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Biomedical subjects

Lars Nyberg

Publications and source records attributed to Lars Nyberg.

At least 37 records · Page 2Linked to original sources
PubMed2005

Memory-provoked rCBF-SPECT as a diagnostic tool in Alzheimer's disease?

PURPOSE: Alzheimer's disease (AD) is a primary degenerative disease that progressively affects all brain functions, with devastating consequences for the patient, the patient's family and society. Rest regional cerebral blood flow (rCBF) could have a strategic role in differentiating between AD patients and normal controls, but its use for this purpose has a low discriminatory capacity. The purpose of this study was to evaluate whether the diagnostic sensitivity of rCBF single-photon emission computed tomography (SPECT) could be increased by using an episodic memory task provocation, i.e. memory-provoked rCBF-SPECT (MP-SPECT). METHODS: Eighteen persons (73.2+/-4.8 years) with mild AD and 18 healthy elderly (69.4+/-3.9 years) were included in the study. The subjects were injected with (99m)Tc-hexamethylpropylene amine oxime (HMPAO) during memory provocation with faces and names, followed by an rCBF-SPECT study. The rCBF (99m)Tc-HMPAO SPECT images were analysed using statistical parametric mapping (SPM2). Peaks with a false discovery rate corrected value of 0.05 were considered significant. RESULTS: On MP-SPECT, the AD group showed a significant rCBF reduction in the left parietal cortex in comparison with healthy elderly. At rest, no significant group differences were seen. CONCLUSION: Memory provocation increased the sensitivity of rCBF-SPECT for the detection of AD-related blood flow changes in the brain at the group level. Further studies are needed to evaluate MP-SPECT as a diagnostic tool at the individual level. If a higher sensitivity for AD at the individual level is verified in future studies, a single MP-SPECT study might be sufficient in the clinical setting.

Adult↗
PubMed2005

Impaired cognitive performance in patients with chronic burnout syndrome.

Chronic burnout refers to a syndrome caused by chronic stress. Clinical observations indicate that chronic burnout is associated with impaired cognitive functioning. However, there have been no systematic studies of the cognitive performance in chronic burnout patients. We have evaluated general cognitive ability, memory, and attention in 67 female patients treated for chronic burnout. The patients and 15 healthy control subjects were tested with standardized tests of verbal and nonverbal cognitive ability (WAIS), verbal (Claeson-Dahl) and nonverbal (Rey complex figures) memory, and visual and auditory attention (IVA). Significant reductions in nonverbal memory and auditory and visual attention were found for the patient group. These results indicate that patients with chronic burnout have specific cognitive impairments, which should be emphasized in the evaluation of symptoms and treatment regimes in this disorder.

Adult↗
PubMed2005

Stability, growth, and decline in adult life span development of declarative memory: cross-sectional and longitudinal data from a population-based study.

Five-year changes in episodic and semantic memory were examined in a sample of 829 participants (35-80 years). A cohort-matched sample (N=967) was assessed to control for practice effects. For episodic memory, cross-sectional analyses indicated gradual age-related decrements, whereas the longitudinal data revealed no decrements before age 60, even when practice effects were adjusted for. Longitudinally, semantic memory showed minor increments until age 55, with smaller decrements in old age as compared with episodic memory. Cohort differences in educational attainment appear to account for the discrepancies between cross-sectional and longitudinal data. Collectively, the results show that age trajectories for episodic and semantic memory differ and underscore the need to control for cohort and retest effects in cross-sectional and longitudinal studies, respectively.

Adult↗
PubMed2005

Daily life among the oldest old with and without previous hip fractures.

The aim of this cross-sectional study was to describe the oldest old, with and without previous hip fracture with regard to their ability to perform personal and instrumental activities of daily living (ADL); home adaptations received; possession of assistive devices; perceived health and morale. A random sample drawn from the population of 85-year-olds, all 90-year-olds and all > or =95-year-olds (n =253) in Umeå, a city in northern Sweden, were examined. Data obtained from assessments and interviews carried out in the participants' homes, as well as data from medical charts, were analysed. Those with an earlier hip fracture (n = 58) had more difficulties in performing both personal and instrumental ADLs than those without (n = 195) but regarding individual home adaptations and the possession of assistive devices for personal care, no differences were detected between the groups. Self-perceived health and morale were equally good in both groups. The conclusion drawn is that lifelong consequences, in the form of reduced abilities to perform ADLs and wheelchair dependency are common among the oldest old after a hip fracture. Therefore, trials concerning the effects of more extensive and prolonged rehabilitation following hip fracture would be of great interest

Activities of Daily Living↗
PubMed2005

Neuropsychological functioning and MMPI-2 profiles in chronic neck pain: a comparison of whiplash and non-traumatic groups.

We measured the neuropsychological functioning in 42 patients with chronic neck pain, 21 with a whiplash trauma and 21 without previous trauma. Subjectively, the whiplash group was more forgetful and had more concentration difficulties compared with the non-traumatic group. The neuropsychological tests did not reveal any differences between the two groups and a reference group of healthy individuals. Thus, chronic neck pain did not seem to interfere with neuropsychological functioning. The personality traits assessed with MMPI-2 in our 42 patients with chronic neck pain differed significantly from the normals on several scales. We also found that the whiplash group had more divergent test results than the non-traumatic group on the MMPI-2 test. Thus, it seems that the health status in those with chronic neck pain is closely linked to separate personality traits. It is concluded that the subjective complaints and poor performance in patients with chronic neck pain may be associated to somatization and inadequate coping, especially in chronic whiplash patients.

Adult↗
PubMed2005

Any novelty in hippocampal formation and memory?

PURPOSE OF REVIEW: Novel events tend to attract attention and become more effectively encoded in memory than predictable events. The hippocampus and medial-temporal cortical regions, along with regions of the prefrontal cortex, have been associated with enhanced memory for novel events. This review provides an update on recent studies of hippocampal novelty responses in relation to memory. RECENT FINDINGS: Several different types of novelty have been studied. Stimulus novelty effects have been observed as reduced neural activity in the medial-temporal and prefrontal regions when the same stimulus is repeatedly presented. Contextual novelty effects, the detection of a stimulus or event in an unexpected context, is impaired in patients with hippocampal damage. Single-trial analyses of brain activity show that the hippocampus rapidly habituates to contextually novel situations. Associative novelty, the detection of new arrangements of familiar stimuli, has also been related to the medial-temporal regions. A division of labour among the medial-temporal regions has been proposed such that associative novelty selectively engages the hippocampus, whereas stimulus novelty is mediated by the perirhinal cortex. However, a simple account of when the hippocampus versus other medial-temporal cortical regions is recruited awaits further studies. Increased dopaminergic and cholinergic neurotransmission may account for enhanced memory encoding of novel events, and relate to structural neuronal changes. SUMMARY: Interindividual variability in the responsiveness of the hippocampal-novelty system may be genetically mediated, and personality factors can also play a role. A better understanding of such variability can have implications for interventions aimed at supporting memory and for the treatment of drug abuse.

Attention↗
PubMed2005

Treatment of chronic stress in employees: subjective, cognitive and neural correlates.

This study reports the effect of an affect-focused intervention program, the Affect School, on stress, psychological symptoms, cognitive functioning and neural activity. Fifty employees in social service and education, with high levels of chronic stress, were randomly divided into a treatment (N=27) and control (N=23) group. Complete sets of data were available in 20 participants in the treatment group and 17 in the control group. The Perceived Stress Questionnaire assessed stress and the Symptom Check List-90 psychological symptoms before and after treatment. Episodic-memory functioning under focused and divided attention conditions was also assessed. Prior and after the Affect School, seven participants in the treatment group were studied with functional magnetic resonance imaging (fMRI) during episodic memory processing. After the Affect School there was a reduction in stress and psychological symptoms for the treatment group but not in the control group. The controls showed a reduction in episodic memory functioning whereas the performance of the treatment group remained intact. The fMRI scanning indicated a qualitative change in the neural network subserving episodic memory. These preliminary results suggest that the Affect School is effective on individuals with high stress.

Adaptation, Psychological↗
PubMed2005

Delirium is associated with poor rehabilitation outcome in elderly patients treated for femoral neck fractures.

The aim of this study was to describe risk factors for delirium and the impact of delirium on the rehabilitation outcome for patients operated for femoral neck fractures. Sixty-one patients, aged 70 years or older, consecutively admitted to the Department of Orthopaedic Surgery at Umeå University Hospital, Sweden for femoral neck fractures were assessed and interviewed during hospitalization and at follow up 4 months after surgery. Delirium occurred in 38 (62%) patients and those who developed delirium were more often demented and/or depressed. Patients with delirium were longer hospitalized and they were more dependent in their activity of daily living (ADL) on discharge and after 4 months. They had poorer psychological well-being and more medical complications than the nondelirious. A large proportion of the patients who developed delirium did not regain their previous walking ability and could not return to their prefracture living accommodation. Delirium after hip fracture surgery is very common especially among patients with dementia or depression. This study shows that delirium has a serious impact on the rehabilitation outcome from both short- and long-term perspectives. Because delirium can be prevented and treated, it is important to improve the care of elderly patients with hip fractures.

Activities of Daily Living↗
PubMed2004

Common fronto-parietal activity in attention, memory, and consciousness: shared demands on integration?

Fronto-parietal activity has been frequently observed in fMRI and PET studies of attention, working memory, and episodic memory retrieval. Several recent fMRI studies have also reported fronto-parietal activity during conscious visual perception. A major goal of this review was to assess the degree of anatomical overlap among activation patterns associated with these four functions. A second goal was to shed light on the possible cognitive relationship of processes that relate to common brain activity across functions. For all reviewed functions we observed a consistent and overlapping pattern of brain activity. The overlap was most pronounced for the bilateral parietal cortex (BA 7 and BA 40; close to the intraparietal sulcus), and dorsolateral prefrontal cortex (right BA 9 and left BA 6). The common fronto-parietal activity will be discussed in terms of processes related to integration of distributed representations in the brain.

Attention↗
PubMed2004

Intact frontal memory effect in older age and dementia.

Older adults and demented patients show preserved functioning on certain tests of implicit memory. In this issue of Neuron, Lustig and Buckner demonstrate that both groups show comparable repetition-based effects on response time and prefrontal activity relative to younger adults.

Aging↗
PubMed2004

Effects of a fall prevention program including exercise on mobility and falls in frail older people living in residential care facilities.

BACKGROUND AND AIMS: Impaired mobility is one of the strongest predictors for falls in older people. We hypothesized that exercise as part of a fall prevention program would have positive effects, both short- and long-term, on gait, balance and strength in older people at high risk of falling and with varying levels of cognition, residing in residential care facilities. A secondary hypothesis was that these effects would be associated with a reduced risk of falling. METHODS: 187 out of all residents living in 9 facilities, > or =65 years of age were at high risk of falling. The facilities were cluster-randomized to fall intervention or usual care. The intervention program comprised: education, environment, individually designed exercise, drug review, post-fall assessments, aids, and hip protectors. Data were adjusted for baseline performance and clustering. RESULTS: At 11 weeks, positive intervention effects were found on independent ambulation (FAC, p=0.026), maximum gait speed (p=0.002), and step height (> or =10 cm, p<0.001), but not significantly on the Berg Balance Scale. At 9 months (long-term outcome), 3 intervention and 15 control residents had lost the ability to walk (p=0.001). Independent ambulation and maximum gait speed were maintained in the intervention group but deteriorated in the control group (p=0.001). Residents with both higher and lower cognition benefited in most outcome measures. No association was found between improved mobility and reduced risk of falling. CONCLUSIONS: Exercise, as part of a fall prevention program, appears to preserve the ability to walk, maintain gait speed, ambulate independently, and improve step height. Benefits were found in residents with both lower and higher cognitive impairment, but were not found to be associated with a reduced risk of falling.

Accidental Falls↗
PubMed2004

Visual consciousness: dissociating the neural correlates of perceptual transitions from sustained perception with fMRI.

To investigate the possible dichotomy between the neurophysiological bases of perceptual transitions versus sustaining a particular percept over time, an fMRI study was conducted with subjects viewing fragmented pictures. Unlike most other perceptually unstable stimuli, fragmented pictures give rise to only one perceptual transition and a continuous period of sustained perception. Earlier research is inconclusive on the subject of which anatomical regions should be attributed to what temporal aspect of perception, and the aim of the present study was to shed more light on the subject. In this study occipitotemporal and fronto-parietal regions were found to be activated for both aspects. However, regions in the medial-temporal lobe were activated specifically for transitions, whereas medial and dorsolateral prefrontal regions were activated specifically for sustained perception. These results provide further support for the theory that the initial creation of perceptual awareness and upholding perceptual awareness over time are separate processes involving different brain regions.

Adult↗
PubMed2004

Task-independent and task-specific age effects on brain activity during working memory, visual attention and episodic retrieval.

It is controversial whether the effects of aging on various cognitive functions have the same common cause or several different causes. To investigate this issue, we scanned younger and older adults with functional magnetic resonance imaging (fMRI) while performing three different tasks: working memory, visual attention and episodic retrieval. There were three main results. First, in all three tasks, older adults showed weaker occipital activity and stronger prefrontal and parietal activity than younger adults. The occipital reduction is consistent with the view that sensory processing decline is a common cause in cognitive aging, and the prefrontal increase may reflect functional compensation. Secondly, older adults showed more bilateral patterns of prefrontal activity than younger adults during working memory and visual attention tasks. These findings are consistent with the Hemispheric Asymmetry Reduction in Older Adults (HAROLD) model. Finally, compared to younger adults, older adults showed weaker hippocampal formation activity in all three tasks but stronger parahippocampal activity in the episodic retrieval task. The former finding suggests that age-related hippocampal deficits may have a global effect in cognition, and the latter is consistent with an age-related increase in familiarity-based recognition. Taken together, the results indicate that both common and specific factors play an important role in cognitive aging.

Adult↗
PubMed2004

The extent of stability and change in episodic and semantic memory in old age: demographic predictors of level and change.

Structural stability and change in semantic and episodic memory performance as well as interindividual differences in 5-year changes in these constructs are examined within a sample of older adults (age rangeT1 = 60-80; n = 361). Interindividual differences in change were limited but significant. Stability coefficients were higher for semantic memory (.95) than for episodic memory (.87). Changes in episodic and semantic memory performance were strongly associated (r =.68). Across time, variances and covariances increased, and a tendency toward dedifferentiation in terms of increasing correlations was found. Chronological age was related to both level and change, but gender and education were only related to level of memory performance. Collectively, these results depict relatively high degrees of structural stability and stability of interindividual differences in declarative memory in old age.

Age Factors↗
PubMed2004

Selective sex differences in declarative memory.

Sex invariance of a six-factor, higher order model of declarative memory (two second-order factors: episodic and semantic memory; and four first-order factors: recall, recognition, fluency, and knowledge) was established for 1,796 participants (35-85 years). Metric invariance of first- and second-order factor loadings across sex was demonstrated. At the second-order level, a female advantage was observed for both episodic and semantic memory. At the first-order level, sex differences in episodic memory were apparent for both recall and recognition, whereas the differences in semantic memory were driven by a female superiority in fluency. Additional tests of sex differences in three age groups (35-50, 55-65, and 70-85 years of age) indicated that the female superiority in declarative memory diminished with advancing age. The factor-specific sex differences are discussed in relation to sex differences in hippocampal function.

Adult↗
PubMed2004

Why the elderly fall in residential care facilities, and suggested remedies.

OBJECTIVE: To study precipitating factors for falls among older people living in residential care facilities. DESIGN: Prospective cohort study. SETTING: Five residential care facilities. PARTICIPANTS: 140 women and 59 men, mean age +/- SD 82.4 +/- 6.8 (range, 65-97). MEASUREMENTS: After baseline assessments, falls in the population were tracked for 1 year. A physician, a nurse, and a physiotherapist investigated each event, and reached a consensus concerning the most probable precipitating factors for the fall. RESULTS: Previous falls and treatment with antidepressants were found to be the most important predisposing factors for falls. Probable precipitating factors could be determined in 331 (68.7%) of the 482 registered falls. Acute disease or symptoms of disease were judged to be precipitating, alone or in combination in 186 (38.6%) of all falls; delirium was a factor in 48 falls (10.0%), and infection, most often urinary tract infection, was a factor in 38 falls (7.9%). Benzodiazepines or neuroleptics were involved in the majority of the 37 falls (7.7%) precipitated by drugs. External factors, such as material defects and obstacles, precipitated 38 (7.9%) of the falls. Other conditions both related to the individual and the environment, such as misinterpretation (eg, overestimation of capacity or forgetfulness), misuse of a roller walker, or mistakes made by the staff were precipitating factors in 83 (17.2%) of falls. CONCLUSION: Among older people in residential care facilities, acute diseases and side effects of drugs are important precipitating factors for falls. Falls should therefore be regarded as a possible symptom of disease or a drug side effect until proven otherwise. Timely correction of precipitating and predisposing factors will help prevent further falls.

Accidental Falls↗
PubMed2003

The memory-enhancing effects of Ginseng and Ginkgo biloba in healthy volunteers.

RATIONALE: The use of herbal remedies, such as Ginkgo biloba and Ginseng, for improving cognitive performance has become increasingly popular during recent years. Several previous studies have indicated that administration of Ginkgo biloba and Ginseng may improve aspects of learning and memory in healthy volunteers. These results, however, are generally not supported by well-controlled clinical studies. Also, positive results have often been reported from studies investigating effects related to short-term, chronic administration of the extract. Nonetheless, both Ginkgo biloba and Ginseng are marketed as having the capacity to enhance cognitive functions, such as memory and learning, in the long term. OBJECTIVE: This study aimed at investigating whether the use of Ginkgo biloba and Ginseng for a long period of time has positive effects on performance on learning and memory. METHODS: Community-dwelling volunteers ( n=3500) from The Betula prospective cohort study: memory, health, and aging were included in the study. RESULTS: It was found that the use of neither Ginkgo biloba ( n=40) nor Ginseng ( n=86) was associated with enhanced memory performance in any of the eight memory tests examined, relative to control groups either using or not using nutritional supplements. CONCLUSIONS: These findings indicate that use of Ginkgo biloba or Ginseng does not provide any quantifiable beneficial effects on memory performance in the long-term in healthy adult volunteers.

Adult↗