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Biomedical subjects

S E Levander

Publications and source records attributed to S E Levander.

At least 19 recordsLinked to original sources
PubMed1992

Exploring the connections between platelet monoamine oxidase activity and behavior. II. Impulsive personality without neuropsychological signs of disinhibition in air force pilot recruits.

Platelet monoamine oxidase (MAO) activity and serum levels of the adrenal androgen metabolite dehydroepiandrosterone sulfate (DHAS) were measured in 18 male air force pilot recruits and 19 randomly selected male conscripts. Personality scales from three inventories were given, and computerized neuropsychological tests were performed: finger tapping and alternation, reaction time, perceptual maze, perspective fluctuation and lexical decision. The pilot recruits had higher scores in sensation-seeking-related scales suggesting disinhibited behavior in the social sphere, interest in sports and activities involving some danger, and a need for change. They also had higher scores on an impulsivity scale which comprises sensation-seeking content. In the neuropsychological tasks, the pilot recruits were faster in finger-tapping alternation and performed more efficiently in the perceptual-maze test than the conscripts. In a linear discriminant analysis, neuropsychological-task performance discriminated significantly between the pilot and conscript groups. In the biochemical measures, the pilot recruits had higher DHAS levels but similar MAO activity levels compared to the conscripts, which is in contrast to what has been found in other sensation-seeking groups in comparison to controls. This result is in accordance with the normal scores in one of the impulsivity scales in the pilot recruits, and with the absence of signs of disinhibition in neuropsychological tasks. It is proposed that only some aspects of the impulsivity concept might be critical for the association with low MAO activity.

Adolescent↗
PubMed1990

Electrodermal responsivity in young hypotensive and hypertensive men.

Electrodermal responses were recorded during the presentation of 16 moderately intense (1000 Hz, 90dB) tones in three groups of young men: borderline hypertensives (138/79 mmHg), normotensives (112/65 mmHg), and hypotensives (104/63 mmHg). Electrodermal response habituation was measured as a decline in response over trials, number of trials to a response criterion of three successive nonresponses, and number of inversions of response amplitude (larger responses following smaller responses) in the stimulus sequence. Habituation was fastest in hypotensives. Nonspecific electrodermal responses at rest and during tone presentations were most frequent in borderline hypertensives, least frequent in the hypotensive group, with the normotensive group falling in between. There were no significant differences in electrodermal level. The rapid habituation rate in hypotensives is discussed in terms of cursory information processing associated with impulsive behaviour. The higher nonspecific electrodermal activity in borderline hypertensives is interpreted to indicate increased sympathetic nervous system activity.

Adolescent↗
PubMed1989

Birth stress, handedness and cognitive performance.

Information regarding conditions during pregnancy and delivery was obtained by extensive interviews with mothers to left-handed and right-handed students. Using the same criterion as van Strien, Bouma and Bakker (1987) for defining birth stress, the present study did not replicate their findings of higher frequency of reported birth stress in left-handers. The difference in outcome was ascribed to differences in recruitment of subjects, the present sample constituting a majority of left hand writers from a population of 921 students, while the van Strien sample was less well defined. The present study was extended by comparing left-handed and right-handed subjects (separated for sex) with and without birth stress, on verbal and nonverbal abilities, and on eye dominance, early learning difficulties and familial sinistrality. Left eye dominance was more frequent in male left-handers with birth stress. Birth stress alone had negative effects on cognitive performance, different for males and females.

Adult↗
PubMed1987

Neuropsychological correlates of platelet monoamine oxidase (MAO) activity in female and male subjects.

Platelet monoamine oxidase (MAO) activity has been found to have behavioral (psychiatric and personality) correlates and is assumed to be linked to central transmitter systems and thus presumably to neuropsychological processes. In the present study, computerized neuropsychological tests, a reaction time (RT) test and a visuo-spatial problem solving test, the Perceptual Maze Test (PMT), were given to 32 female and 29 male students, each sex group divided into three subgroups on the basis of platelet MAO activity. The tests yield measures of laterality (reaction time for left- versus right-sided stimuli) and different aspects of cognitive strategy and skill, e.g. time used for inspection of the maze, for processing the stimulus pattern, and for checking the correctness of solutions. Low MAO female subjects had shorter RTs, pronounced for left-sided stimuli, and shorter inspection times in the PMT compared to other female subjects. Low and high MAO males had difficulties in inhibiting responses, when required, and low MAO males were more rapidly prepared to respond to new stimuli after short intervals than other males. In the PMT, high MAO male subjects spent a smaller part of the total time on inspection in relation to other male groups and had more rubouts than low MAO males, whose maze solving behavior indicated higher visuo-spatial ability. The results are discussed in terms of possible neurochemical bases of impulsivity and psychopathy, and of spatial skill.

Adolescent↗
PubMed1987

Skin conductance nonresponding and nonhabituation in schizophrenic patients.

Bilateral skin conductance (SC) and heart rate (HR) were measured for 18 RDC diagnosed schizophrenic patients during rest and during presentation of identical tones. Computed tomography scans were evaluated. All but two patients were on neuroleptic medication. Six patients were nonresponders, seven habituated to the tones and five were nonhabituators. Nonresponders had lower SC level, fewer SC spontaneous fluctuations and higher HR level than the other subgroups. On neuropsychological tests the performance of the habituator group was closest to that of healthy subjects. Nonresponders did not differ in clinical symptoms, anamnestic data or in the prevalence of psychiatric morbidity in their families. Seventeen percent of the nonresponders had poor premorbidity adjustment vs 80% of the nonhabituators. Nonhabituators had higher ranks in the following symptoms: Presence of commenting voices, and inability to feel. They also tended to have wider third ventricles than the other two subgroups. The results support earlier findings in our laboratory suggesting nonhabituators as an important subgroup among schizophrenic patients.

Adult↗
PubMed1987

Magnetic resonance images related to clinical outcome after psychosurgical intervention in severe anxiety disorder.

Postoperative verification of radiosurgical lesions in white matter has been difficult to obtain with CT. With magnetic resonance (MR) imaging, however, lesions could be demonstrated in patients undergoing a psychosurgical procedure, gamma capsulotomy, for anxiety disorder. The appearance and location of the lesions were related to the irradiation dose and to the long-term clinical outcome studied prospectively by two independent evaluators who had not been involved in the selection or the treatment of the patients. Seven consecutive cases were examined. CT was also included for comparison reasons. Lesions were clearly visible with MR in patients who improved after surgery. Conversely, lesions were inadequate in cases who did not benefit. MR proved to be more accurate than CT both in detecting the lesions and in defining their configuration. The observations argue for the use of MR for post-operative verification of radiosurgical lesions. MR may facilitate the determination of a clinically effective radiation threshold estimate for radiosurgical lesions, which should be of value for the planning of studies of this type of limbic system surgery.

Adult↗
PubMed1987

Cognitive sex differences: speed and problem-solving strategies on computerized neuropsychological tasks.

Skill, strategy, and laterality measures obtained through computerized neuropsychological tasks, a reaction time (RT) test, and a visuospatial problem-solving test, the Perceptual Maze Test, were analyzed in relation to sex and handedness of 56 high-school students. Boys were significantly faster than girls on most RT subtasks (including a response-inhibition task) and made more two-choice RT response errors for right-sided stimuli, which may be interpreted as resulting from a less cautious strategy. In maze performance, boys were superior to girls. An analysis of separate phases of the maze-solution process suggested that boys preferentially used an impulsive-global strategy. Girls, using a more reflective-sequential task-solving strategy, were significantly slower, without hitting more targets. Compared to all other groups, left-handed girls (strongly left-handed) had lower performance on maze tasks with no target information, particularly in left-sided solution pathways. Results were interpreted as reflecting differences in hemispheric competence and activation patterns between the sexes. Signs of a less differentiated lateralization and slight dysfunction of visuospatial skills in the left-handed girls were discussed.

Adolescent↗
PubMed1985

Smooth pursuit eye tracking, neuropsychological test performance, and computed tomography in schizophrenia.

Smooth pursuit eye movements (SPEM) were measured in 18 patients who met Research Diagnostic Criteria for schizophrenia. Some degree of SPEM impairment was present in most patients. Deviant eye tracking was not related to ratings of severity of illness, but was related to recurrent episodes of hospitalization, antipsychotic medication, and lower ratings in anxiety and delusions. Worse SPEM tended to be associated with larger lateral ventricles as assessed on computed tomography. Three patients with reversed occipital asymmetry had more deviant eye tracking than the remaining patients. Eye movement impairment was related to worse performance in Finger Tapping and in the Trail-Making Test, and to fewer perceived alternations of a Necker cube, suggesting that frontoparietal disturbances are related to poor pursuit eye tracking in schizophrenia.

Adult↗
PubMed1985

Regional cortical dysfunction in schizophrenic patients studied by computerized neuropsychological methods.

18 RDC-diagnosed schizophrenic patients (11 men, 7 women) were compared to 84 normal men with three computerized neuropsychological methods, assumed to reflect lateralized and frontal cortical functions: (1) Bilateral Finger Tapping and Finger Alternation, (2) Bilateral Trail Making, and (3) passively perceived Necker cube reversals. Schizophrenics differed from normals by (1) inferior Tapping/Alternation but only in the right hand, (2) inferior Trail Making, most pronounced for Form B, and (3) lower frequency of Necker cube reversals. Patients with previous neuroleptic medication and prior psychiatric hospitalizations were inferior in Trail Making and had fewer Necker cube reversals. The findings were interpreted in line with recent models of schizophrenia involving a left-hemisphere dysfunction/over-activation and a frontal dysfunction.

Adult↗
PubMed1984

Bilateral skin conductance activity, clinical symptoms and CSF monoamine metabolite levels in unmedicated schizophrenics, differing in rate of habituation.

Bilateral skin conductance (SC) and heart rate (HR) were recorded for 18 RDC-diagnosed unmedicated recently admitted psychotic patients (13 schizophrenic and 5 paranoid) and for age- and sex-matched controls, during rest and tone stimulation (85 dBA, 1000 Hz, 1 sec duration and 0.25 msec rise time). Schizophrenics had more SC spontaneous fluctuations and faster HR, indicating higher arousal. SC spontaneous fluctuations were more frequent in left hand and showed an increasing trend over the session. Several SC measures indicated higher responsivity and a more irregular responding pattern in schizophrenics. These patients had higher levels of the noradrenaline metabolite (MHPG). Paranoid psychotic patients had a more stable SC habituation course than controls, and higher levels of the dopamine (HVA) and serotonin metabolites (5-HIAA). Schizophrenic nonhabituators had fewer positive psychotic symptoms than habituators, suggesting that poor habituation is not due to interference by symptoms. It may be related to higher arousal, or to deficient information processing.

Adult↗
PubMed1983

Smooth pursuit eye movements, clinical symptoms, CSF metabolites, and skin conductance habituation in schizophrenic patients.

Smooth pursuit eye movements (SPEM) for two stimulus velocities (sinusoidal and triangular) were studied by visual inspection in 12 unmedicated RDC-diagnosed schizophrenic patients and in 13 matched controls. SPEM was worse in the patient group and their performance deteriorated with repeated presentations of the task. Patients with previous antipsychotic medication, previous hospitalization, higher age, late onset of manifest psychotic symptoms, and few positive psychotic symptoms had worse SPEM according to the Comprehensive Psychopathological Rating Scale. Subjects with poor SPEM showed slower habituation of skin conductance responses. There were no correlations between SPEM ratings and levels of CSF monoamine metabolites HVA, 5-HIAA, and MHPG.

Adult↗
PubMed1978

Necker cube reversals, arousal and psychopathy.

Necker cube reversals were studied in a group of 24 arrested men in three experimental sessions; two weeks, one week and immediately before trial. The first session was assumed to represent a moderate laboratory stress due to the novelty of the situation, and the last session a real-life stress associated with anticipation of appearing in court. Both were superimposed on the sustained real-life stress of being in jail. There were no stress-related changes between the three sessions in the rate of apparent change (RAC) of the Necker cube. The intra-individual stability of RAC was extremely high. There were significant positive correlations between RAC in all sessions, and a psychopathy-related inventory scale, the Gough delinquency scale.

Adolescent↗
PubMed1976

Piracetam-induced improvement of mental performance. A controlled study on normally aging individuals.

A double-blind, intra-individual cross-over comparison of the mental performance of 18 aging, non-deteriorated individuals during two 4-week periods of piracetam (1-acetamide-2-pyrrolidone) and placebo administration was performed using conventional and computerized perceptual-motor tasks. In a majority of these tasks the subjects did significantly better when on piracetam than on placebo, a finding consistent with ratings completed by two independent observers. The findings indicate new avenues for the treatment of individuals with reduced mental performance possibly related to disturbed alertness--a neglected group of psychiatric conditions.

Aged↗
PubMed1975

Does piracetam counteract the ECT-induced memory dysfunctions in depressed patients?

A double-blind, intra-individual cross-over comparison of the effect of piracetam on retrograde memory impairement as measured by the KS memory test battery was performed in connection with second and third Bi-ECT in 18 patients diagnosed as suffering from depression. The seizure duration and the post-ECT EGG patterns were examined visually and the post-ECT confusion time was measured. Piracetam was given orally in the dose of 4.8 g/day for 3 days. No significant effects were obtained on memory scores, electrical stimulus duration, EEG pattern or post-ECT confusion time. The findings may indicate that the protective effect of piracetam shown in animal electroconvuslive stimulation (ECS) is due to a counteraction of the disturbing effect of hypoxia on memory functions. It is concluded that more information is needed as regards the pharmacokinetics and the mode of action of the drug.

Adult↗