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Biomedical subjects

P Laursen

Publications and source records attributed to P Laursen.

18 recordsLinked to original sources
PubMed2002

The influence of hormone replacement therapy on the aging-related change in cognitive performance. Analysis based on a Danish cohort study.

OBJECTIVE: A maintenance and/or improvement of cognitive performance with postmenopausal hormone replacement therapy (HRT) is biological plausible. The objectives of this study were to analyze the impact of HRT on aging-related changes in cognitive performances, and to assess whether women who choose HRT have better cognitive performance prior to HRT. METHODS: Data derives from a longitudinal sub-cohort of women participating in a large survey of the general adult population-The Danish MONICA (MONItoring CArdiovascular risk factors) Study. Main variables for analyses come from neuropsychological examination consisting of 28 cognitive parameters collected in 1982-1983 and again in 1993-1994, by a computer-aided test technique, the Cognitive Function Scanner((R)). The final analyses comprised 126 'never users', 40 'current users' at follow-up, and 30 'future users' of HRT (women who started HRT during the observation period subsequent to baseline registration). RESULTS: 'Current users' of HRT at follow-up showed a less pronounced decline in cognitive performance compared to 'never users' in one of six parameters for concentration ability and two of eight parameters for visuomotor function. 'Future users' of HRT had better cognitive performance at baseline compared to 'never users' in long-term visual memory, concentration, and reaction time. 'Future users' of HRT were more precise but spent more time in the tests for visuomotor function than 'never users'. CONCLUSION: HRT-treated women show a postponed aging-related decline in cognitive functioning, partly in concentration and partly in visuomotor function. However, women who choose HRT have better cognitive performance prior to the treatment.

Adult↗
PubMed1999

[A quality assessment of notified occupational diseases submitted to the National Occupational Environment Service].

The aim of this study was to assess the quality of a consecutive sample of occupational disease notifications submitted to the National Working Environment Service during 1994. The sample consisted of 860 notifications describing occupational diseases among persons working in companies situated in the county of Vejle. The data information e.g. company name and address, time of employment, harmful exposure and disease, were registered. An overall data quality assessment was performed including evaluation of the etiological connection between described occupational exposure and disease and potential preventive perspectives. The study showed that the notified informations in general were adequate, but doctors need to pay more attention to dose description of the harmful exposure. About 80% of the notifications presented an adequate connection between occupational exposure and disease. Only half of the notifications described preventable and recent (less than five years) harmful exposure. In conclusion, the Danish occupational disease notification system is in general of a high standard, and the National Working Environment Service could make more use of doctors' information provided in these notifications.

Cross-Sectional Studies↗
PubMed1999

Risk of chronic effects on the central nervous system at low toluene exposure.

This study evaluates the chronic effects on the central nervous system of exposure to low concentrations of toluene (TWA < 20 ppm) on workers in a rotogravure plant. Ninety-eight male workers from a selection pool of 107 (92%) were examined neuropsychologically using a Cognitive Function Scanner, and neurologically by computerized methods measuring co-ordination ability, tremor and position stability. In addition measures of symptoms and former exposure were obtained by questionnaire. The workers were divided into three groups: Group 0 with no exposure to organic solvents (n = 19); Group 1 with exposure to TWA < 20 ppm of toluene for less than 13 years (n = 30) and Group 2 with exposure for more than 12 years (n = 49). Within Group 2, 37 (75%) had been exposed at levels exceeding 100 ppm for 10+ years before 1983. No significant differences were found between Group 0 and Group 1 regarding symptoms and results of the applied tests. Group 2 differed significantly from the two other groups in scoring higher on a symptom index (p = 0.04), particularly regarding concentration ability, reduced memory and fatigue. Group 2 scored significantly poorer on tests for visuospatial function, number learning and word recognition, while no differences regarding neurological functions were observed. The study showed no differences regarding neuropsychological and neurological functions between a non-exposed group of male workers and workers exposed to toluene less than 13 years at TWA < 20 ppm. However, long-term exposure to TWA (time weighted average) of toluene exceeding 100 ppm was associated with impaired neuropsychological function.

Central Nervous System Diseases↗
PubMed1997

The impact of aging on cognitive functions. An 11 year follow-up study of four age cohorts.

The literature on longitudinal studies of aging and cognitive performance is reviewed. The review reveals some ambiguity which seems primarily to be due to selection bias in the study groups and insufficient statistical modelling and parameterization. The main purpose of this study was to analyze the impact of aging on cognitive performance of the general adult population. In addition, the following problems are considered: If an aging impact is found, is it then evenly distributed across different age cohorts and different cognitive functions? Is the effect of different subject-related and situational factors on the test parameters stable over time? Is it possible to eliminate the impact of the examiner in cognitive testing? Moreover, do certain background factors such as age (generation), sex, schooling, etc. or test performance in an earlier examination have predicting power for the participation at a later stage in the study? The analysis was made using a longitudinal design with four successive age cohorts born in 1952, 1942, 1932, and 1922. 1,026 subjects were examined in 1982-83 and 711 were re-examined in 1993-94. At both occasions the subjects were tested by means of the Cognitive Function Scanner method. Attrition was found in all four age cohorts but most profound in the oldest cohort. Attrition occurred most frequently among subjects with only primary schooling and low social status. Age (generation), Sex, Schooling, Occupational Activity Status, Smoking Status, Psychic Stress, and questionnaire positive Cardiovascular Disease in the 1982-83 study all had significant relation to non-participation in the follow-up, either because of death, refusal to participate or because the subjects did not turn up on the agreed date for examination. Also a few test parameters, primarily in the attention tests and concentration tests, were found to be significantly related to non-participation in the follow-up. The results of the follow-up study, in which each subject was his own reference, showed two different tendencies. One tendency indicated some decline in performance. It was found in parameters for non-verbal learning and memory, retention of verbal memory, visuomotor and visuospatial speed, concentration, and reaction time. The other tendency indicated some improvement in performance in relation to verbal learning and memory, visuomotor and visuospatial precision, and to visual perception. It was a general tendency that performance becomes more scattered with increasing age. The follow-up study showed that Generation, Sex, and Schooling are the most important subject-related factors to take into consideration in the evaluation of test results. The significant impact of the Generation factor indicates that cognitive performance depends not only on aging but is also modulated to a large extent by generation specific factors. In spite of intensive training and special focus on communication it was evident that the situational Examiner factor plays a significant role in all of the cognitive tests. The strong impact of the Examiner factor makes the use of test norms questionable. Norms should be used only as rough guidelines. In the individual psychological assessment, focus should be on the subject's problem solving strategies. This can be reached by supplementing the traditional psychometric scores with a range of response process observations obtained by recording the natural steps of the subject's response flow combined with latencies for each step, and analyzing the response chains by pattern analysis. The computer is considered the most appropriate tool for recording response flows.

Adult↗
PubMed1994

Response classification in psychological testing using a neural network.

A feedforward neural network with error backpropagation has been designed to recognize hand-drawn patterns in a cognitive test. The architecture uses both position and direction sensitivity in the input layer. The training set consisted of 659 icons which were shifted horizontally and vertically to give a total training set of 5931 icons. In testing on an independent set of 31,192 icons produced by 557 subjects from a Danish standard population sample, the rate of misclassification was 0.12% compared with an average rate of sequence errors of 1.6%.

Humans↗
PubMed1994

Event detection on patient monitoring data using Causal Probabilistic Networks.

Applications are described of the knowledge-representation technique Causal Probabilistic Networks for the detection of events related to the patient and the monitoring equipment, in the context of intensive care patient monitoring. The purpose of the event detection is to reduce the number of false alarms generated by the patient monitor, and to generate alarms related to patient or equipment events rather than to threshold violation. A PC-based system has been developed and tested on patient data. A system for real-time use in patient monitoring is under development.

Diagnosis, Computer-Assisted↗
PubMed1990

A computer-aided technique for testing cognitive functions. Validated on a sample of Danes 30 to 60 years of age.

With the growing importance of occupational behavioural neurotoxicology the demand for a standardized and reliable cognitive test battery has become urgent. The present study deals with the compilation of a test battery, the purpose of which is to be sensitive to mild brain dysfunction and suitable for modern microcomputer administration and scoring. The battery comprises tests of learning and memory functions specific for each brain hemisphere (Face Recognition Test and Number Learning Test), visuomotor function separately for continuous and discrete tasks (Figure Drawing Test and Pen-to-Point Test), visuospatial function (Parallelogram Test), visual and auditive perception, attention and vigilance (Bourdon-Wiersma Test and Continuous Reaction-Time Test), and concentration (Continuous Graphics Test). The complete test battery was administered and scored on a slightly modified Tektronix 4052 computer with a Tektronix 4956 digitizer as a peripheral device. The validity of the battery was analysed on the basis of a sample of the normal Danish population (N = 1262) stratified for the ages 30, 40, 50, and 60 years, the two sexes, and residence in one of 11 municipalities in the western part of Copenhagen County. Using a 16-dimensional multivariate model comprising biological, social, psychological, and environmental factors, and also examiner behaviour, statistical analyses confirmed hypotheses of influence by the factors Age, Sex, Schooling, and Social Group, i.e. these factors partially explained the variance in the case of almost all the test parameters. Moreover, psychic stress, as determined in a questionnaire, had explanatory power with tests demanding attention and concentration. Hypotheses of effects on test performance by Smoking Status and psychophysiological diurnal or annual rhythms, i.e. Time of Day, and Time of Year, were confirmed for a few parameters, but the effects differed to some extent from those described in the literature. Alcohol Consumption, Drug Consumption Affecting the CNS, Cardiovascular Diseases or Disorders, Metabolic Diseases or Disorders, CNS Injuries or Disorders, and Occupational Activity Status, all revealed by questionnaire, were not found to show the assumed significant effects on test performance. However, a hypothesis of an effect originating in differences between different examiners' behaviour was confirmed for a number of test parameters, although all the test measurements and scorings were done automatically by computer. On the basis of a re-examination of 19 patients previously diagnosed as suffering from diffuse organic psychosyndrome, the sensitivity of the test battery was estimated to be 0.79. The specificity was estimated to be 0.79 on the basis of the results of the original sample.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1981

Incidence and prevalence of ischaemic heart disease among urban busdrivers in Copenhagen.

A 5-year follow-up study was conducted among all male busdrivers in Copenhagen, Denmark, in addition to the cross-sectional study. In the follow-up study, the SMR for death due to ischaemic heart disease (ICD 410-414) was 144 and SMR for first clinical episode of acute myocardial infarction (ICD 410) was 139, with men in Copenhagen as controls. 80% of the busdrivers (1396 men) participated in the cross-sectional study. The prevalence of questionnaire-positive angina pectoris was 4.9%; in all age groups this was higher than among the controls, locomotive drivers in Denmark. The high health-related selection of busdrivers is assumed to cause an underestimation of the relative occurrence of ischaemic heart disease. Possible explanations for the findings in this study are discussed.

Adult↗
PubMed1979

Meniere's disease: a neuropsychological study II.

23 Meniere patients were examined with an extensive battery of neuropsychological tests. In a previous investigation the authors had demonstrated that patients with a long duration of Meniere's disease had psychological disturbances, presumably localized in the nondominant hemisphere. In the present investigation the patients had a short duration of the disease, and we were unable to reproduce the psychological disturbances. It is concluded that the central changes in the nondominant hemisphere function develop over a long period of time. It is hoped for that further neuropsychological investigations of Meniere patients can give more information of what is primary in Meniere's disease: peripheral sensory or central neurological changes.

Adult↗
PubMed1978

Menière's disease. II. A neuropsychological study.

23 Menière patients were examined with a extensive battery of neuro-psychological tests. In a previous investigation, the authors had demonstrated that patients with long-duration Menière's disease had psychological disturbances, presumably localized in the nondominant hemisphere. In the present investigation, the patients had short-duration Menière's disease, and we were unable to replicate the results of the former investigation. It is concluded that the central changes in nondominant hemisphere function develop over a long period of time. It is hoped for that further neuropsychological investigations of Menière patients will give more information on what is primary in Menière's disease: peripheral, sensory or central neurological changes.

Adult↗