Biomedical subjects

C M Cullum

Publications and source records attributed to C M Cullum.

At least 37 records · Page 2Linked to original sources

PubMed1998

The Hopkins Verbal Learning Test and CVLT: a preliminary comparison.

A preliminary examination of the relationship between two clinical measures of verbal memory was conducted among healthy older subjects. Correlations between selected scores from the Hopkins Verbal Learning Test (HVLT) and the California Verbal Learning Test (CVLT) revealed that the total number of words learned across trials for both tests were significantly related (r =.74, p <.001), while there was no association between error rates (i.e., perseverations and intrusions). Recognition hits alone were not related, but recognition discriminability indices (accounting for false-positive errors) on the two measures were significantly correlated (r =.46, p =.02). While the HVLT appears to adequately assess basic verbal learning capacity, its utility in assessing some of the more complex and qualitative aspects of verbal learning and memory function may be limited, and interpretations of HVLT performances based on the CVLT literature must be made with caution. A clinical case example is presented to illustrate some of the issues in comparing performance on the HVLT and CVLT.

Journal Article↗

PubMed1997

Altered amyloid protein processing in platelets of patients with Alzheimer disease.

BACKGROUND: beta-Amyloid peptide, the core component of neuritic plaques in brain areas in patients with Alzheimer disease (AD), is 1 cleavage product of the beta-amyloid precursor protein (APP) in neurons and platelets. Alternate cleavage products of intact 140- to 150-kd APPs in platelets include nonamyloidogenic 120- to 130-kd and 110-kd isoforms. The possible differential significance of these 2 isoforms, structurally similar to protease nexin II, is unknown. OBJECTIVE: To determine whether the ratio of the 120- to 130-kd APP isoform to the 110-kd APP isoform as processed in platelets correlates with the presence of AD and/or the apolipoprotein E4 (ApoE4) allele, which is a major risk factor for AD. SETTING: The Alzheimer Disease Center at The University of Texas Southwestern Medical Center at Dallas. METHODS: The APP isoforms were quantitated with the use of 2 different Western blot detection methods in platelets from 15 patients with AD and 19 control subjects in whom genotyping of apolipoprotein E was performed. RESULTS: The mean ratio of the 120- to 130-kd APP isoform to the 110-kd APP isoform in the patients with AD was significantly lower than that of the control subjects (5.98 vs 7.64; P = .03 [method 1] and 5.98 vs 7.92; P = .01 [method 2]) after adjusting for age and the increased incidence of ApoE4 in patients with AD. The lower APP ratios were also associated with increased age and with the presence of an ApoE4 allele. CONCLUSIONS: The APP processing in platelets of patients with AD is different from that of control subjects. This difference, largely caused by factors other than the ApoE4 genotype, may reflect chronic platelet activation in patients with AD. The use of these data to estimate "AD risk," by using the APP isoform ratio, indicates an odds ratio of 1.75, suggesting possible utility as an adjunct in the diagnosis of AD. Moreover, these findings may relate to analogous alterations in APP processing that may occur in brain areas affected by AD.

Aged↗

PubMed1997

Neuropsychological diagnosis and outcome in mild traumatic brain injury.

Despite its frequency, many, aspects of mild traumatic brain injury (MTBI) remain controversial. This likely reflects the inherent complexities of MTBI and its sequelae as well as various methodological issues in the literature. To further complicate matters, our understanding of what constitutes "necessary" and "sufficient" force to sustain a brain injury, remains limited, particularly in cases of nonimpact brain injury. Little debate exists regarding acute MTBI effects and postconcussional symptoms, although the issue of residual neuropsychological impairment remains hotly contested in many cases. Base rates of neuropsychological "impairment" must be considered in the context of individuals who present for evaluation following possible TBI or MTBI. In this article we highlight some of the critical issues in the assessment and diagnosis of MTBI, including the pitfalls of false-positive and false-negative diagnostic and interpretive errors.

Journal Article↗

PubMed1997

Education and cognitive function in Alzheimer's disease.

In normal aging, an association exists between level of education and verbal abilities. Clinical experience suggests that this relationship may also hold true in Alzheimer's disease (AD). In this study, we examined performance on selected verbal and nonverbal neuropsychological tests in a series of 51 patients with probable AD. Performance on two verbal measures-the National Adult Reading Test-Revised (NART-R) and the Vocabulary subtest from the Wechsler Adult Intelligence Scale-Revised (WAIS-R)-showed strong correlations with level of education. Scores on three nonverbal tests-WAIS-R Block Design, WAIS-R Digit Symbol, and Boston Diagnostic Aphasia Examination clock drawings-were unrelated to education. Consistent with our hypothesis, AD patients with higher premorbid education showed better performance on certain measures of verbal competence. These results indicate that, as in normal aging, education is associated with verbal abilities in AD.

Aged↗

PubMed1996

Neuropsychological dysfunction in parents of schizophrenics.

Neuropsychological measures designed to examine aspects of attention, learning efficiency, and memory were investigated in 14 schizophrenic probands, their 28 parents, and 18 normal individuals. Probands performed at levels significantly below normals on measures of attention and of learning efficiency and performed below their parents on a subset of the same measures. Eight families had one parent with a personal or ancestral pedigree history consistent with schizophrenia; the other parent's personal and ancestral history was negative for schizophrenia. In these families, the probands were significantly different from the negative-history parents, but not the positive-history parents on an aggregate index of attention. Schizophrenics were significantly different from both the positive- and negative-history parents on an aggregate index of learning efficiency. These results extend previous findings of specific neuropsychological dysfunction in attention and learning in schizophrenics to show that some of the deficits are present in a subgroup of their parents, those who are likely carriers of genes conveying risk for schizophrenia. The data suggest that a heritable component of the neuropsychological deficit is a primary dysfunction in attention, and that a secondary or additional deficit in learning may be evident in family members who actually express the disorder of schizophrenia.

Adult↗

PubMed1996

Genetic factors for the development of Alzheimer disease in the Cherokee Indian.

OBJECTIVE: To study the relationship between the genetic degree of Cherokee ancestry, the apolipoprotein E *E4 (APOE*E4) allele type, and the development of Alzheimer disease (AD) in individuals from the Cherokee Nation who reside in northeastern Oklahoma. SETTING: Alzheimer disease center satellite clinic and university departments of neurology, psychiatry, and academic computing. DESIGN: Standardized dementia evaluations based on criteria from the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association were performed on 26 patients aged 65 years or older to establish a diagnosis of AD. Twenty-six control subjects were recruited and similarly assessed. The APOE allele type determinations were obtained on all patients and control subjects. Appropriate statistical analyses were used to compare the genetic degree of Cherokee ancestry, the APOE allele type, and the development of AD. RESULTS: The data indicated that as the genetic degree of Cherokee Indian ancestry increased, the representation of AD decreased. The 9 patients with AD with a greater than 50% genetic degree of Cherokee ancestry constituted 35% of the group with AD. The 17 remaining patients with AD who were less than 50% Cherokee constituted 65% of the group with AD. In contrast, 17 (65%) of the control subjects were more than 50% Cherokee; only 9 (35%) were less than 50% Cherokee. These percentages of AD were not changed by the *E4 allele. This inverse relationship between the genetic degree of Cherokee ancestry and AD, independent of the APOE*E4 allele status, diminished with increasing age, suggesting an age-related protective effect of being Cherokee. For a decrease of 10% in Cherokee ancestry, the odds of developing AD are estimated to be 9.00 times greater at age 65 years but only 1.34 times greater at age 80 years. CONCLUSIONS: A greater genetic degree of Cherokee ancestry reduces the risk of developing AD and, thus, seems protective. This protective genetic factor is independent of APOE allele type and diminishes with age.

Aged↗

PubMed1996

Premorbid intelligence estimation and level of dementia in Alzheimer's disease.

Simple sight-word reading tasks have demonstrated utility in the estimation of premorbid intelligence, although the effects of progressive dementia on such tasks has not been thoroughly examined. The present investigation sought to examine estimated IQ scores from the National Adult Reading Test-Revised (NART-R; Blair & Spreen, 1989) in relation to a WAIS-R-based (Wechsler, 1981) estimate of IQ in a series of patients with probable Alzheimer's disease across varying levels of dementia. Results suggest that while NART-R scores do show a decrement with dementia severity, this decline is mild, in contrast to traditionally based IQ scores and other measures of cognitive function, which show more marked declines. Similarly, compared with other tasks, the NART-R showed the strongest correlation with education across the sample as a whole, while the other indices were more related to level of dementia. These findings support the use of measures such as the NART-R in estimating premorbid intellectual functioning in patients at various levels of dementia severity, including those with more advanced cognitive deterioration.

Aged↗

PubMed1996

Alzheimer's disease and its Lewy body variant: a clinical analysis of postmortem verified cases.

OBJECTIVE: The authors compared clinical findings of Alzheimer's disease and the so-called Lewy body variant of Alzheimer's disease. METHOD: Available data were analyzed on the clinical features of 58 patients with Alzheimer's disease and 24 patients with the Lewy body variant of Alzheimer's disease who underwent postmortem examination. RESULTS: The proportion of men was significantly larger in the Lewy body variant group than in the Alzheimer's disease group (66.7% versus 34.5%), and, concordantly, the Lewy body variant group was slightly taller. The prevalence of hallucinations and delusions was significantly higher in Lewy body variant subjects than the Alzheimer's disease subjects, but there were no significant differences between the two groups in educational attainment, family history of dementia, age at onset, duration of illness, cognitive impairment, overall severity of illness, or neuropsychological findings. Patients with the Lewy body variant of Alzheimer's disease tended to experience more frequent extrapyramidal side effects of neuroleptics than did the patients with Alzheimer's disease, but for patients in the two groups who were not exposed to neuroleptics, there was little difference in frequency of extrapyramidal side effects. CSF concentration of homovanillic acid (HVA) was significantly lower in the Lewy body variant patients, even when correction was made for height. CONCLUSIONS: The Lewy body variant of Alzheimer's disease may be suspected in elderly male dementia patients who otherwise meet criteria for Alzheimer's disease but who manifest significant psychiatric symptoms and neuroleptic-induced extrapy-ramidal side effects and have low levels of CSF HVA.

Aged↗

PubMed1995

Effects of bilingualism on verbal learning and memory in Hispanic adults.

The effect of bilingualism on qualitative aspects of verbal learning and memory was investigated. Equivalent list learning tests in English and Spanish were carefully constructed, and compared across two bilingual Hispanic groups of Mexican origin that differed in their level of English proficiency ("balanced" and "nonbalanced" bilinguals) and a group of monolingual English-speaking non-Hispanic subjects. Groups were matched for age, education, and gender composition. Nonbalanced bilinguals assessed in English utilized semantic clustering to the same extent as monolinguals, but learned fewer words overall, and demonstrated lower retention scores compared to monolinguals. Comparisons of groups assessed in their dominant languages, however, revealed no significant differences on any of the learning and memory indices examined. In addition to comparisons with standard clinical memory indices, assessment issues concerning bilingual individuals are addressed.

Adult↗

PubMed1995

Episodic memory function in advanced aging and early Alzheimer's disease.

Despite some well-documented differences, normal aging and Alzheimer's disease (AD) share a number of common neuropathological and neuropsychological features. Many of the reported differences are largely quantitative in nature and there is often overlap between the respective distributions of these populations. To assess the issue of overlap and distinguishing features in memory functions between these groups, and to minimize aging effects per se, samples of older individuals in good health (ages 75-95 yr) and younger patients in the early stages of AD (age < 75 yr) were selected to be similar in global cognitive functioning. Despite comparable language and visuospatial scores, these preliminary results suggest important qualitative differences in episodic memory functions between these conditions, even when "low-functioning" or "at-risk" controls are compared with early AD patients. These findings furthermore highlight some of the challenges in defining "normality" among the oldest segment of our population.

Aged↗

PubMed1994

Attention and vigilance functions in normal aging.

Clinical observation and considerable research have documented that a slowing of cognitive processing occurs in many healthy older persons. The neuropsychological characterization of this slowing, however, remains unclear, as does its neuroanatomic basis. In a preliminary attempt to help clarify this issue, we conducted two studies with healthy older individuals to evaluate whether declines in immediate and/or sustained attention appear with advancing age. In Study I, 166 subjects aged 50-69 and 70-90 were given several standard tests of immediate attention. No major differences in simple attentional function emerged. In Study II, 38 subjects in the same age ranges were administered tests of sustained attention. Significant differences between groups were seen on a digit cancellation task, despite similar performances on other measures requiring visual scanning and psychomotor speeded responses. The results of the two studies suggest that whereas simple attention tends to remain stable with aging, sustained attention appears to decline after the age of 70. This factor likely contributes to the general slowing of cognition often reported in the elderly, and may be associated with specific age-related neuroanatomic changes.

Journal Article↗

PubMed1994

Reduced platelet cytochrome c oxidase activity in Alzheimer's disease.

We evaluated a simplified method for preparation and analysis of platelet cytochrome c oxidase activity in Alzheimer's disease (AD) and control patients. Mean cytochrome c oxidase activity in controls (n = 17) was 0.233 sec-1/mg whereas mean cytochrome c oxidase activity in Alzheimer patients (n = 19) was 0.193 sec-1/mg, p = 0.033. Complex III (ubiquinol:cytochrome c oxidoreductase), complex II (succinic dehydrogenase), and citrate synthase were all assayed as internal controls and were not significantly different in controls and Alzheimer patients. There is a relatively specific loss of platelet cytochrome c oxidase activity in Alzheimer disease patients.

Aged↗

PubMed1994

Neurobehavioral and neurodiagnostic aspects of late-onset psychosis.

The onset of psychotic symptoms later in life requires careful multidisciplinary evaluation, yet may pose significant diagnostic difficulties given current classification schema. Here we describe a patient with new onset of schizophrenia-like symptoms at age 61. Cognitive screening and laboratory tests were within normal limits. However, detailed neuropsychological studies suggested mild to moderate, diffuse cerebral dysfunction, and MR revealed an arachnoid cyst around the right sylvian fissure. Three annual follow-up evaluations demonstrated no additional cognitive deterioration. Neuropsychological findings are discussed along with limitations of current psychiatric nosology and cognitive screening tasks in older patients with new-onset psychosis.

Journal Article↗

PubMed1993

Neuropsychological test performance and MEG-based brain lateralization: sex differences.

Magnetoencephalographic (MEG) auditory evoked fields (EF) were recorded from left and right hemispheres of 9 normal males and 12 normal females. Source location of the 100 ms latency component (M100) was localized to superior temporal lobes bilaterally using an inverse solution algorithm. All subjects also were administered the Wechsler block design and visual reproduction subtests, and the California Verbal Learning Test (CVLT). M100 source locations demonstrated significant sex differences in interhemispheric asymmetry. Males had source locations further anterior than females, with the differences most pronounced in the right hemisphere. Expected sex differences were found in neuropsychological test performance, with males performing better on block design ad visual reproduction, and females performing better on the CVLT. Across both sexes, block design scores correlated significantly with right hemisphere M100 location, with more anterior source locations associated with better performance. CVLT scores were negatively correlated with right hemisphere M100 source locations. These findings suggest MEG-based measures of interhemispheric asymmetry may be related to specific neuropsychological test performance measures.

Acoustic Stimulation↗

PubMed1993

Neurophysiological and neuropsychological evidence for attentional dysfunction in schizophrenia.

The behavior of the P50 wave of the auditory evoked potential in a paired stimulus or conditioning-testing paradigm has been used as a measure of sensory gating disturbance in schizophrenia. Schizophrenics fail to decrement the P50 response to the second stimulus of the pair, so that the ratio of the test to the conditioning amplitude is elevated over normal values. The aim of this study was to compare this neurophysiological measure to neuropsychological measures of attention and memory. As expected, schizophrenics performed worse than controls on most measures. The time to complete a digit cancellation test, a measure of sustained attention, was found to be particularly longer in schizophrenics than in control subjects. Furthermore, the increased time to complete this task correlated with the increased ratio of the amplitude of the test P50 response to the conditioning response in the schizophrenics. Thus, a neurophysiological defect in sensory gating may relate to a disorder in sustained attention in schizophrenia. Although the P50 wave may come from the hippocampus, neuropsychological measures of verbal learning and memory were not correlated with alterations in the P50 ratio.

Adult↗

PubMed1993

Three-word recall as a measure of memory.

Clinical examination of memory functions often includes the administration of simple free recall tasks, such as the recall of several words following a few minutes. Little is known, however, about the normative parameters or psychometric properties of such procedures, and such techniques have rarely been compared with more comprehensive, well-standardized memory indices. To address these issues, two three-word recall tasks were administered to a large group of carefully selected healthy subjects over the age of 50 years. The Mini-Mental State Examination (MMSE) was obtained as an index of global cognitive status, and the California Verbal Learning Test (CVLT) was used to exclude subjects with abnormal memory abilities. Significant but modest relationships were found between two three-word recall tasks and CVLT results. Substantial variability was seen on three-word recall, with a significant proportion of normal subjects recalling zero or one word. Results suggest using caution in interpreting simple recall performance as an index of memory, as great variability in results is seen among healthy (particularly older) individuals.

Aged↗

PubMed1993

The diagnostic utility of savings scores: differentiating Alzheimer's and Huntington's diseases with the logical memory and visual reproduction tests.

Recent research has demonstrated that patients with dementia of the Alzheimer type (DAT) evidence more rapid forgetting than do patients with Huntington's disease (HD). The present study focused on whether such group differences translated into measures with adequate sensitivity and specificity at different stages of these disorders. It was found that measures of forgetting (i.e., savings scores) based upon the Logical Memory and Visual Reproduction tests of the Wechsler Memory Scale--Revised had satisfactory to excellent sensitivity and specificity in differentiating DAT and HD patients from healthy control subjects. Savings scores also had good sensitivity and specificity in differentiating DAT from HD in the early stages of the diseases. However, unsatisfactory specificity may limit the utility of savings scores in differentiating among patients with moderate DAT and HD.

Aged↗

PubMed1993

Early detection of fronto-temporal degeneration by clinical evaluation.

Although Alzheimer's Disease (AD) is the most common degenerative dementia, other neuropathological processes are well known to cause dementia syndromes. Fronto-temporal degeneration (FTD) is one such entity, and often produces a clinical presentation distinct from that of AD. Some FTD cases are shown at autopsy to be classic Pick's Disease, but others defy precise classification at this point because they lack characteristic Pick bodies. We describe a case of putative FTD in a 54-year-old man with personality change and complete Klüver-Bucy syndrome. Neuropsychological evaluation disclosed evidence of extensive frontal system dysfunction, with lesser problems in memory, language, and visuospatial skills. Magnetic resonance imaging studies after 17 months of the illness were largely nonspecific, but a follow-up scan 16 months later revealed bifrontal and bitemporal atrophy with ventricular enlargement. Neuromorphometric analysis suggested an increase in cortical atrophy and ventricular dilation over time. This case emphasizes the value of careful clinical evaluation in unusual non-AD degenerative dementias and suggests that neuroimaging studies may be less sensitive in the early diagnosis of such cases.

Clinical Conference↗