Biomedical subjects

N Monson

Publications and source records attributed to N Monson.

At least 19 recordsLinked to original sources

PubMed2005

Characterizing the mechanisms of progression in multiple sclerosis: evidence and new hypotheses for future directions.

Major advancements have been achieved in our ability to diagnose multiple sclerosis (MS) and to commence treatment intervention with agents that can favorably affect the disease course. Although MS exacerbations and the emergence of disability constitute the more conspicuous aspects of the disease process, evidence has confirmed that most of the disease occurs on a constitutive and occult basis. Disease-modifying therapies appear to be modest in the magnitude of their treatment effects, particularly in the progressive stage of the disease. Therapeutic strategies currently used for MS primarily target the inflammatory cascade. Several potential mechanisms appear to be involved in the progression of MS. Characterizing these mechanisms will result in a better understanding of the various forms of the disorder and how to effectively treat its clinical manifestations. It is our objective within this 2-part series on progression in MS to offer both evidence-based observations and hypothesis-driven expert perspectives on what constitutes the cause of progression in MS. We have chosen areas of inquiry that appear to have been most productive in helping us to better conceptualize the landscape of what MS looks like pathologically, immunologically, neuroscientifically, radiographically, and genetically. We have attempted to advance hypotheses focused on a deeper understanding of what contributes to the progression of this illness and to illustrate new technical capabilities that are catalyzing novel research initiatives targeted at achieving a more complete understanding of progression in MS.

Disease Progression↗

PubMed1999

Eating disorders and psychiatric disorders in the first-degree relatives of obese probands with binge eating disorder and obese non-binge eating disorder controls.

OBJECTIVE: The purposes of the present study were to examine the possibility of a familial tendency for binge eating disorder (BED) among the obese, to clarify the relationship between BED and other eating disorders, and to test the relationship between BED and other psychiatric disorders. METHOD: We studied 32 female BED outpatients and 23 obese females without BED. A possible history of eating disorders was assessed using the Structured Clinical Interview for DSM-III-R-Eating Disorders section administered by telephone interview. Family history information for other psychiatric disorders was collected using the Family History Research Diagnostic Criteria RESULTS: The frequency of all eating disorders and the risk for other psychiatric disorders were not significantly different between the relatives of the two groups. These results were consistent across generation and gender. DISCUSSION: This study failed to show a familial tendency for BED, or any significant familial relationship between BED and other eating disorders, and did not support the hypothesis of coaggregation of other psychiatric disorders with BED.

Adult↗

PubMed1997

Two-dimensional cancellation neglect a review and suggested method of analysis.

Directional bias on cancellation has thus far not been standardized. While cancellation tasks are primarily used to assess lateral performance asymmetries, they may also reveal two-dimensional (i.e., combined lateral and radial) neglect patterns. We propose a method to evaluate and report cancellation neglect regardless of whether the neglect pattern is strictly unilateral or two-dimensional. Our method establishes the location of the geographic center of all neglected stimuli relative to the page center by averaging their Cartesian coordinates. This "neglect center" is reported in polar coordinates to indicate its distance and direction from the page center. We apply our method to published examples of two-dimensional neglect. We find that neglect centers from different cancellation performances may not be statistically distinct even though they may occupy different quadrants. In addition, the net direction of neglect found by the coordinate method may differ from that inferred from measuring differences in quadrant omission totals. The suitability of the coordinate vs. the quadrant method will depend on the mechanism hypothesized for visuospatial exploration under particular test conditions. Using both approaches may detect different attentional biases operating during the same task. The coordinate method is appropriate for conventional cancellation testing. By incorporating the precise locations of all neglected stimuli and determining the net neglect direction in two dimensions, the technique may stimulate more comprehensive explanations for directional bias.

Attention↗

PubMed1996

Problem solving by patients with multiple sclerosis: comparison of performance on the Wisconsin and California Card Sorting Tests.

Problem solving by patients with clinically definite multiple sclerosis (MS) was examined using the Wisconsin and California Card Sorting Tests (WCST and CCST). On the WCST, the MS patients achieved fewer categories and made more perseverative responses and errors than controls, confirming results of several previous studies. On the CCST, the MS patients generated and identified fewer concepts, but they performed normally when sorting was cued by the experimenter and they made no more perseverations than controls. Although findings from the WCST indicate that the problem solving deficits by MS patients closely resemble those exhibited by patients with various conditions that produce frontal lobe dysfunction, results from the CCST indicate that the problem solving difficulties exhibited by patients with MS are distinct and probably represent a primary deficit in concept formation.

Adult↗

PubMed1994

Picture and motor sequencing in multiple sclerosis.

Previous studies consistently report that patients with multiple sclerosis (MS) perform poorly on the Picture Arrangement subtest of the Wechsler Intelligence test. Although this finding implies that MS causes difficulties in cognitive sequencing, the Picture Arrangement test taps many cognitive abilities in addition to sequencing, and the reported deficits by MS patients could reflect difficulties in other skills such as information processing speed or visual acuity and scanning. To circumvent some of these interpretive problems, we used an untimed test of sequencing that required arranging relatively large drawings of familiar scenarios. The MS patients were impaired on this picture sequencing test, but they performed normally on the Luria three-step test of motor sequencing. Correlational analyses showed that picture and motor sequencing were highly correlated, and that performance on both sequencing tests was related to performance on a global mental status exam, the Wisconsin Card Sorting Test and Benton's Facial Recognition Test, but not to upper limb speed and dexterity. These findings demonstrate a relatively specific deficit in cognitive sequencing by MS patients, that can be partially dissociated from impairment in performing simple motor acts.

Adult↗

PubMed1993

Memory and frontal lobe dysfunction in schizophrenia and schizoaffective disorder.

Verbal memory and performance on a number of tests known to be sensitive to lesions that disrupt frontal lobe functioning were studied in patients with schizophrenia or schizoaffective illness. Both patient groups were severely and equally impaired on verbal and design fluency and on the Wisconsin Card Sorting Test, measures that are sensitive to dysfunction of frontal-striatal circuitry. Both patient groups exhibited impaired recall but nearly normal recognition memory, a pattern that is typically observed in frontal and subcortical diseases. Accelerated forgetting was evident on delayed recall tests; the magnitude of this impairment was greater for schizophrenic than for schizoaffective patients. These results suggest that frontal and/or subcortical dysfunction is common to schizophrenia and schizoaffective disorder. A subgroup including the majority of schizophrenic patients, however, exhibit a mild amnesia-like disorder which may result from pathological changes in the structure and function of the temporal lobes or the medial diencephalon.

Adult↗

PubMed1992

Decreased alpha bandwidth responsiveness to photic driving in Alzheimer disease.

The power spectra of the photically activated occipital EEGs of 9 mildly to moderately demented probable Alzheimer disease (AD) patients (according to NINCDS-ADRDA criteria), 9 normal age-matched control and 27 normal subjects of different ages were compared. In normal subjects, photic stimulation with rhythmic flashes ranging between 2 and 20 Hz elicited a characteristic response in each EEG bandwidth (delta, theta, alpha, beta1 and beta2). The magnitude of each bandwidth response was a function of the frequency of the photic stimulus. In AD patients the alpha bandwidth response curve was significantly smaller than that of age-matched controls (MANOVA main effect of group, P = 0.018); all the other bandwidth response curves were normal. Therefore, in AD there is a selective abnormality in the alpha bandwidth responsiveness to photic stimulation, probably due to AD pathology in the neuronal generator of the alpha rhythm.

Aged↗

PubMed1992

Does distraction reduce pain-produced distress among college students?

College students in four experiments placed their hands in ice water (the cold-pressor task) and reported their distress. They simultaneously engaged in different reaction-time (RT) tasks that varied in the amount of attention required for successful performance. In each experiment, which differed in numerous procedural details, RT, error-rate, and self-report measures all demonstrated that the distraction tasks differed in the degree of attention required. Greater distraction, however, failed to reduce physiological, self-report, or behavioral responses to the cold-pressor task. These data call into question the hypothesis that attention mediates the process whereby distraction tasks reduce pain-produced distress.

Adaptation, Psychological↗

PubMed1991

Metamemory in multiple sclerosis.

MS patients and age- and education-matched normal controls were administered several laboratory tests of metamemory and a questionnaire designed to measure subjects' capability to appraise their ability to remember events that might occur in everyday life. On laboratory tasks involving newly acquired information, MS patients with poor recognition memory abilities or poor performance on the Wisconsin Card Sorting Test (WCST) exhibited impairments on one test of metamemory; patients with deficits in both recognition and on the WCST showed more extensive impairments in metamemory. In contrast to their performance on tests involving newly acquired information, all groups of MS patients predicted their ability to recognize answers to general information questions that they could not recall as accurately as controls, and, like controls, they also searched their memories longer for answers to items that they believed they would recognize. In general, the results support the hypothesis that both trace-access and inferential mechanisms, which are thought to involve the prefrontal cortex, contribute to metamemory, but the nature of the memory task importantly influences the accuracy of metamemory, as well. Results from the questionnaire indicated that many MS patients with demonstrable memory deficits do not acknowledge their memory difficulties. Hence, patient self-reports about memory are likely to be unreliable sources of information for clinical purposes.

Adult↗

PubMed1990

Clinical and demographic predictors of cognitive performance in multiple sclerosis. Do diagnostic type, disease duration, and disability matter?

Patients with chronic progressive multiple sclerosis often perform more poorly on cognitive tasks than do patients with the relapsing-remitting form of this disease. Whether these differences reflect an independent influence of disease type on cognitive performance is uncertain. We used multiple regression techniques to determine how well performance on a number of tasks done poorly by groups of patients with multiple sclerosis could be predicted by disease type and its confounds: age, disease duration, and disability status as well as other demographic variables. Disease types were assigned longitudinally, based on serial neurological examinations at 6-month intervals over a minimum of 2 years. None of the demographic or clinical variables predicted cognitive performance with more than minimal accuracy. These findings fail to provide support for the assertion that disease type is an important independent determinant of cognitive impairment in multiple sclerosis.

Adult↗

PubMed1989

Cognitive disturbances in patients with relapsing remitting multiple sclerosis.

The performance of 42 patients with relapsing remitting (RR) multiple sclerosis was compared with that of 24 age-, education-, and gender-matched control subjects on a battery of neuropsychological tests known from previous studies to be sensitive to the impairments of patients with chronic progressive (CP) multiple sclerosis. Like CP patients, RR patients exhibited deficits on tests of information-processing speed, verbal fluency, and problem solving, and on recall measures of anterograde and remote memory. Although a few patients were mildly dysnomic, the RR patients were not generally impaired on visual confrontation naming and they did not exhibit perseverative responding on verbal fluency measures. The pattern of neuropsychological deficits exhibited by RR patients closely approximates the profile observed in other subcortical dementias and does not contain the features of cortical dementia evident in some CP patients. The impairment of RR patients on cognitive tests were less severe than those observed in CP patients in our previous studies. Differences in the age of patients in the CP and RR groups did not account for group differences in the severity of cognitive impairments, but differences in disease duration or severity of disability, as well as disease course, could explain why CP patients exhibit more serious cognitive disturbances than RR patients.

Adult↗

PubMed1989

Frontal lobe dysfunction and memory impairment in patients with chronic progressive multiple sclerosis.

Deficits in semantic encoding have been described in patients with frontal lobe disease who also show memory impairments. As a group, patients with multiple sclerosis (MS) exhibit memory impairment, fail to make effective use of semantic encoding to aid memory, and perform poorly on verbal fluency and concept formation tests which are sensitive to frontal lobe damage. In the present study the semantic encoding capacity of MS patients was measured using a modification of Wicken's release from proactive interference (PI) paradigm. Individual patients varied considerably in the severity of their impairments on verbal fluency, verbal recognition memory and on Wisconsin Card Sorting Task, but even patients who evidenced both memory impairment and signs of frontal lobe dysfunction showed normal release from PI after a categorical shift. Memory disturbances in MS are unlikely to result from an incapacity for semantic encoding, which seems preserved in MS, but may arise instead from deficits in processing information rapidly.

Adult↗

PubMed1988

Anterograde and retrograde amnesia in patients with chronic progressive multiple sclerosis.

The performance of 38 patients with chronic progressive multiple sclerosis was compared with that of 26 age- and education-matched controls on a battery of tests of information-processing speed, verbal fluency, naming, egocentric perception, and anterograde and remote memory. Although there were marked differences in the extent and severity of cognitive disturbance among individual patients, as a group they were impaired compared with controls on all measures. Deficits were most striking on the Symbol-Digit Modalities Test and the verbal fluency measures, tests that require rapid information processing. More than 75% of the patients scored below the tenth percentile for controls on the Symbol-Digit Modalities Test, while 61% scored below the tenth percentile on verbal fluency. Memory disturbances were also common. More than 45% of the patients scored below the tenth percentile. The proportion of impaired patients was quite similar for anterograde and remote memory tests and for recall and recognition procedures. The pattern of memory disturbance and slowed information processing resembled deficits generally observed in subcortical dementias, such as Huntington's disease, but in addition, the patients with multiple sclerosis showed naming difficulties that are usually associated with cortical dementias, such as Alzheimer's disease.

Adult↗

PubMedDate not supplied

Age vs. aging in the pathogenesis of senile dementia of the Alzheimer type: electrophysiological evidence.

Is senile dementia of the Alzheimer type (SDAT) the end result of aging of the brain (serial or aging-related model) or the result of some other mechanism that runs in parallel to normal aging (parallel or age-related model)? This question can be answered by comparing variables that measure biological aging (aging-dependent variables, ADVs) of normal individuals and of SDAT patients. If the serial model applies, the values of the ADVs of SDAT patients should be at the upper end of the normal ADV curves. In control individuals the power of the alpha band in the 2-Hz flash-stimulated EEG at the posterior head regions increased with age, while the power of the delta band in the resting EEG at the anterior head regions decreased. In SDAT patients the ADVs were significantly different from normal and opposite to the trend of normal aging, supporting the parallel model and suggesting that the pathogenesis of SDAT is different from normal aging.

Adult↗

PubMedDate not supplied

Cognition-related EEG abnormalities in nondemented Down syndrome subjects.

Down syndrome (DS) subjects develop Alzheimer disease (AD) histopathology before they develop dementia. We compared the resting and flash stimulated electroencephalogram (EEG) of nondemented adult DS and age-matched control subjects, in search of EEG abnormalities that might correlate with AD histopathology. DS subjects had increased absolute power in all the EEG bands, independent of cognition functions measured by the Mini Mental State Examination and Picture Absurdities Test scores. In the power spectrum of the resting EEG, we found a cognition-related increase in power at 4.5 and 8.8 Hz, indicative of alpha-slowing, as in AD patients. In the stimulated EEG, we found several cognition-related abnormalities, such as decreased responses to 12-Hz stimulation and decreased integral of beta- and gamma-band responses, indicative of decreased responsiveness to photic stimulation, as in AD patients. Therefore, nondemented DS and AD patients share several cognition related EEG abnormalities which are probably due to AD histopathology.

Adult↗

PubMedDate not supplied

Severity of dementia correlates with loss of broad-band visual cortical responses.

We have shown that the response to flash stimulation of the occipital electroencephalogram (EEG) in Alzheimer disease (AD) patients is smaller than in normal subjects. To ascertain whether this is a specific feature of AD or a nonspecific effect of dementia, we investigated in AD and multi-infarct dementia (MID) patients the relationship between cognitive function, measured as Mini-Mental State Examination score, and EEG power response, measured as the difference in spectral power between flash-stimulated EEG and resting EEG. Both variables were positively correlated and the regression equations of AD and MID patients were not significantly different, showing nonspecificity. The coupling between cognitive function and power response is discussed in relation to the dynamic binding hypothesis of cognition.

Aged↗

PubMedDate not supplied

Cognitive disturbances in Parkinson's disease.

To test the hypothesis that the cognitive impairments that accompany Parkinson's disease (PD) arise from frontal lobe dysfunction, patients with idiopathic PD and controls were tested on a neuropsychological battery that included measures of anterograde memory, visuospatial perception, and naming, as well as several tests that are known to be sensitive to lesions of the frontal lobes. PD patients of normal mental status as measured by the Mini-Mental State Examination performed normally on the naming, line orientation, and verbal recognition memory tests but exhibited deficits on verbal recall. On tests of frontal lobe function, these patients showed mild deficits on a category fluency task and on the Wisconsin Card Sorting Test. However, their errors on the latter were not typical of patients with frontal lesions, and they performed normally on a letter fluency task and exhibited normal release from proactive interference. Patients of lower than normal mental status performed poorly on nearly all of the cognitive tasks including confrontational naming, line orientation, and recognition memory, suggesting that their cerebral dysfunction extended beyond subcortical-frontal circuits. The present study supports the usefulness of the Mini-Mental State Examination for cognitive screening of PD patients, but does not support the hypothesis that the cognitive impairments in PD arise principally from disruption of frontal lobe functioning.

Aged↗

PubMedDate not supplied

Lexical processing in Parkinson's disease and multiple sclerosis.

Patients with Parkinson's disease (PD) or multiple sclerosis (MS) were categorized as normal in naming (NN) or impaired in naming (IN) based on their performance on the Boston Naming Test. All patients scored at least 23 on the Mini-Mental State Examination. Both PDIN and MSIN patient groups exhibited poor naming performance when target words were elicited with semantic, visual or rhyming cues. They also performed poorly on the vocabulary subtest of the Wechsler Adult Intelligence Scale-Revised and had difficulty repeating sentences. PDNN and MSNN patients showed more selective deficits. These findings add to a growing literature demonstrating that language in general, and naming in particular, can be compromised in subcortical diseases even when global mental status is only mildly affected. The clinical implications of these observations are, however, unclear.

Adult↗