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N Butters

Publications and source records attributed to N Butters.

At least 37 records · Page 2Linked to original sources
PubMed1995

The HNRC 500--neuropsychology of HIV infection at different disease stages. HIV Neurobehavioral Research Center.

The present study examined neuropsychological (NP) functioning and associated medical, neurological, brain magnetic resonance imaging (MRI), and psychiatric findings in 389 nondemented males infected with Human Immunodeficiency Virus-Type 1 (HIV-1), and in 111 uninfected controls. Using a comprehensive NP test battery, we found increased rates of impairment at each successive stage of HIV infection. HIV-related NP impairment was generally mild, especially in the medically asymptomatic stage of infection, and most often affected attention, speed of information processing, and learning efficiency; this pattern is consistent with earliest involvement of subcortical or frontostriatal brain systems. NP impairment could not be explained on the bases of mood disturbance, recreational drug or alcohol use, or constitutional symptoms; by contrast, impairment in HIV-infected subjects was related to central brain atrophy on MRI, as well as to evidence of cellular immune activation and neurological abnormalities linked to the central nervous system.

AIDS Dementia Complex↗
PubMed1995

Detection of dementia of the Alzheimer type in a population-based sample: neuropsychological test performance.

The ability to detect dementia of the Alzheimer type (DAT) in a community-dwelling sample of elderly individuals on the basis of neuropsychological test performance was examined. Three hundred sixty community-dwelling individuals were identified by neurological examination as having probable or possible Alzheimer's disease, being at risk for Alzheimer's disease, or having no cognitive impairment. A logistic model comprised of tests of verbal and nonverbal memory, mental flexibility, and confrontation naming correctly classified 82% of DAT subjects and 98% of normal elderly subjects. The logistic model classified 77% of subjects who were diagnosed as at risk for Alzheimer's disease as being cognitively normal. A cross-validation with a clinically based sample of subjects correctly classified 89% of DAT patients and 100% of normal control subjects. The results suggest that psychometric discrimination of dementia may be less accurate in community-dwelling populations than in clinically based samples.

Adult↗
PubMed1995

Semantic network abnormality predicts rate of cognitive decline in patients with probable Alzheimer's disease.

The present study examined the relationship between rate of cognitive decline in patients with Alzheimer's disease (AD) and the integrity of the network of associations that comprise their semantic knowledge. The integrity of the semantic network of 12 AD patients was determined by comparing their networks to a standard normal control network derived with Pathfinder analysis, a multidimensional graphic analysis technique. A simple linear regression analysis, comparing the degree of semantic network deterioration with rate of cognitive decline as measured by the difference between the Dementia Rating Scale (DRS) scores obtained at the time of the testing of semantic knowledge (Year 1) and one year later (Year 2), was highly significant (r2 = .84; p < .001). These results suggest that a sensitive measure of the structural deterioration of semantic knowledge may be useful for predicting the rate of progression of cognitive changes in patients with AD.

Aged↗
PubMed1995

Retrieval from semantic memory and its implications for Alzheimer's disease.

In 3 experiments, participants generated category exemplars (e.g., kinds of fruits) while a voice key and computer recorded each response latency relative to the onset of responding. In Experiment 1, mean response latency was faster when participants generated exemplars from smaller categories, suggesting that smaller mental search sets result in faster mean latencies. In Experiment 2, a concurrent secondary task increased mean response latency, suggesting that slowed mental processing results in slower mean latencies. In Experiment 3, the mean response latency of Alzheimer's participants was faster than that of elderly controls, which is consistent with the idea that the semantic memory impairments of Alzheimer's disease patients stem primarily from a reduction in available items (as in Experiment 1) rather than retrieval slowing (as in Experiment 2).

Aged↗
PubMed1995

Visual attention and perception in patients with Huntington's disease: comparisons with other subcortical and cortical dementias.

Shifts in attention were examined in patients with Huntington's disease (HD) using a divided attention paradigm that involved the presentation of global-local stimuli. The HD patients' pattern of performance was compared to the previously reported results of groups of patients with Alzheimer's disease (AD; Filoteo et al., 1992) or Parkinson's disease (PD; Filoteo et al., 1994). Across consecutive trials of the divided attention task, a visual target could appear at either the same global-local level or at a different level. When the target changed levels across consecutive trials, the AD patients demonstrated an impairment in disengaging attention from the level at which the last target appeared, whereas the PD patients were impaired in maintaining their attention at the previously attended level. In contrast to these patterns of performances, the HD patients did not demonstrate a significant impairment in shifting attention between hierarchical levels. Both the AD and the PD patients' abnormal shifting ability was significantly related to the number of errors they made in identifying target stimuli; however, the pattern of the relationship was qualitatively distinct. These results suggest that different attentional mechanisms may underlie AD and PD patients' visual-perceptual deficits. The HD patients' shifting ability was not related to the number of errors they made in identifying target stimuli, suggesting that a different mechanism may account for the visual-perceptual impairments exhibited by these patients.

Aged↗
PubMed1995

Impaired prepulse inhibition of acoustic and tactile startle response in patients with Huntington's disease.

The corpus striatum serves a critical function in inhibiting involuntary, intrusive movements. Striatal degeneration in Huntington's disease results in a loss of motor inhibition, manifested by abnormal involuntary choreiform movements. Sensorimotor inhibition, or "gating", can be measured in humans using the startle reflex: the startle reflex is normally inhibited when the startling stimulus is preceded 30-500 ms earlier by a weak prepulse. In the present study, prepulse inhibition (PPI) was measured in patients with Huntington's disease to quantify and characterise sensorimotor gating. Compared with age matched controls, patients with Huntington's disease exhibit less PPI. Startle gating deficits are evident in patients with Huntington's disease when startle is elicited by either acoustic or tactile stimuli. Even with stimuli that elicit maximal PPI in normal subjects, patients with Huntington's disease exhibit little or no PPI, and their pattern of startle gating does not show the normal modulatory effects usually elicited by changing the prepulse interval or intensity. Startle amplitude and habituation and latency facilitation are largely intact in these patients, although reflex latency is significantly slowed. In patients with Huntington's disease, startle reflex slowing correlates with cognitive impairment measured by the dementia rating scale, and with the performance disruptive effects of interference measured by the Stroop test. These findings document a profound disruption of sensorimotor gating in patients with Huntington's disease and are consistent with preclinical findings that identify the striatum and striatopallidal GABAergic efferent circuitry as critical substrates for sensorimotor gating of the startle reflex.

Acoustic Stimulation↗
PubMed1995

Episodic memory changes are associated with the APOE-epsilon 4 allele in nondemented older adults.

OBJECTIVE: To compare the memory performances of nondemented older adults with and without the epsilon 4 allele of the apolipoprotein E (APOE-epsilon 4). BACKGROUND: Few studies have examined the cognitive status of subjects at high risk for the development of dementia of the Alzheimer type (DAT). A newly reported risk factor for DAT allows for an examination of the cognitive performances of nondemented subjects who are at risk by virtue of being either heterozygous or homozygous for the APOE-epsilon 4 allele. METHODS: The California Verbal Learning Test (CVLT) was administered to 52 nondemented older adults. Subjects were divided into two groups on the basis of the presence (n = 17) or absence (n = 35) of one or two APOE-epsilon 4 alleles. RESULTS: APOE- epsilon 4 and non-epsilon 4 groups did not significantly differ in demographic, mental status, and functional characteristics. APOE-epsilon 4 subjects demonstrated significantly poorer mean performances than non-epsilon 4 subjects on nine CVLT variables. Seven group differences remained significant, and three approached significance (0.05 < p < 0.10), after the effects of age and gender were taken into account. Six of the 14 APOE-epsilon 4 subjects who completed annual follow-up evaluations developed either DAT or questionable DAT, whereas none of the 26 non-epsilon 4 subjects who received follow-up demonstrated any cognitive decline. CONCLUSIONS: Results suggest that episodic memory changes in older adults are associated with APOE-epsilon 4 allele; sensitive cognitive markers such as those of the CVLT may precede the subsequent development of DAT.

Aged↗
PubMed1995

Distinct cognitive profiles of cortical and subcortical dementia in advanced illness.

We administered the Mattis Dementia Rating Scale (DRS) to 120 patients to evaluate the effect of dementia severity on distinct cognitive profiles. Sixty patients with Huntington's disease (HD) and 60 patients with Alzheimer's disease (AD) were separated by dementia severity into three groups: mildly demented (DRS mean total = 129), moderately demented (DRS mean total = 117), and severely demented (DRS mean total = 102). At all levels of dementia severity, HD patients demonstrated greater impairment than AD patients on the Initiation/Perseveration subscale, whereas AD patients demonstrated greater impairment than HD patients on the Memory subscale. At moderate and severe levels of dementia, HD patients demonstrated an additional impairment in constructional praxis. These profile differences were independent of dementia severity and continued to differentiate between so-called cortical and subcortical dementias in later stages of dementia severity.

Adult↗
PubMed1995

Cognitive recovery with abstinence and its relationship to family history for alcoholism.

OBJECTIVE: The relationship between drinking relapse and family history for alcoholism to cognitive functioning was investigated in alcoholics who completed a 28-day inpatient treatment program. METHOD: The current study examined 144 primary alcoholics who completed a battery of cognitive tests on admission to treatment and at a 3-4 month follow-up visit. Participants were classified as either family history positive (FH+) (n = 86) or family history negative (FH-) (n = 58) based on information on alcohol dependence in first degree relatives. The subjects were further classified as drinkers (n = 56) or abstainers (n = 88) at follow-up, based upon information gathered about their drinking practices during the interval. RESULTS: There were no differences between the groups based on family history status at admission to treatment. Comparisons made at follow-up revealed that the abstainers' (both FH+ and FH-) performance improved. The FH+ drinkers' performance was worse than that of both the FH- drinkers and the FH+ abstainers at follow-up. The poor performance of the FH+ drinkers relative to the FH- drinkers was not attributable to differences in drinking consumption during the test-retest interval. CONCLUSIONS: These results suggest that alcoholics who maintain abstinence following treatment show improvement on cognitive testing at follow-up; both FH+ and FH- abstainers showed improvement, indicating that a positive family history of alcoholism does not impede recovery that occurs with abstinence. The most important finding, however, is that the FH+ drinkers show greater deterioration at follow-up compared to the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Clinical correlates of cortical and nucleus basalis pathology in Alzheimer dementia.

OBJECTIVE: We correlated severity of dementia in Alzheimer's disease with the degree of neuropathology in cortical and subcortical brain regions. METHODS: In 13 patients with Alzheimer's disease who underwent neuropsychological testing before death, we assessed neurofibrillary tangles, senile plaques, and neuronal and synaptic density in the midfrontal cortex and the nucleus basalis of Meynert. RESULTS: In the midfrontal cortex, synapse density was the strongest correlate of dementia severity, followed by neurofibrillary tangles. In the nucleus basalis, by contrast, neurofibrillary tangles were the strongest correlate, followed by synapse density. Stepwise regression analyses showed midfrontal synapse density to be the strongest predictor of tests emphasizing higher cortical functions, but neurofibrillary tangles in the nucleus basalis were the strongest predictor on memory-oriented tests. CONCLUSIONS: The specificity of pathology in cortical vs subcortical locations for predicting a particular quality of neuropsychological deficit probably reflects disruption of corticocortical connections vs derangement of the basal forebrain cholinergic system.

Aged↗
PubMed1994

Increased pressure for rapid eye movement sleep at time of hospital admission predicts relapse in nondepressed patients with primary alcoholism at 3-month follow-up.

OBJECTIVE: To determine whether polygraphic sleep recordings, obtained at the time of admission to an inpatient alcohol treatment program, predict abstinence and relapse 3 months following hospital discharge in nondepressed patients with primary alcoholism. DESIGN: Two independent, consecutive cohorts of patients (group 1, n = 28; group 2, n = 17) underwent all-night polygraphic sleep recordings and other clinical evaluations during the first and fourth weeks of a 1-month inpatient treatment program within a Veteran Affairs Medical Center. They were reevaluated 3 months following discharge to the community. None were treated with disulfiram or other medications during or after hospitalization. PATIENTS: All subjects were male veterans with primary alcoholism and without significant preexisting, secondary, or comorbid diagnoses such as major medical problems, depression, antisocial personality, or drug addiction. OUTCOME MEASURES: Relapse was defined as any alcohol consumption between discharge from the hospital and 3-month follow-up. RESULTS: Ten (36%) of 28 patients in group 1 were Relapsers at 3-month follow-up. Relapsers in group 1 showed significantly shorter Rapid Eye Movement (REM) latency, increased Rapid Eye Movement percent (REM%), and increased REM Density during their admission sleep studies compared with Abstainers. To replicate these observations, group 2 was then studied as a validation sample. Six (35%) of 17 patients relapsed. As in group 1, Relapsers had significantly shorter REM latency and increased REM% compared with Abstainers; REM Density was not significantly different in the Relapsers as compared with Abstainers in group 2. Using a principal components analysis based on these three REM sleep measures to determine "REM pressure," three separate discriminant function analyses (DFAs) were calculated: one for each group and one for all patients (n = 45) together. The DFA from group 1 correctly classified 22 (78.6%) of the 28 patients in group 1 and 13 (76.5%) of the 17 patients in group 2 as Relapsers or Abstainers. The DFA from group 2 correctly classified 13 (76.5%) of the 17 patients in group 2 and 23 (82.1%) of the 28 patients in group 1. The DFA formed from both groups together correctly classified 36 (80%) of the 45 patients. When the REM sleep measures at hospital admission and discharge were compared, no statistically significant effect of time was observed. Abstinence and relapse were not consistently related to other clinical measures at the time of hospital admission such as age, duration and severity of alcoholism, marital status, employment, hepatic enzyme levels, cognitive performance, or depression ratings. CONCLUSION: Short REM latency, increased REM%, and, possibly, increased REM Density at the time of admission to a 1-month inpatient alcohol treatment program predict relapse in nondepressed patients with primary alcoholism by 3 months following hospital discharge.

Alcohol Drinking↗
PubMed1994

Verbal memory performance of patients with human immunodeficiency virus infection: evidence of subcortical dysfunction. The HNRC Group.

In the present study, the California Verbal Learning Test (CVLT) was administered to symptomatic HIV+ (n = 31), asymptomatic HIV+ (n = 94), and HIV-normal control (HIV-NC) (n = 40) subjects to assess the prevalence and nature of their verbal memory deficits. Symptomatic HIV+ subjects were significantly impaired relative to HIV-control subjects on CVLT measures of acquisition and retention, and were significantly less likely than control subjects to use a semantic clustering strategy to support recall. The performance of the asymptomatic HIV+ subjects fell between those of the symptomatic HIV+ subjects and HIV-controls on almost every CVLT measure. A linear discriminant function analysis (DFA) was used to compare the performances of these three groups to Alzheimer's disease (AD). Huntington's disease (HD), and normal control (NC) subjects on three CVLT measures, including total recall over five learning trials, intrusion errors, and a derived score of delayed recognition discriminability minus the final learning trial. Significant differences were found between the number of symptomatic HIV+ subjects classified as HD (32%), AD (3%), and normal (65%), the number of asymptomatic HIV+ subjects classified as HD (16%), AD (1%), and normal (83%), and the number of HIV-NC subjects classified as HD (2%), AD (0%), and normal (98%). The profile of verbal memory deficits exhibited by the subgroup of impaired HIV+ subjects was similar to that of patients with HD, a prototypical subcortical dementia, and different from that of patients with AD, a prototypical cortical dementia. This finding is consistent with reports of the predominance of subcortical neuropathological changes associated with HIV infection.

AIDS Dementia Complex↗
PubMed1994

Volumetric magnetic resonance imaging quantification of longitudinal brain changes in abstinent alcoholics.

Magnetic resonance imaging (MRI) of the brain was performed on a group of 24 recently detoxified, male alcoholics approximately 1 month after their date of last drink. The imaging was repeated 3 months later, at which point 9 subjects had resumed drinking and 15 had maintained abstinence. Contrasts between these two drinking groups revealed that, despite comparable baseline values, the Abstainers exhibited volumetric white matter increases and cerebrospinal fluid reductions over the follow-up interval, whereas the Drinkers did not show significant change on either of these MRI indices. These results provide the first evidence suggestive of significant volumetric white matter increase with abstinence.

Adult↗
PubMed1994

Hippocampal connectivity and Alzheimer's dementia: effects of synapse loss and tangle frequency in a two-component model.

Our prior research on patients with Alzheimer's disease (AD) found a high correspondence between premortem dementia and accumulation of neurofibrillary tangles (NFTs) with concurrent loss of synapse density in several brain regions. In the present study, we examined these same clinicopathologic relationships in the context of seven subregions of the hippocampal formation using a sample of 16 AD patients who had been administered three well-known mental status tests antemortem. We found NFT counts to be most strongly correlated with degree of dementia when they were seen in CA1, the subiculum, and CA4; NFTs in these subregions appeared significantly clustered on factor analysis. Synapse loss was most strongly correlated with dementia when it occurred in the molecular layers of the dentate fasciculus and stratum lacunosum, CA2/3, and CA4; synapse loss in these subregions appeared significantly clustered on factor analysis. In general, these results were compatible with a two-component model of hippocampal connectivity and function in the context of AD. The first component consists of subregions preceding CA1 in a hypothesized input-processing sequence intrinsic to the hippocampus that summates neuronal excitation and that influences cognition primarily through synapse density. The second component consists of an "output module," mainly CA1 and the subiculum, that receives the processed signal, passes it on to extrahippocampal cortical and subcortical targets, and affects cognition primarily by NFT accumulation in output neurons. A "net pathology" score combining standardized z-scores for synapse density and NFTs was significantly correlated with all three mental status measures in all hippocampal subregions except the entorhinal cortex, and stepwise regressions on these data found net pathology in CA4 to be the most independent significant predictor of premortem dementia.

Aged↗
PubMed1994

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part V. A normative study of the neuropsychological battery.

The neuropsychological tests developed for the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) are currently used to measure cognitive impairments of Alzheimer's disease (AD) in clinical investigations of this disorder. This report presents the normative information for the CERAD battery, obtained in a large sample (n = 413) of control subjects (ages 50 to 89) who were enrolled in 23 university medical centers in the United States participating in the CERAD study from 1987 to 1992. We compared separately the performance of subjects with high (> or = 12) and low (< 12) years of formal education. For many of the individual cognitive measures in the highly educated group, we observed significant age and gender effects. Only the praxis measure showed a significant age effect in the low-education group. Delayed recall, when adjusted for amount of material acquired (savings), was relatively unaffected by age, gender, and level of education. Our findings suggest that the savings scores, in particular, may be useful in distinguishing between AD and normal aging.

Aged↗
PubMed1993

Nonverbal amnesia and asymmetric cerebral lesions following encephalitis.

Global amnesia after herpes simplex encephalitis has been typically associated with lesions of anterior and medial temporal lobe, inferior and medial frontal lobe, and insula. The neuropathologic correlates of this disease are usually considered to be bilateral and similar across cases. We describe a 27-year-old woman whose chronic amnesia and cerebral lesions after viral encephalitis indicate a different pattern. Two features distinguish her presentation: (1) markedly asymmetric lesions extensively involving the right temporal lobe but sparing almost all of the same structures on the left and (2) severe compromise of nonverbal learning and a nonverbal retrograde amnesia in contrast to disproportionately small impairments of verbal learning and retention. The findings suggest that encephalitis patients cannot be treated as a homogeneous group and that detailed analysis of variability in their anatomic lesions may be an important explanatory factor in neural accounts of these severe human amnesias.

Adolescent↗
PubMed1993

Recognition and naming of famous faces in Alzheimer's disease: a cognitive analysis.

A Famous Faces Test designed to assess face recognition, spontaneous naming, verbal identification of un-named faces, and cued naming using semantic and phonetic cues was administered to 22 patients with dementia of Alzheimer type (DAT) and 25 matched controls. The DAT patients were significantly impaired in all test conditions with evidence of a temporal gradient for recognition, identification and naming with phonemic cues, but not for spontaneous naming or naming with semantic cues. Analysis of the effects of disease severity showed that performance in all five conditions of the test declined with increasing disease severity, but this did not reach significance for recognition or for naming with phonemic cues. The DAT patients identified and named a significantly smaller proportion of the faces that they recognized than did the controls, and at no stage was identification significantly better than spontaneous naming. These findings indicate that the primary deficit was not one of name access, but an actual loss of stored knowledge about the person represented. In keeping with this observation, semantic cueing did not aid naming. These findings are discussed in the context of contemporary cognitive models of face processing.

Aged↗