Biomedical subjects

L A Flashman

Publications and source records attributed to L A Flashman.

28 records · Page 2Linked to original sources

PubMed1999

Neuropsychological correlates of methylphenidate treatment in adult ADHD with and without depression.

The purpose of this study was to characterize the neuropsychological profiles of adult patients with attention deficit hyperactivity disorder (ADHD) alone and ADHD with active comorbid depression, and to evaluate changes in the neuropsychological profile in these two groups following a trial of methylphenidate. Forty patients with ADHD were classified into two groups based on their affective status resulting in a group of 21 patients with ADHD alone and 19 patients with ADHD and active comorbid symptoms of depression (ADHD-D). All subjects received a comprehensive neuropsychological evaluation including measures of cognitive, motor and affective functioning before and after treatment. Fifteen normal controls were also assessed at a yoked time interval. At baseline, both patient groups showed impairment in verbal memory, motor and processing speed, visual scanning, and auditory and visual distractibility. Following treatment, both patient groups showed improvement across all neuropsychological measures while controls remained relatively stable over time. Improvement in neuropsychological test performance was not related to gender, affective status or referral source. Patients with active comorbid symptoms of depression show a similar neuropsychological profile and appear equally likely to benefit from methylphenidate intervention as patients with ADHD alone.

Journal Article↗

PubMed1998

Hippocampal volume reduction in schizophrenia as assessed by magnetic resonance imaging: a meta-analytic study.

BACKGROUND: Although many quantitative magnetic resonance imaging studies have found significant volume reductions in the hippocampi of patients with schizophrenia compared with those of normal control subjects, others have not. Therefore, the issue of hippocampal volume differences associated with schizophrenia remains in question. METHODS: Two meta-analyses were conducted to reduce the potential effects of sampling error and methodological differences in data acquisition and analysis. Eighteen studies with a total patient number of 522 and a total control number of 426 met the initial selection criteria. RESULTS: Meta-analysis 1 yielded mean effect sizes of 0.37 (P<.001) for the left hippocampus and 0.39 (P<.001) for the right, corresponding to a bilateral reduction of 4%. Meta-analysis 2 indicated that the inclusion of the amygdala in the region of interest significantly increased effect sizes across studies (effect size for the left hippocampus and amygdala, 0.67; for the right, 0.72), whereas variables such as illness duration, total slice width, magnet strength, the use of the intracranial volume as a covariate, measurement reliability, and study quality did not. No laterality differences were observed in these data. CONCLUSIONS: Schizophrenia is associated with a bilateral volumetric reduction of the hippocampus and probably of the amygdala as well. These findings reinforce the importance of the medial temporal region in schizophrenia and are consistent with frequently reported memory deficits in these patients. Future quantitative magnetic resonance imaging studies evaluating the hippocampal volume should measure the hippocampus and amygdala separately and compare the volumetric reduction in these structures to that observed in other gray matter areas.

Adult↗

PubMed1997

Lack of an association between delayed memory and hippocampal and temporal lobe size in patients with schizophrenia and healthy controls.

The purpose of the present study was to investigate putative neural substrates of long-term (delayed) memory in schizophrenia and young healthy controls. Ten "low" and 10 "high" memory patients were selected from a large sample of DSM-III-R diagnosed schizophrenia spectrum patients, based on composite verbal and nonverbal delayed recall memory scores. Ten "low" and 9 "high" memory individuals were also selected from a larger sample of young healthy controls. Magnetic resonance imaging scans were acquired on a 1.5-T GE Signa scanner using a SPGR sequence (repetition time = 24 msec, echo time = 5 msec). Hippocampal volumes were computed from manual tracings (intraclass correlation = .96), and temporal lobe and whole brain tissue volumes were obtained using a semiautomated technique. In both the patient sample and controls, there was no significant relationship between delayed memory ability and hippocampal, temporal lobe, or whole brain volume. The integration of results from this study, and from studies on normal aging and Alzheimer's disease, supports a model suggesting that hippocampal size may be an indicator of long-term memory ability, but only when hippocampal measures reflect aging and degenerative hippocampal atrophy. If the hippocampal measures reflect individual differences in hippocampal size prior to the onset of hippocampal atrophy, then hippocampal size does not appear to predict long-term memory ability.

Adult↗

PubMed1997

Neurocognitive and psychosocial correlates of ventroposterolateral pallidotomy surgery in Parkinson's disease.

The purpose of this study was to characterize the neuropsychological and psychosocial profile of patients with Parkinson's disease before and after they underwent unilateral left or right pallidotomy, to assess specific cognitive and personality changes caused by lesioning the globus pallidus, and to predict favorable surgical outcome based on these measures. Eighteen patients underwent comprehensive neuropsychological assessment before and after left-sided pallidotomy (10 patients) or right-sided pallidotomy (eight patients). The findings support the presence of frontosubcortical cognitive dysfunction in all patients at baseline and a specific pattern of cognitive impairment following surgery, with side of lesion being an important predictor of pattern and degree of decline. Specifically, patients who underwent left-sided pallidotomy experienced a mild decline on measures of verbal learning and memory, phonemic and semantic verbal fluency, and cognitive flexibility. Patients who underwent right-sided pallidotomy exhibited a similar decline in verbal learning and cognitive flexibility, as well as a decline in visuospatial construction abilities; however, this group also exhibited enhanced performance on a delayed facial memory measure. Lesioning the globus pallidus may interfere with larger cognitive circuits needed for processing executive information with disruption of the dominant hemisphere circuit, resulting in greater deficits in verbal information processing. The left-sided pallidotomy group also reported fewer symptoms of depression and anxiety following surgery. This enhanced mood functioning was not seen for the right-sided pallidotomy group. No relationships were noted between cognitive impairment or advanced age at baseline and surgicaloutcome. This study provides objective evidence for specific changes in neurocognitive and psychosocial functioning following left- and right-sided pallidotomy.

Journal Article↗

PubMed1996

Temporal lobe epilepsy and performance on the Wisconsin Card Sorting Test.

The replicability of previous evidence for differential performance between left and right temporal lobe epileptic patients on the Wisconsin Card Sorting Test (WCST) was evaluated in a new sample of candidates for focal resection. Many subjects obtained high scores on indices of perseveration, which are commonly thought to reflect frontal dysfunction, but there were no differences in performance between patients with language-dominant and nondominant temporal foci. The findings confirm existing evidence that performance decrements on the WCST can be associated with epileptic foci and focal lesions in nonfrontal brain lesions.

Adult↗

PubMed1996

Soft signs and neuropsychological performance in schizophrenia.

OBJECTIVE: Both neuropsychological impairment and neurological soft signs have been documented in at least a subset of patients with schizophrenia. The purpose of the present study was to examine the relationship between soft signs and neuropsychological performance in patients with schizophrenia in order to address the issue of whether soft signs are related to global or more selective cognitive impairment. METHOD: Patients with a DSM-III-R diagnosis of schizophrenia (N=176) were given a standardized neuropsychological battery and underwent a neurological examination. The study group was dichotomized on the basis of presence or absence of neurological soft signs. RESULTS: Patients with neurological soft signs (N=68) demonstrated significantly poorer performance on neuropsychological tasks that assessed timed motor speed and motor coordination (e.g., finger tapping, the Purdue Pegboard task, and part B of the Trail Making Test). These findings continued to be significant even after lifetime medication exposure, extrapyramidal symptoms, and abnormal involuntary movements were used as covariates. CONCLUSIONS: These findings support the notion that soft signs are a manifestation of a localizable behavioral deficit of the systems that are involved in motor speed, coordination, and sequencing and are not indicative of global cognitive impairment. The specific deficit in motor abilities is consistent with the types of neurological soft signs that are most frequently reported and suggests involvement of frontal/subcortical circuitry in schizophrenia.

Adolescent↗

PubMed1986

The effects of chronic desmethylimipramine on entorhinal cortical kindling in rats.

Chronic pretreatment of rats with desmethylimipramine (DMI) significantly slowed the rate of seizure generalization elicited by repeated electrical stimulation of the entorhinal cortex (kindling). An identical drug regimen administered to either fully kindled rats or rats partially kindled to early motor seizure stages failed to significantly alter kindling profiles in these animals. Under these latter conditions, in fact, there was a tendency for chronic DMI to exacerbate seizure activity. The effect of chronic DMI pretreatment to slow the development of kindled seizure generalization did not occur if a two-week delay was interposed between the end of drug treatment and the beginning of kindling trials. Results suggest that the retardation of entorhinal cortical kindling rate is dependent on DMI-induced CNS adaptations which recover within two weeks following treatment, and this effect is dependent on the presence of DMI-induced adaptations in a naive (unkindled) nervous system. Alterations of either the kindled state or the adaptational state produced by chronic drug eliminate the slowing of seizure generalization observed when both conditions are present.

Animals↗

PubMed1986

Meal patterns following changes in procurement cost for rats with fornix transection.

The purpose of the present study was to explore the effects of a varied procurement cost on the foraging behavior of rats with fornix transection. An operant analog of foraging requirements was used to examine the feeding patterns of the animals under free feeding, low procurement cost (FR5), and high procurement cost (FR80) situations, in an environment with minimal sensory distraction. It was found that animals with fornix transection did not differ from control rats in general consumption. Both groups were also able to adapt their feeding behavior to the varied procurement cost. As the procurement cost increased, the number of meals consumed decreased while the meal duration increased. The meal patterns themselves were different for the fornix transected animals and the control group. Animals with fornix transections ate more meals over the course of a day than did control animals; their meals were of a longer duration, and their intermeal intervals were shorter than those of control animals. During the course of a meal, the rats with fornix transections took a larger number of breaks, during which they drank, explored, or engaged in activities other than eating. These differences in the feeding patterns were seen across all procurement cost levels. The data support the possibility of hippocampal involvement in behavioral organization or sequencing.

Animals↗

PubMedDate not supplied

Clinical utility of the CERAD word list memory test.

The word list memory test from the Consortium to establish a registry for Alzheimer's disease (CERAD) neuropsychological battery (Morris et al. 1989) was administered to 230 psychiatric outpatients. Performance of a selected, age-matched psychiatric group and normal controls was compared using an ANCOVA design with education as a covariate. Results indicated that controls performed better than psychiatric patients on most learning and recall indices. The exception to this was the savings index that has been found to be sensitive to the effects of progressive dementias. The current data are compared and integrated with published CERAD data for Alzheimer's disease patients. The CERAD list memory test is recommended as a brief, efficient, and sensitive memory measure that can be used with a range of difficult patients.

Journal Article↗

PubMedDate not supplied

Automatic atlas-based volume estimation of human brain regions from MR images.

OBJECTIVE: MRI offers many opportunities for noninvasive in vivo measurement of structure-function relationships in the human brain. Although automated methods are now available for whole-brain measurements, an efficient and valid automatic method for volume estimation of subregions such as the frontal or temporal lobes is still needed. MATERIALS AND METHODS: We adapted the Talairach atlas to the study of brain subregions. We supplemented the atlas with additional boxes to include the cerebellum. We assigned all the boxes to 1 of 12 regions of interest (ROIs) (frontal, parietal, temporal, and occipital lobes, cerebellum, and subcortical regions on right and left sides of the brain). Using T1-weighted MR scans collected with an SPGR sequence (slice thickness = 1.5 mm), we manually traced these ROIs and produced volume estimates. We then transformed the scans into Talairach space and compared the volumes produced by the two methods ("traced" versus "automatic"). The traced measurements were considered to be the "gold standard" against which the automatic measurements were compared. RESULTS: The automatic method was found to produce measurements that were nearly identical to the traced method. We compared absolute measurements of volume produced by the two methods, as well as the sensitivity and specificity of the automatic method. We also compared the measurements of cerebral blood flow obtained through [15O]H2O PET studies in a sample of nine subjects. Absolute measurements of volume produced by the two methods were very similar, and the sensitivity and specificity of the automatic method were found to be high for all regions. The flow values were also found to be very similar by both methods. CONCLUSION: The automatic atlas-based method for measuring the volume of brain subregions produces results that are similar to manual techniques. The method is rapid, efficient, unbiased, and not subject to the problems of rater drift or potentially poor interrater reliability that plague manual methods. Consequently, this method may be very useful for the study of structure-function relationships in the human brain.

Anatomy, Artistic↗