Harry Klonoff

Marijuana and Driving in Real-Life Situations

It is evident that the smoking of marijuana by human subjects does have a detrimental effect on their driving skills and performance in a restricted driving area, and that this effect is even greater under normal conditions of driving on city streets. The effect of marijuana on driving is not uniform for all subjects, however, but is in fact bidirectional; whether or not a significant decline occurs in driving ability is dependent both on the subjects capacity to compensate and on the dose of marijuana. For those subjects who improved their performance, the explanation may lie in overcompensation and possibly the sedative effect of the drug. Whereas the street portion of this study approximated normal driving conditions, it should be emphasized that the context of the driving experience een on city streets was experimental. the design of this study maximal safeguards in terms of a dual control vehicle and a driver observr; in addition, the subjects were proffessionally screened and, with rare exception, they were emotionally stable. Given the experimental setting and set, the safeguards, and the nature of the study sample, idiosyncratic behaviour that might occure under normal driving condition would be less likely to occur in a study such as this. Other identified factors might lead to more stringent conclussions regarding the effects of marijuana on driving.The first is night driving, which may be more stressful. But an even more important unanswered question is the cumulative effect of alcohol and marijuana on driving (64 percent of the study sample reported alcohol in combination with marihjuana before driving). Third, the doses of marijuana used in this study were within the range of social marijuana usage(1); more heroic doses might be taken before driving. Fourth, the effect of marijuana on reactions and decision during high speed is still another unknown. What are the recommendations that emarge from this study? Driving under the influence of marijuana should be avoided as much as should driving under the influence of alcohol. More investigation is urgently required—and high priority should be given to studies that approximate normal conditions of driving and in which alcohol and marijuana are administered to the same subjects.

Regional cerebral glucose metabolism in turner syndrome

Regional cerebral glucose metabolism was examined in females with Turner syndrome, a sex chromosome abnormality. Previous studies have found a visual/spatial cognitive anomaly in these women but, to date, no abnormalities in brain structure or function have been associated with the condition. In the present study, decreases in regional metabolism were found in the occipital and parietal cortex. The involvement of the occipital cortex, although consistent with the observed cognitive anomalies, has not been suggested previously as an area dysfunction. Because the occipital cortex is a primary sensory cortex, the reduction of glucose metabolism in the parietal cortex may reflect a lack of innervation from the occipital cortex. Besides insight into the functional specialization of the brain, these findings are also consistent with previous reports on animals regarding the effects of estrogen in brain maturation.

Neuropsychological performance in patients with mild multiple sclerosis

Although changes in cognitive function in patients with multiple sclerosis (MS) have been reported, these changes have been traditionally associated with the later stages of the disease. In the current study, a comprehensive neuropsychological battery was administered to MS patients (N= 86) in whom the disease progression was relatively mild and in remission and a demographically well-matched control group (N=46). Besides the expected differences in tests of motor function, the two groups also differed on a number of cognitive tests with no motor demands. The two cognitive functions that appear impaired were learning and memory. Given that similar deficits have been found in MS patients with more severe symptoms, it is argued that changes in cognitive function can occur in the mild stages of the disease.

The neuropsychological, psychiatric, and physical effects of prolonged and severe stress: 30 years later.

This study investigates the long term or residual effects resulting from severe and extended exposure to stress. The samples were prisoners of war who were interned in Japan (high stress group) or Europe (low stress group) during the Second World War. They were examined in the following three areas: neuropsychological, psychiatric, and physical/neurological. Significant differences were found in all three spheres between the two groups. Second, to examine further the effect of length of internment on these variables, the low stress group was divided into long term and short term internment duration groups, and then the three groups were compared. Significant differences were found among these three groups. These results are discussed in relation to a traditional model of explanation.

Ventricular size, cognitive function and depression in patients with multiple sclerosis

The purpose of this study was to explore further the hypothesis that changes in cognitive function may occur in the mild stages of multiple sclerosis (MS) by determining whether ventricular enlargement was related to cognitive function. Ten measures of ventricular size were made in a sample of 123 MS patients with mild disability and 60 well-matched healthy controls. In addition, sixteen tests of cognitive function and the Beck Depression Inventory were administered. For the MS group, there were significant correlations between the ventricular measures and cognitive performance but not for the normal controls. Scores on the Beck Depression Inventory were not correlated with either cognitive performance or ventricular enlargement. These findings suggest that for the MS group cognitive impairment was related to the disease process but not to the level of depression.

Factor Analysis of a Neuropsychological Battery for Children Aged 9 to 15

A neuropsychological battery comprised of 29 Halstead-Reitan variables, 2 Benton variables, 1 Reitan-Kløve variable, 16 Kløve variables, and the 12 WISC variables was given to 200 normal children, ages 9 to 15. Results of a principal component factor analysis indicated that at least 19 different dimensions were being measured. The dimensions of neuropsychological functioning were: Directional Sequencing of Visual Stimuli, Verbal Fluency, Static Motor Steadiness, Directed Motor Steadiness, Tactile Discrimination Speed, Coordinated Motor Speed, Undirected Motor Speed, Manipulative Dexterity, Patterned Critical Discrimination, Form Reproduction Accuracy, Crossed-modality Consistency, Set for Provisional Solutions, Cue Resultant Shifting of Attention, Tactile Retention, Alternation Between Conceptual Realms, Directed Motor Speed, Analytic-synthetic Visual-motor Ability, Form Reproduction Speed and Auditory Recognition. Regression weights and composite score formulae for estimating Ss scores on these 19 dimensions were presented. Dimensions corresponded to the verbal-performance division of the WISC. 14 factors were found to be relatively independent of psychometric measures of intelligence; 3 factors were interdependent with WISC performance variables; 1 factor was interdependent with a WISC verbal variable; 1 factor derived from WISC verbal variables. The derived factors were related to other factor analytic studies.

Models of cognitive deficit and statistical hypotheses: Multiple sclerosis, an example

The purpose of the current study was to describe four models of cognitive deficit and to outline the statistical hypotheses underlying each model. The four models of cognitive deficit were (a) specific deficit; (b) subgroup deficit; (c) a syndrome dissociation model; and (d) a global function dissociation model. Neuropsychological data are analyzed to examine each of these four models in a sample of mild Multiple Sclerosis (MS) patients. The results suggest that for these subjects and tests, the specific deficit model best fits the data. The results are reviewed initially in the context of MS. There follows a consideration of statistical caveats and finally, general applications of the proposed procedures.

Empirically derived groups in the assessment of recovery from aphasia.

Abstract This paper examines the pretreatment intercorrelation matrix of the subtests of the Porch Index of Communication Ability to derive factors reflecting components of language impairment. In addition to a general factor reflecting overall language dysfunction, five specific factors reflecting verbal competency (fluency), graphic-verbal expression, gestural-verbal expression, gestural-nonverbal comprehension, and graphic-geometric comprehension were found which accounted for 90.6% of the total variance. A cluster analysis of the five pretreatment factor scores yielded six groups which accounted for 79% of the variance for these factors. These groups were differentiated primarily in terms of impairment and showed a high rate of accuracy prediction for group membership (97.5%). These groups were extremely stable, as shown by the 75% accurate prediction rate derived from the post-treatment factor scores. The effectiveness of this model in generating homogeneous and highly discriminable groups based on objective measures of the patients language functions indicates that classification of patients into empirical groups should be a major concern of any research design. Implications for assessing effectiveness of therapeutic intervention and the design of test battery were also discussed.

Pathological association and dissociation of functional systems in multiple sclerosis and Huntington's disease

This study examined pathological associations and dissociations of functional cognitive systems in patients with multiple sclerosis and Huntingtons disease. Using the subtests of the WAIS-R, two motor tests, and the word fluency test, the interest correlations showed distinct patterns. In comparison to normals, the two clinical groups exhibited a greater degree of association among the tests. Subsequently, word fluency performance was predicted from these tests. For the normals, the overall predictive power was quite low (7%). For the MS group, the predictive power rose to 28%. For the HD group, the predictive power was 50%. These results suggest that pathological association of functional systems may be a marker of brain dysfunction and that the affected systems may be delineated by these methods.

Head Injuries in Children: A Model for Predicting Course of Recovery and Prognosis

Given the scope of the health problems deriving from head injuries of children, there is a paucity of comprehensive studies and, in particular, insufficient information regarding psychological sequelae. The more relevant published studies during the past decade have included Brink, Garrett, Hale, Woo-Sam, and Nickel (1970), Black, Blumer, Wellner, and Walker (1971), Klonoff (1971), Klonoff and Low (1974), Klonoff and Paris (1974), Mandle-berg and Brooks (1975), Fuld and Fisher (1977), Tsushima and Towne (1977), Levin and Eisenberg (1979), Rutter, Chadwick, Shaffer, and Brown (1980), Chadwick, Rutter, Thompson, and Shaffer (1980), Black, Blumer, Wellner, Shepart, and Walker (1981), Brown, Chadwick, Shaffer, Rutter, and Traub (1981), and Chadwick, Rutter, Brown, Shaffer, and Traub (1981).