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D S Geldmacher

Publications and source records attributed to D S Geldmacher.

17 recordsLinked to original sources
PubMed1998

Ectopic cell cycle proteins predict the sites of neuronal cell death in Alzheimer's disease brain.

Alzheimer's disease (AD) is a major dementing illness characterized by regional concentrations of senile plaques, neurofibrillary tangles, and extensive neuronal cell death. Although cell and synaptic loss is most directly linked to the severity of symptoms, the mechanisms leading to the neuronal death remain unclear. Based on evidence linking neuronal death during development to unexpected reappearance of cell cycle events, we investigated the brains of 12 neuropathologically verified cases of Alzheimer's disease and eight age-matched, disease-free controls for the presence of cell cycle proteins. Aberrant expression of cyclin D, cdk4, proliferating cell nuclear antigen, and cyclin B1 were identified in the hippocampus, subiculum, locus coeruleus, and dorsal raphe nuclei, but not inferotemporal cortex or cerebellum of AD cases. With only one exception, control subjects showed no significant expression of cell cycle markers in any of the six regions. We propose that disregulation of various components of the cell cycle is a significant contributor to regionally specific neuronal death in AD.

Aged↗
PubMed1998

Stimulus characteristics determine processing approach on random array letter-cancellation tasks.

Target-to-distractor ratio strongly influences performance on typical random array letter cancellation tasks, suggesting that a "controlled" processing approach is used. This study was designed to determine whether "automatic" processing could be also demonstrated in the random array cancellation paradigm by changing the perceptual characteristics of the stimuli. Thirty-two healthy subjects sequentially performed four random array cancellation tasks with 50 and 100 stimuli. The letters "I" or "O" were targets and "L" served as the distractor. Performance was measured by the number of correctly canceled targets divided by the time to completion, corrected for accuracy. There was a strong effect of the number of stimuli on forms using I targets (p < .00001), but not for O's (p = . 15) Performance scores were lower for I target forms than for O targets. These findings demonstrate that performance approximating "automatic" processing can also be elicited on clinically useful, office-based, or bedside tests such as random array cancellation.

Adult↗
PubMed1998

The effect of character and array type on visual spatial search quality following traumatic brain injury.

Disorders of visuomotor function are common following traumatic brain injury (TBI), but spatially directed visual attention has received little study in this population. 'Cancellation' testing is a common bedside method for assessing directed attention, which can provide information on how task properties influence visual scanning and search following severe TBI. Groups of 20 individuals after severe TBI and 21 healthy control subjects were matched for age and education. Participants performed finger tapping tests to assess motor speed as well as four cancellation tests employing letter and geometric figure stimuli in random and structured arrays. Control and TBI groups differed significantly on measures of accuracy, task completion time, and search quality. There was no significant effect of stimulus or array type on accuracy or time. Figure targets in a higher search quality, suggesting a right hemispheric dominance effect on these tasks. The findings support a deficit in visuomotor scanning performance in TBI beyond a purely motor effect. Interactions between stimulus and array types suggest that hemispheric cooperation is required for the optimal performance of these tasks, and that interhemispheric communication may be preferentially compromised by TBI.

Adolescent↗
PubMed1998

Clock drawing test in very mild Alzheimer's disease.

OBJECTIVES: The primary objective of this study was to determine the efficacy of the clock drawing test to predict the presence of very mild Alzheimer's disease (AD). A secondary objective was to identify elements of clock drawing that were most useful in differentiating cognitively intact older adults from those with mild Alzheimer's disease. DESIGN: Cohort based comparison of retrospective data. SETTING: Academic research center. PARTICIPANTS: Clock drawings from 41 outpatient cases of mild AD with Mini-Mental State Exam scores of 24 or higher and 39 age- and education-matched older adults were scored. MEASUREMENTS: Clock drawings were blindly and independently scored by two raters using the Clock Drawing Interpretation Scale and the scoring system reported by Rouleau et al. Predictive values for positive and negative tests were calculated using cut-off scores for total score and component subscores from each of these two systems. RESULTS: Two or more errors in the depiction of the clock hands on the Clock Drawing Interpretation Scale had a positive predictive value for AD of 100% and a negative predictive value of 51%. A score of 2 or less on the 4-point hand-placement component of the Rouleau et al. scoring system provided a positive predictive value for AD of 94% and was associated with a negative predictive value of 62%. CONCLUSION: An individual who commits two errors or more in drawing the clock hands deserves further investigation for a possible dementia. Normal hand placement on the clock drawing test does not exclude AD. However, when prevalence rates of dementia in community-dwelling older adults are considered, these results argue that normal clock hand placement indicates that dementia is unlikely.

Aged↗
PubMed1997

Effect of stimulus number, target-to-distractor ratio, and motor speed on visual spatial search quality following traumatic brain injury.

The object of this study was to investigate stimulus effects and motor limitations on visuospatial performance after traumatic brain injury (TBI). Previous findings have not fully explained the basis of attentional impairments after TBI. There has been little study of the spatial aspects of attention and information processing in this group. We studied 20 patients after severe TBI and 21 healthy controls. Four random-array letter cancellation tasks, varying in number of stimuli (50 and 100) and target-to-distractor ratio (1:4 and 1:9) were employed. Performance was calculated from the number and proportion of cancelled targets, as well as time to completion. TBI subjects were slower on finger tapping and achieved lower cancellation performance scores. Both TBI subjects and controls performed better on tasks with target-to-distractor (T/D) ratios of 1:4 than on those with 1:9. There was no effect of stimulus number. We conclude that there are both quantitative (speed) and qualitative contributors to impaired visuospatial ability following TBI. Motor impairments may slow the overall cancellation performance, but the differential effect of T/D ratio in the two populations suggests that TBI impairs quality of research. Accounting for both speed and accuracy suggests increased utility for the cancellation paradigm in clinical and research assessment of visuospatial attention.

Adolescent↗
PubMed1997

Treatment of functional decline in adults with Down syndrome using selective serotonin-reuptake inhibitor drugs.

Alzheimer's disease (AD) is a common cause of functional decline in Down syndrome (DS) adults. Acquired cognitive deficits may be difficult to evaluate in the context of baseline impairments. Behavioral symptoms are also common and may represent the effects of depression, AD, or both. Therefore, the objective of this study was to report a clinical case series of selected adults with DS and behavioral change who responded to treatment with selective serotonin-reuptake inhibitor (SSRI) medication. Six patients, aged 23 to 63 years, 5 women and 1 man, with the clinical diagnosis of DS presented for diagnosis and treatment of functional decline in adult life. Noncognitive symptoms were prominent and included aggression, social withdrawal, and compulsive behaviors. Memory dysfunction was reported in varying degrees. Treatment with SSRI antidepressants was instituted for depressive, apathetic, and compulsive behaviors. Treated patients showed improvement in behaviors as reported by caregivers, and on objective measures, such as workplace productivity. Noncognitive symptoms are a cardinal feature of functional decline in adults with DS and may represent either depression or AD. In some patients, the symptoms respond well to SSRI agents with concomitant improvement in daily function. Treatment trials with SSRIs may, therefore, be warranted in such cases.

Adult↗
PubMed1997

Differential diagnosis of Alzheimer's disease.

Accurate diagnosis of dementia is essential to provide appropriate treatment as well as patient and family counseling. It may be difficult to differentiate dementia from delirium. In addition, several features distinguish dementia from depression, but the two can coexist and the distinction may be uncertain. Dementias can be grouped into two categories: dementia that presents without prominent motor signs and dementia that presents with prominent motor signs. Dementias without prominent motor signs include Alzheimer's disease, frontotemporal dementia, and Creutzfeld-Jakob and other prion diseases. Dementias characterized at onset by prominent motor signs include dementias with Lewy bodies, idiopathic Parkinson's disease, progressive supranuclear palsy, cortico-basal ganglionic degeneration, hydrocephalus, Huntington's disease, and vascular dementia. Routine diagnostic steps include a careful history, mental status screening, laboratory and imaging studies, and neuropsychologic testing. Genetic testing is available, but its use is controversial and raises complex ethical questions.

Alzheimer Disease↗
PubMed1997

Enhancing recovery from ischemic stroke.

Despite the intense efforts devoted to preventing and aborting cerebral ischemia, some individuals will continue to have completed infarctions. Failure of prevention or intervention does not, however, preclude therapeutic approaches to enhance recovery. This article will review working definitions applicable to the care and rehabilitation of patients after ischemic stroke. Significant, preliminary research on how adrenergic systems may alter the recovery from cerebral damage is also reviewed. Beneficial effects of agents which promote adrenergic function, and the adverse effects of monoaminergic blockade in animals and humans are discussed. The potential role of synaptic mechanisms like long-term potentiation is reviewed in the context of motor recovery. These factors are likely to have important implications in the future acute care of patients with completed stroke.

Activities of Daily Living↗
PubMed1996

Effects of stimulus number and target-to-distractor ratio on the performance of random array letter cancellation tasks.

Cancellation tests are commonly used in the clinical assessment of visuospatial function, but there has been little study of task characteristics influencing performance. This study was designed to assess factors which affect cancellation performance. Sixteen healthy subjects sequentially performed four random-array letter cancellation tasks. The forms contained 50 and 100 stimuli and target:distractor (T/D) ratios of 1:4 and 1:9 with target letter "A" and randomly selected letter distractors. The primary performance measure was calculated as the number of correctly cancelled targets divided by the time to complete the task, corrected for accuracy. This measure revealed a strong effect of T/D ratio (p < .0001), with performance adversely affected by higher proportion of distractors. There was no effect of stimulus number. This suggests that T/D ratio should be considered in cancellation test design and interpretation.

Adult↗
PubMed1996

Hallucinations.

Explore the source record for details and available documents.

Aged↗
PubMed1994

Visual field influence on radial line bisection.

An attentional bias toward far peripersonal space has been proposed as the mechanism underlying inaccurate bisection of lines oriented radially in the sagittal plane. The position of stimuli in the visual scene has also been proposed as an important determinant of visual attention. This study was designed to evaluate the relative contributions of spatial and visual field factors in bisection of radial lines. The usual linkage of distant space and upper visual field was dissociated by assessing line bisection above eye level. Ten normal subjects bisected twelve 20-30-cm lines 35 cm above eye level and the identical stimuli 35 cm below the eyes. The previous findings of misbisection of radial lines distant to true center was replicated when stimuli were presented below eye level. Lines above eye level were misbisected significantly closer to the subjects. The findings suggest that visual field position influences the allocation of attention in the radial axis of space.

Adult↗
PubMed1994

Pharmacotherapy for Alzheimer's disease.

Pharmacotherapy that is effective for AD is a major goal of extensive research programs throughout the world. With the approval of tacrine in the United States, an agent is now available that has demonstrated improvement in cognition for some AD patients. Other similar symptomatic therapies are likely to become available in the near future. In the long term, prevention and cure will be based on understanding pathogenesis, such as the genetic defects that can lead to disease in some families.

Alzheimer Disease↗