietal but not occipital lobe regions. Subarachnoid but not total ventricular CSF was significantly increased in epilepsy patients. Neuropsychological abnormality was generalized in nature, consistent with the generalized nature of the morphometric abnormalities, and reductions in cerebral tissue volumes were directly associated with poorer cognitive performance. In summary, patients with temporal lobe epilepsy exhibited clinically significant structural and functional abnormalities that extended outside the epileptogenic temporal lobe. The degree to which these structural and cognitive abnormalities are due to factors that cause the epilepsy, as opposed to reflecting the consequences of chronic epilepsy (e.g., duration and severity of epilepsy), remain to be determined.

Adolescent↗

PubMed2003

Narrative and procedural discourse in temporal lobe epilepsy.

It is well established that some individuals with temporal lobe epilepsy (TLE) demonstrate language deficits at the single word level. However, discourse production rarely has been examined quantitatively within this group. This study compared adult TLE patients with an early seizure onset (< or = age 14 years, n = 27) to a control group (n = 28) on narrative and procedural discourse tasks. As a group, the TLE patients performed normally on the procedural discourse task, but differed significantly from the controls on several narrative discourse variables. At the individual level, 30% of the TLE patients versus 4% of the controls demonstrated impaired discourse ability (p and 0.01). Within this early onset TLE group, discourse performance was not associated with demographic or seizure history variables. Considering the cognitive domain, discourse performance correlated significantly with working memory. In summary, mild discourse dysfunction was present in a significant minority of early onset TLE patients, but this deficit was not closely associated with other language measures. Discourse ability and its neuropsychological, neuroanatomical and conversational speech correlates deserve further study in TLE patients.

Adolescent↗

PubMed2003

A controlled quantitative MRI volumetric investigation of hippocampal contributions to immediate and delayed memory performance.

MRI volumetric TLE studies show inconsistent evidence of hippocampal involvement in memory. Prior studies have not dissociated hippocampal and temporal lobe contributions to memory. We measured hippocampal and temporal lobe volumes and immediate/delayed memory performances in 64 TLE patients. Regression was used to dissociate hippocampal from temporal lobe contributions to memory. Results revealed reliable evidence for dominant hippocampal involvement in delayed verbal recall across three separate measures and less consistent evidence for nondominant hippocampal involvement. The findings point to a consistent relationship of dominant hippocampal volumes to delayed verbal recall but no involvement of the temporal lobe or nondominant hippocampus in memory.

Adolescent↗

PubMed2002

Ipsilateral Reorganization of Language in Early-Onset Left Temporal Lobe Epilepsy.

Purpose. Decline in confrontation naming ability occurs in a subset of temporal lobe epilepsy (TLE) patients following left (dominant) anterior temporal lobectomy (ATL). Patients with late age of onset of seizures are most vulnerable to such decline. In addition, object names typically acquired later in language development are the words most likely to be inaccessible after ATL. Early-onset left TLE patients may be at lower risk for post-ATL dysnomia either because they have a limited preoperative lexicon that does not include most late-age-of-acquistion names or they undergo early ipsilateral language reorganization, which results in a lexicon similar to that of late-onset TLE patients but offers protection from post-ATL naming decline.Methods. Sixty-five left hemisphere speech dominant left TLE patients who had undergone ATL were assessed pre- and postoperatively on the Boston Naming Test (BNT).Results. The early- and late-onset groups performed similarly across three BNT age-of-acquisition categories at the preoperative assessment. Words acquired relatively later in life were most likely to become inaccessible postoperatively for both groups, but the early-onset patients showed significantly less overall postoperative decline in naming ability compared with the late-onset group.Conclusions. The more stable pre- to postoperative naming performance exhibited by early-onset patients cannot be attributed to lack of acquisition of the words shown to be most vulnerable to postoperative decline (i.e., late-age-of-acquisition words). Their object naming stability suggests that early-onset left TLE patients undergo intrahemispheric reorganization of language early in life that provides protective benefits.

Journal Article↗

PubMed2002

Recognition and identification of famous faces in patients with unilateral temporal lobe epilepsy.

We examined the performance of 21 patients with unilateral temporal lobe epilepsy (TLE) and hippocampal damage (10 lefts, and 11 rights) and 10 age-matched controls on the recognition and identification (name and occupation) of well-known faces. Famous face stimuli were selected from four time periods; 1970s, 1980s, 1990-1994, and 1995-1996. Differential patterns of performance were observed for the left and right TLE group across distinct face processing components. The left TLE group showed a selective impairment in naming famous faces while they performed similar to the controls in face recognition and semantic identification (i.e. occupation). In contrast, the right TLE group was impaired across all components of face memory; face recognition, semantic identification, and face naming. Face naming impairment in the left TLE group was characterized by a temporal gradient with better naming performance for famous faces from more distant time periods. Findings are discussed in terms of the role of the temporal lobe system for the acquisition, retention, and retrieval of face semantic networks, and the differential effects of lateralized temporal lobe lesions in this process.

Adult↗

PubMed2002

The neurodevelopmental impact of childhood onset temporal lobe epilepsy on brain structure and function and the risk of progressive cognitive effects.

The purpose of this study is to explore the possibility of progressive neuropsychological decline in chronic temporal lobe epilepsy (TLE) and determine how this vulnerability may be associated with the neurodevelopmental impact of the disorder. 53 patients with TLE and 62 healthy controls underwent quantitative MRI volumetric imaging of total brain tissue and hippocampal volumes as well as assessment of intelligence and memory function. In addition to reduced hippocampal volume, childhood onset (< 14 years) but not adult onset TLE was associated with significantly reduced total brain tissue that was generalized in nature and extended into extratemporal regions. In addition to this adverse impact on brain structure, there was significantly reduced intellectual status as well as memory function in childhood onset TLE patients, consistent with the generalized nature of the MRI volumetric abnormalities. Finally, cross-sectional correlational analyses indicated that increasing duration of epilepsy in childhood onset patients was associated with declining performance across both intellectual and memory measures, suggestive of progressive cognitive effects. We propose that childhood onset TLE is associated with an adverse neurodevelopmental impact on brain structure and function which represents an early acquired vulnerability, effectively reducing cerebral reserve, placing patients at risk for progressive cognitive decline in the context of chronic and unremitting epilepsy.

Age of Onset↗

PubMed2002

The neurodevelopmental impact of childhood-onset temporal lobe epilepsy on brain structure and function.

PURPOSE: To characterize the neurodevelopmental correlates of childhood-onset temporal lobe epilepsy on brain structure and cognition compared with late-onset chronic temporal lobe epilepsy and healthy controls. METHODS: Healthy controls (n = 62) and patients with early (n = 37) versus late (n = 16) age at onset of temporal lobe epilepsy were compared with high-resolution quantitative magnetic resonance imaging (MRI) volumetrics and comprehensive neuropsychological assessment. RESULTS: Patients with childhood-onset temporal lobe epilepsy (mean onset age, 7.8 years) exhibited widespread compromise in neuropsychological performance and substantial reduction in brain tissue volumes extending to extratemporal regions compared with healthy controls and late-onset temporal lobe epilepsy patients (mean onset age, 23.3 years). Most evident was reduced total white-matter volume among the childhood-onset patients. Reduction in brain tissue volume, especially total white-matter volume, was associated with significantly poorer cognitive status, attesting to the clinical significance of the volumetric abnormalities. CONCLUSIONS: Childhood-onset temporal lobe epilepsy appears to be associated with an adverse neurodevelopmental impact on brain structure and cognition that appears generalized in nature and especially evident in white-matter tissue volume.

Adolescent↗

PubMed2002

Cr supplementation decreases tyrosine phosphorylation of the CreaT in skeletal muscle during sepsis.

Myocellular creatine (Cr) uptake is predominantly governed by a sodium-dependent Cr transporter (CreaT) and plays a pivotal role in skeletal muscle energy metabolism. The CreaT belongs to a neurotransmitter transporter family that can be functionally regulated by protein tyrosine kinase-induced tyrosine phosphorylation. The association between myocellular Cr and c-Src-related tyrosine phosphorylation of the CreaT and the influence of oral Cr supplementation on this association were investigated during sepsis. Animals were randomized to receive standard rat chow or standard rat chow with oral Cr supplementation for 4 days followed by cecal ligation and puncture (CLP) or sham operation. Fast-twitch gastrocnemius muscles were harvested 24 h after operation. Myocellular free Cr levels were 70% higher after CLP. Western blotting of the immunoprecipitated CreaT with an anti-phosphotyrosine or anti-phospho-c-Src (Y-416) antibody revealed that tyrosine phosphorylation of the CreaT and tyrosine-phosphorylated c-Src (Tyr(416)) expression in the CreaT-c-Src complex were significantly increased after CLP compared with sham operation. These changes were observed in homogenates and plasma membrane fractions of gastrocnemius muscles. Although oral Cr supplementation increased myocellular free Cr levels equivalently in CLP and sham-operated animals, c-Src-related tyrosine phosphorylation of the CreaT in homogenates and plasma membrane fractions of gastrocnemius muscles was, however, downregulated in Cr-supplemented CLP animals compared with Cr-supplemented sham-operated rats. During sepsis, increased myocellular free Cr levels are associated with enhanced tyrosine phosphorylation of the CreaT, which is likely induced by active c-Src. Oral Cr supplementation downregulates c-Src-related tyrosine phosphorylation of the CreaT. The data suggest that myocellular Cr homeostasis and CreaT activity are tightly regulated and closely related during sepsis.

Administration, Oral↗

PubMed2002

Negative symptoms in temporal lobe epilepsy.

OBJECTIVE: This study examined the frequency of negative and positive symptoms in nonpsychotic patients with temporal lobe epilepsy and the relationship of negative and positive symptoms to cognition, quantitative magnetic resonance imaging (MRI) volumetrics, and depression. METHOD: Eighty-four patients with temporal lobe epilepsy and 74 healthy comparison subjects were evaluated for negative and positive symptoms and underwent comprehensive neuropsychological evaluation, quantitative MRI volumetrics, and assessment of mood state and depression. RESULTS: Negative symptoms were significantly more prevalent in the patients with temporal lobe epilepsy (31%) than in the comparison subjects (8%). There was no difference between groups in the rate of positive symptoms. Although the epilepsy patients as a group exhibited generalized cognitive impairment relative to the comparison subjects, the epilepsy patients with negative symptoms performed significantly worse than patients without negative symptoms and comparison subjects across measures of nonverbal intelligence, visuoperception, speeded visuomotor processing, and memory. The epilepsy patients with negative symptoms exhibited significantly greater diffuse atrophy than the healthy comparison subjects and higher CSF volumes than the epilepsy patients without negative symptoms. The epilepsy patients with and without negative symptoms had statistically equivalent Beck Depression Inventory scores and lifetime history of mood disorders, including major depression. CONCLUSIONS: Negative but not positive symptoms were more prevalent in temporal lobe epilepsy patients than in healthy comparison subjects. Negative symptoms were independent of current and past depression and were associated with neuropsychological deficits exceeding the general cognitive morbidity associated with temporal lobe epilepsy and with quantitative MRI indices suggesting greater cerebral atrophy.

Adolescent↗