Biomedical subjects

Christian Dow

Publications and source records attributed to Christian Dow.

10 recordsLinked to original sources

PubMed2006

Children with new-onset epilepsy: neuropsychological status and brain structure.

Abnormalities in cognition, academic performance and brain volumetrics have been reported in children with chronic epilepsy. The nature and degree to which these problems may be present at epilepsy onset or may instead become more evident over time remains to be determined. This study characterizes neuropsychological status, brain structure and their interrelationship in children with recent-onset epilepsy compared with healthy controls. Children (age: 8-18 years) with recent-onset idiopathic epilepsy (n = 53) and healthy controls (n = 50) underwent comprehensive neuropsychological assessment and quantitative volumetric measurement of segmented (grey and white matter) volumes of total cerebrum and lobar regions. Compared with controls, children with recent-onset epilepsy exhibit a pattern of mild diffuse cognitive impairment, regardless of epilepsy syndrome, as well as academic underachievement that in a subset of children antedates the first recognized seizure. There are no overall differences in MR morphometric analyses of total cerebral or lobar tissue volumes. Controls show a strong association between cognitive development and increasing cerebral tissue volume (especially white matter volume), an association that is absent in children with epilepsy. Children with a history of academic achievement problems exhibit the most abnormal cognitive function and have significant volumetric reductions in left occipital and parietal lobe grey matter. Patients with idiopathic epilepsy exhibit cognitive dysfunction and academic underachievement at the onset of the disorder, irrespective of epilepsy syndrome, and indications of antecedent neurocognitive impairment are present in a subset of children. Volumetric abnormalities are not yet apparent in the epilepsy group as a whole, but there are indications of an altered structure-function relationship in epilepsy, and the subset of children with prior history of academic problems have abnormal volume of posterior left hemisphere grey matter. These early abnormalities need to be integrated into lifespan models of the neuropsychology of epilepsy.

Adolescent↗

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↗

PubMed2005

Temporal lobe epilepsy and the selective reminding test: the conventional 30-minute delay suffices.

Conventional memory assessment may fail to identify memory dysfunction characterized by intact recall for a relatively brief period but rapid forgetting thereafter. This study assessed learning and retention after 30-min and 24-hr delays on auditory and visual selective reminding tests (SRTs) in right (n=20) and left (n=22) temporal lobe epilepsy (TLE) patients and controls (n=49). The left TLE group performed significantly worse than controls on all 3 trials of both tests. The right TLE group differed from the controls on all 3 visual SRT trials and on learning for the auditory SRT. There were no between-groups differences in rate of information lost at the 30-min versus the 24-hr delay. At the individual level, there was no difference in the percentage of patients versus controls who demonstrated isolated memory impairment at the 24-hr delay. Accelerated forgetting over 24 hr is uncommon in TLE patients.

Adolescent↗

PubMed2005

Ipsilateral and contralateral MRI volumetric abnormalities in chronic unilateral temporal lobe epilepsy and their clinical correlates.

PURPOSE: To assess the presence, extent, and clinical correlates of quantitative MR volumetric abnormalities in ipsilateral and contralateral hippocampus, and temporal and extratemporal lobe regions in unilateral temporal lobe epilepsy (TLE). METHODS: In total, 34 subjects with unilateral left (n = 15) or right (n = 19) TLE were compared with 65 healthy controls. Regions of interest included the ipsilateral and contralateral hippocampus as well as temporal, frontal, parietal, and occipital lobe gray and white matter. Clinical markers of neurodevelopmental insult (initial precipitating insult, early age of recurrent seizures) and chronicity of epilepsy (epilepsy duration, estimated number of lifetime generalized seizures) were related to magnetic resonance (MR) volume abnormalities. RESULTS: Quantitative MR abnormalities extend beyond the ipsilateral hippocampus and temporal lobe with extratemporal (frontal and parietal lobe) reductions in cerebral white matter, especially ipsilateral but also contralateral to the side of seizure onset. Volumetric abnormalities in ipsilateral hippocampus and bilateral cerebral white matter are associated with factors related to both the onset and the chronicity of the patients' epilepsy. CONCLUSIONS: These cross-sectional findings support the view that volumetric abnormalities in chronic TLE are associated with a combination of neurodevelopmental and progressive effects, characterized by a prominent disruption in ipsilateral hippocampus and neural connectivity (i.e., white matter volume loss) that extends beyond the temporal lobe, affecting both ipsilateral and contralateral hemispheres.

Adolescent↗

PubMed2004

Relationship between information processing speed in temporal lobe epilepsy and white matter volume.

Abnormalities in white matter have been linked to processing speed impairment in clinical populations (e.g., multiple sclerosis, closed head injury). Recent studies indicate the presence of significant reduction in cerebral white matter volume in some patients with chronic temporal lobe epilepsy (TLE). The objective of this study was to examine the relationship between white matter volume and processing speed and performance efficiency on the Sternberg Memory Scanning Test (SMST). The study groups included TLE subjects with white matter volume reduction (n=13), TLE subjects with normal white matter volume (n=14), and healthy controls (n=18). The groups did not differ in total cerebral gray matter volume. Compared with the controls, the reduced white matter volume TLE group exhibited a significantly steeper slope on the SMST. This was characterized by a disproportionate increase in reaction time with increased processing demands (set size), particularly for negative probe trials. In contrast, no significant differences on the SMST were evident between controls and the normal white matter volume TLE group. These findings suggest the presence of information processing speed and efficiency impairment in TLE and its relationship with white matter volume integrity.

Adolescent↗

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

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

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↗