Biomedical subjects

Ivar Reinvang

Publications and source records attributed to Ivar Reinvang.

17 recordsLinked to original sources

PubMed2006

Accelerated age-related cortical thinning in healthy carriers of apolipoprotein E epsilon 4.

Effects of APOE genotype on age-related slopes of cortical thinning was estimated by measuring the thickness of the cerebral cortex on a point-by-point basis across the cortical mantle in 96 healthy non-demented volunteers aged 48-75 years. Fifty nine were APOE epsilon 4- (no epsilon 4 allele) and 37 were epsilon 4+ (1 or 2 epsilon 4 alleles). The genotype groups had similar age, sex and IQ. Two T(1)-weighted MP-RAGE sequences were averaged for each participant to yield images with high signal-to-noise ratio, and quantified using semi-automated analysis tools. epsilon 4 carriers had thicker cortex than non-carriers in several frontal and temporal areas in both hemispheres, but showed a steeper age-related decline in adjacent areas. Upon comparison of the epsilon 4-specific age-related thinning with previously published patterns of thinning in normal aging and Alzheimer's disease (AD), we conclude that APOE epsilon 4 may function to accelerate thinning in areas found to decline in aging (medial prefrontal and pericentral cortex), but also to initiate thinning in areas associated with AD and amyloid-beta aggregation (occipitotemporal and basal temporal cortex).

Aged↗

PubMed2006

Mismatch negativity elicited by tones and speech sounds: changed topographical distribution in aphasia.

This study used the event-related brain potential mismatch negativity (MMN) to investigate preconscious discrimination of harmonically rich tones (differing in duration) and consonant-vowel syllables (differing in the initial consonant) in aphasia. Eighteen Norwegian aphasic patients, examined on average 3 months after brain injury, were compared to 11 healthy controls. The main finding was a difference in topographic distribution of the MMN: the aphasia group showed a less lateralized and centralized topographic pattern especially to CV syllables, which is consistent with a reduced temporal lobe processing contribution and an increased right hemisphere activation. No correlations between MMN amplitude and aphasia test results were found.

Acoustic Stimulation↗

PubMed2006

The functional and structural significance of the frontal shift in the old/new ERP effect.

There is a lack of studies mapping electrophysiological event-related potentials (ERPs) to structural neuroanatomical characteristics. The aim of the present study was to integrate electrophysiological memory-related activity with cortical and hippocampal volume, as well as psychometric memory performance, in a life-span sample. More specifically, we wanted to investigate the functional significance of the often-observed frontal shift of ERP amplitude with increasing age and whether neuroanatomical characteristics can explain this shift. Sixty six healthy participants (20-78 years) went through a neuropsychological examination, MRI scans, and a visual recognition ERP task with verbal stimuli. The results showed that ERPs elicited in the recognition memory task (the old/new effect) correlated significantly with cortical volume, but not with hippocampal volume. Large cortex predicted more differentiated ERP activity and not just larger amplitude in general, implying more distinct and efficient retrieval. Furthermore, ERP amplitude, cortical volume, and hippocampal volume all predicted scores on a composite memory scale. All these relationship were dependent upon the common influence of age. Finally, the participants with the most anterior distribution of activity showed the poorest recognition memory performance. Neither cortical nor hippocampal volume were related to this frontal shift. It is concluded that the distribution of activity along the anterior-posterior axis in a memory paradigm may have functional but not neuroanatomical volumetric correlates. The functional correlates need not be restricted to the older age groups.

Adult↗

PubMed2006

Regional cortical thickness matters in recall after months more than minutes.

The aim of this study was to determine the role of regional cortical thickness in recall of verbal material over an extended time period. MRI scans of healthy adults of varying ages were obtained. Two scans were averaged per person to achieve high spatial resolution, and a semi-automated method for continuous measurement of thickness across the entire cortical mantle was employed. Verbal memory tests assessing recall after 5 min, 30 min, and a mean interval of 83 days were administered. A general linear model (GLM) of the effects of thickness at each vertex on the different memory indices was computed, controlling for gender, age, IQ, and intracranial volume. These analyses were repeated with hippocampal volume as an additional variable to be controlled for, to assess to which extent effects of cortical thickness were independent of hippocampal size. Minute effects of cortical thickness were observed with regard to shorter time intervals (5 and 30 min). However, even when controlling for the effects of hippocampal volume, higher recall across months was associated with thicker cortex of distinct areas including parts of the gyrus rectus, the middle frontal gyrus, the parieto-occipital sulcus and the lingual gyrus of both hemispheres. In addition, hemisphere-specific associations were found in parts of the right temporal and parietal lobe as well as parts of the left precuneus. This supports a unique and critical role of the thickness of distinct cortical areas in recall after months, more than after minutes.

Adult↗

PubMed2006

Influence of major antiepileptic drugs on attention, reaction time, and speed of information processing: results from a randomized, double-blind, placebo-controlled withdrawal study of seizure-free epilepsy patients receiving monotherapy.

PURPOSE: All major antiepileptic drugs (AEDs) have been reported to be associated with cognitive side effects. Uncertainty exists regarding the degree of cognitive effects, primarily because many studies do not adhere to basic standards of methodology and design. The aim of this study was to assess the effect of discontinuation of AEDs in patients receiving monotherapy on measures of attention, reaction time, and speed of information processing. METHODS: The 150 subjects who had been seizure free>2 years on drug monotherapy went through a randomized, double-blind, placebo-controlled study. Each patient was included for 12 months or until seizure relapse. Cognitive function was assessed with the California Computerized Assessment Package at baseline and 7 months after discontinuation. RESULTS: The major finding in this study is that discontinuation of major AEDs significantly improved performance on tests that require complex cognitive processing under time pressure. The difference in speed of cognitive processing between the two groups on these tasks was between 24 to 43 ms. Simple tasks of attention and reaction time revealed no significant differences between the discontinuation group and the nondiscontinuation group. Most of the subjects in the study were medicated with carbamazepine (CBZ) and valproate (VPA). The outcome of discontinuation of CBZ was similar to the outcome for the total study population, whereas withdrawal of VPA revealed only a nonsignificant tendency in the same direction. CONCLUSIONS: The results suggest that seizure-free epilepsy patients receiving monotherapy can obtain improvement in cognitive function if they discontinue AED treatment.

Adolescent↗

PubMed2006

Predictors of neuropsychological impairment in seizure-free epilepsy patients.

Persons with epilepsy are at increased risk of cognitive deficits as a result of various factors like etiology, structural brain lesions, seizure frequency, seizure type, age at onset of epilepsy, hereditary factors, psychosocial factors, and possible adverse effects of antiepileptic drugs (AEDs). Despite the fact that the majority of epilepsy patients are seizure-free, previous studies on the relationship between epilepsy-related variables and cognitive function have mainly been conducted on patients with persisting seizures. In this study 158 adults with epilepsy on AED monotherapy and without epileptic seizures for at least 2 years were investigated with a neuropsychological test battery in addition to a neurological examination, MRI and EEG. The major findings were that the group had education and employment status similar to the population mean and neuropsychological function in the normal range. In the patient group without idiopathic generalized epilepsy known cerebral etiology was found to be a highly significant predictor of neuropsychological deficit. For patients with idiopathic generalized epilepsy, early seizure debut at < or =18 years was a powerful predictor of neuropsychological impairment.

Adult↗

PubMed2006

Interactive effects of APOE and CHRNA4 on attention and white matter volume in healthy middle-aged and older adults.

In the present study, we investigated age-related changes in interactions between efficiency of neuronal repair mechanisms and efficiency of cholinergic neurotransmission in the context of attentional orienting. In addition, we explored white matter volume changes as possible neuronal underpinnings. A sample of 230 healthy middle-aged (53-64 years) and older (65-75 years) adults was genotyped for polymorphisms of APOE and CHRNA4, a nicotinic receptor subunit gene. Participants were administered a visuospatial attention task involving letter discrimination with location cues of varying validity. Genotype effects on white matter volume were also investigated in a subset of participants who received MRI scans. APOE interacted with CHRNA4, such that APOE-epsilon4 carriers who were also CHRNA4 TT homozygotes showed disproportionately slowed reaction time (RT) following invalid location cues. The interaction was stronger in the middle-aged participants than in the older participants. There was also a trend for individuals with combined APOE-epsilon4/CHRNA4 TT genotypes to show both lower white matter volume and slower overall RT on the attention task The interaction of a neurotransmission gene (CHRNA4) and a susceptibility gene (APOE) suggests that the efficiency of neuronal repair mechanisms may modulate the cholinergic system to influence attentional function.

Aged↗

PubMed2005

Selective increase of cortical thickness in high-performing elderly--structural indices of optimal cognitive aging.

The aim of this study was to identify cortical areas important for optimal cognitive aging. 74 participants (20-88 years) went through neuropsychological tests and two MR sessions. The sample was split into two age groups. In each, every participant was classified as "high" or "average" on fluid ability tests and on neuropsychological tests related to executive function. The groups were compared with regard to thickness on a point-by-point basis across the entire cortical mantle. The old high fluid performers had thicker cortex than the average performers in large areas of cortex, while there was minimal difference between the groups of high vs. average executive function. Furthermore, the old group with high fluid function had thicker cortex than the young participants in the posterior cingulate and adjacent areas. Further analyses showed that the latter was a result of a complex aging pattern, differing between the two performance groups, with decades of cortical thickening and subsequent thinning.

Adult↗

PubMed2005

Age-dependent changes in distribution of P3a/P3b amplitude and thickness of the cerebral cortex.

With increasing age, the electrophysiological event-related potentials P3a/P3b tend to get a more frontal maximum. The cognitive significance of this so-called frontal shift is not known, but hypotheses have focused on changes in the integrity of the frontal lobes. The aim of the present study was to test how the thickness of the cerebral cortex is related to the frontal shift. Well screened elderly participants went through a visual three-stimuli oddball-task, a battery of neuropsychological tests and magnetic resonance imaging scans. It was found that participants with frontocentral maxima had a thicker cerebral cortex in distinct areas than participants with parietal maxima, both for P3a and for P3b, while the parietal P3b participants had a thicker cortex in the anterior cingulate. This is the first study to demonstrate that age-dependent changes in the scalp distribution of electrophysiological activity are related to differences in thickness of the cerebral cortex.

Aged↗

PubMed2005

Cognitive ERPs are related to ApoE allelic variation in mildly cognitively impaired patients.

Identification of biological or cognitive changes in brain function, associated with allelic variation in Apolipoprotein E, is important for unravelling the mechanism behind the increased risk for Alzheimer's disease associated with the varepsilon4 allele. Cognitive event-related potentials (ERPs) show high degrees of heritability and are sensitive to subtle cognitive deficits. They may, therefore, be good candidates for assessing allelic effects. Non-demented patients age 50-76 undergoing investigation for memory problems performed ERP paradigms for testing automatic (MMN) and cognitive (N1, N2, P3) attention functions. The results indicated attenuation in the amplitude of the N1 and N2 ERP components depending on the dose of the varepsilon4 allele. Findings are consistent with studies showing reduced fronto-temporal metabolic activity in ApoE4 carriers.

Aged↗

PubMed2005

Effects of age on volumes of cortex, white matter and subcortical structures.

The effect of age was investigated in and compared across 16 automatically segmented brain measures: cortical gray matter, cerebral white matter, hippocampus, amygdala, thalamus, the accumbens area, caudate, putamen, pallidum, brainstem, cerebellar cortex, cerebellar white matter, the lateral ventricle, the inferior lateral ventricle, and the 3rd and 4th ventricle. Significant age effects were found for all volumes except pallidum and the 4th ventricle. Heterogeneous age responses were seen in that age relationships for cortex, amygdala, thalamus, the accumbens area, and caudate were linear, while cerebral white matter, hippocampus, brainstem, cerebellar white, and gray matter, as well as volume of the lateral, inferior lateral, and 3rd ventricles showed curvilinear relationships with age. In general, the findings point to global and large effects of age across brain volumes.

Adult↗

PubMed2005

Cortical volume and speed-of-processing are complementary in prediction of performance intelligence.

The rationale for the present study was to investigate the relationship between cortical volume, the latency of the ERP component P3a (as a measure of speed-of-processing), and performance intelligence (not adjusted for age differences). Seventy-one participants aged 20-88 years underwent a visual 3-stimuli oddball ERP task, an MRI-scan, and intelligence testing. P3a latency and cortical volume shared 9% variance (p<.05) and both were significantly related to performance intelligence (R2=.26 and .40, respectively). The amount of explained variance increased significantly (to R2=.51) when both measures were used as simultaneous predictors. When a path diagram was constructed including age as an exogenous variable, P3a latency and cortical volume both significantly predicted performance intelligence, but were no longer related to one another. The main conclusion from the study is that speed and size are complementary in prediction of performance intelligence, and the theoretical implications are discussed.

Adult↗

PubMed2005

Age does not increase rate of forgetting over weeks--neuroanatomical volumes and visual memory across the adult life-span.

The aim of the study was to investigate whether age affects visual memory retention across extended time intervals. In addition, we wanted to study how memory capabilities across different time intervals are related to the volume of different neuroanatomical structures (right hippocampus, right cortex, right white matter). One test of recognition (CVMT) and one test of recall (Rey-Osterrieth Complex Figure Test) were administered, giving measures of immediate recognition/recall, 20-30 min recognition/recall, and recognition/recall at a mean of 75 days. Volumetric measures of right hemisphere hippocampus, cortex, and white matter were obtained through an automated labelling procedure of MRI recordings. Results did not demonstrate a steeper rate of forgetting for older participants when the retention intervals were increased, indicating that older people have spared ability to retain information in the long-term store. Differences in neuroanatomical volumes could explain up to 36% of the variance in memory performance, but were not significantly related to rates of forgetting. Cortical volume and hippocampal volume were in some cases independent as predictors of memory function. Generally, cortical volume was a better predictor of recognition memory than hippocampal volume, while the 2 structures did not differ in their predictive power of recall abilities. While neuroanatomical volumetric differences can explain some of the differences in memory functioning between younger and older persons, the hippocampus does not seem to be unique in this respect.

Adult↗

PubMed2005

Attention to affective pictures in closed head injury: event-related brain potentials and cardiac responses.

We examined whether closed head injury patients show altered patterns of selective attention to stimulus categories that naturally evoke differential responses in healthy people. Self-reported rating and electrophysiological (event-related potentials [ERPs], heart rate [HR]) responses to affective pictures were studied in patients with mild head injury (n = 20; CT/MRI negative), in patients with predominantly frontal brain lesions (n = 12; CT/MRI confirmed), and in healthy controls (n = 20). Affective valence similarly modulated HR and ERP responses in all groups, but group differences occurred that were independent of picture valence. The attenuation of P3-slow wave amplitudes in the mild head injury group indicates a reduction in the engagement of attentional resources to the task. In contrast, the general enhancement of ERP amplitudes at occipital sites in the group with primarily frontal brain injury may reflect disinhibition of input at sensory receptive areas, possibly due to a deficit in top-down modulation performed by anterior control systems.

Adolescent↗

PubMed2005

Age-differences in verbal recognition memory revealed by ERP.

Seventy-four participants (aged 20-82 years) went through a continuous performance recognition memory task with multiple repetitions of words and non-words while ERPs were recorded from the scalp. The old/new ERP effect (the difference in activation to stimuli correctly recognized as old and stimuli correctly recognized as new) for words but not non-words declined with increasing age in a linear pattern, but the relationship between the old/new effect and age varied throughout the ERP time window. Differences in topography between age groups were manifested in a frontal shift in activation for older age groups. Further, the data point to differences in semantic versus non-semantic processing across the adult life span, and it is concluded that specific cognitive memory processes are differentially involved at different ages.

Adult↗

PubMed2002

Hemispheric asymmetry in visual discrimination and memory: ERP evidence for the spatial frequency hypothesis.

Event related potentials (ERPs) were recorded during delayed discrimination of simple spatial frequency gratings in the high and low frequency bands. Analyses of the waveforms N170, P220, N310, P400, and slow wave (SW) indicated significant and regionally specific interaction of spatial frequency and hemisphere for N170 amplitude. This interaction was independent of memory conditions, and appeared to be in the opposite direction of what is predicted by the spatial frequency model of hemispheric asymmetry. Additional interactions between spatial frequency and hemisphere were observed for N310 in the encoding process (reference stimulus) and for SW in the retrieval process (test stimulus). The general hypothesis of an interaction of spatial frequency and hemisphere in visual cognition is supported, but the findings indicate caution in interpreting an increase in physiological measures as an indication of more efficient brain processing. Moreover, several stages of information processing may contribute to the asymmetry observed in behavioral studies, and hemispheric balance may change dynamically during the time course of processing.

Adult↗

PubMed2002

Assessment of P3a and P3b after moderate to severe brain injury.

The purpose of the study was to examine the P3a and P3b components of the event-related brain potential (ERP) in patients sustaining moderate to severe brain injury. Electrophysiological and behavioral responses were recorded in brain injured (N = 18) and healthy control (N = 21) participants performance of an auditory 3-stimulus distractor paradigm. Auditory stimuli consisted of a series of repetitive standard tones (75 ms), occasionally interrupted by equiprobable target (25 ms) and distractor sounds (white noise). Tone duration discrimination accuracy was similar in patients and controls, but patients had prolonged reaction times to targets. The reaction time delay was paralleled by a prolongation of P3b latency to targets in the patient group relative to controls. The stimulus and task dependent modulation of ERP responses in the brain injury group was similar to that of controls in terms of the spatial distribution of ERPs over the scalp. However, the brain injury group had attenuated P3a and P3b amplitudes to distractor and target stimuli, respectively. The electrophysiological data suggest a deficit in the allocation of attentional resources to the processing of deviant stimuli in the brain injury group.

Acoustic Stimulation↗