667 Phenylketonuria (PKU) as a paradigm for the dopamine-deficit hypothesis of ADHD: A case study

252

Abstracts

/International

Journal

Mean age and SD. was 11.1 + 2.7. . Using DSM - IV criteria 24 patients (60%) were diagnosed as conduct disorder, 10 patients diagnosed as ADHD and the other 6 (15%) had both diagnoses. Results showed that 10 patients (25%) had normal EEGs 24, patients (60%) had non spectic EEG changes and the other 6 (15%) had specific abnormal EEGs. Most frequent EEG positive findings was excitability in hyperventilation in 30 patients (75%), focal changes in 20 patients (50%), diffuse or intermittent slowing in 12 (30%) epileptiform activity in 8 (20%), abnormal asymmetry in 4 (10%) and low voltage in 2 patients (5%), No patient showed photic excitability.

665 EXG PARAMETERS TIONAL IMMATURITY

IN CHILDREN

WITH EMO-

L. Bozinovska’*, S. Mancevska’, J. Gligorovska’, E. Sivevska’, S. Bozinovski’ ‘Institute of Physiology, Medical Faculty, University of Skopje, Vodnjanska 17, Skopje, 91000 Macedonia; ‘Electrical Engineering Faculty, University of Skopje, Macedonia

The results of electrophysiological and psychological measurements of cognitive skills were compared l@ween two groups of children. The control group consisted of 20 healthy children aged 9.28. The experimental group was represented with 14 children aged 10.09 with emotional immaturity selected by the paediatric clinic. We used Electroexpectogram (EXG), Pattern Classification Learning test and Kohs test of intelligence. The EXG paradigm is electrophysiolo&al test for investigating the learning process based on the changes of the expectancy reflected by the amplitude of the CNV potential. EXG is an oscillatory curve which duration, number of cycles, amplitude, and reaction time depends on the cognitive effort of the subject. We analysed these parameters, IQ and the number of the iterations and errors in the Pattern Classification Learning test. There is statistical difference between the number of the cycles of the EXG curve (p < 0.051, their amplitude and the number of the iterations in the memory test. Children from the experimental group showed 1.071 cycles, and the control group showed 2.68 cycles. The results from the memory test are 18.38 iterations, for experimental and 10.89 for control.

666 EVENT RELATED POTENTIALS: IS THERE ANY RELATIONSHIP BETWEEN AMALGAM AND AT-IENTION DISORDERS? b 2 P. Gante@*, C. Basar-Eroglu’, R. Strietzel Institute of psychology and cognition research, University of Bremen, P.O. Box 330440, Bremen D-28334, Germany

of Psychophysiology300

(1998) 95-271

In this study we examine healthy subjects and patients, who are considered to have health problems (especially attention disorders) due to application of amalgam. All patients have been selected by their dentists. The aim of this study is to Iind out, if there is il a relationship between attention disorders and other health problems on the one hand and the fact, that these patients have amalgam fillings on the other hand and ii) whether it is possible to find a parameter in the morphology of event related potentials (ERPs), obtained from these patients either in the time or in the frequency domain, which correlates with the application of amalgam and/or attention disorders. The ERPs are recorded using an oddball paradigm with 15OOHz standard tones and 1550Hz target tones using randomly changing interstimulus intervals. The EEG is recorded from locations F3, F4, Cz, C3, C4, T3, T4, P3, P4, 01 and 02. Data is to be evaluated using the method of selective averaging in the time domain and in the frequency domain by means of Fourier- transformation. Also digital filters will be applied to look at special frequency bands.

667 PHENYLKETONURIA (PKU) FOR THE DOPAMINE-DEFICIT ADHD: A CASE STUDY

AS A PARADIGM HYPOTHESIS OF

M. Huss*, R. Bahadori, U. Lehmkuhl Charitt Campus Vimhow Humboldt University Berlin, Child and Adolescent Psychiatry, Platanenallee 23, 14050 Berlin, Germany Objective: Children with insufficient dietary treatment of PKU show cognitive deficits and psychopathological patterns similar to children with ADI-ID (Kalverboer et al., 1994). Research on both disorders revealed evidence for dopaminergic deficits in the prefrontal cortex. Based on these findings, methylphenidate (MPH) as the dopamine agonistic standard medication of ADHD should be an effective medication in children with PKU and symptoms of attention deficit, hyperactivity and impulsivity. Method: A nine year old boy with classic PKU was referred for diagnostic reasons in our multicenter ADHD project. Systematic research evaluation of ADHD symptoms (Canners’ Rating Scale, Child Behavior Checklist, structured interview) scored highest on all ADHD dimensions. Effects of treatment with MPH (1 mg/kg body weight) was systematically evaluated including Doppler radar assessment of motor activity (Huss et a., 1997). Results: Repeated clinical observations and questionnaire evaluations (Canners’ Rating Scale) show strong, highly MPH-related effects. Compared with non-PKU children of the ADHD-study effects were more pronounced and correlated to bioavailability of MPH. Conclusions: Extensive single case observations support the hypothesis of common dopamine deficits in ADHD and PKU.

Abstracts

/International

Journal

of Psychophysiology

30 (1998)

95-271

253

The theoretical link between both disorders opens new perspectives for the treatment of dopamine deficit related symptoms in PKU children.

C. Perchet*, L. Garcia&urea UPRES EA1880, University Claude Bernard, Hopital Neurologique, BP Lyon Montchat, 69003 Lyon, France

668 P300 HABITUATION, ATTENTION TRACTIBILITY IN CHILDREN

Aims of the study: i) To assess in normal children (6-9. years old) the different processing stage leading from stimulus evaluation to response execution during an attention shifting task (Posner paradigm). ii) In a 2nd time, to compare results in normals with those obtained in children with Attention Deficit Hyperactivity Disorder (ADHD). Subjects and Methods: 19 normal controls performed the task and ERPs (20 electrodes) were also recorded in 10. Subjects responded to left and fight visual targets by pressing the corresponding (left or right) mouse button (reaction times were measured). 80% of targets were preceded by a spatial cue, either valid (same side of the target) or invalid (opposite side). ERPs to both cues and targets were obtained by offline averaging of EEG epochs. Results and Conclusions: (1) Responses to cues were formed by early (Pl, loo-150 ms) and late (N2-P3,300-350 ms) components, identical in valid and invalid conditions. Thus, cues appeared to be processed as task-relevant stimuli and generated endogenous late potentials. (2) Attentional priming to correctly cued stimuli was reflected by enhanced Pl responses to taargets in the valid condition. (3) The “validity effect” (RT advantage for validly cued targets) seems related to a P3 latency “cost” in the invalid condition, rather than a “benefit” in the valid condition, since P3 latencies were identical to validly and no cued targets and both shorter than to invalidly cued targets. (4) A late positivity (Slow Wave) appearing only in the invalid and no-cue conditions, was likely to reflect the response selection stage. Its greater desynchronization in the no-cue condition may explain the longer RTs obtained in this condition, relative to the “invalid” situation. Preliminary data in ADHD patients suggest an important interindividual variability, both in behavioral performance (RT, error rates) and in ERPs. The most striking abnormalities observed so far are (1) An increase of errors, especially ‘false alarms’ to the cue; (2) Deficit in the processing of the cue, as shown by delayed P3 responses to the preparatory stimulus; (3) Deficit of attentional priming, as shown by lack of Pl enhancement to validly cued targets, and (4) A disappearance of the P3 latency differences between invalid and uncued targets.

AND

DIS-

R. KiIpelainen*, L. Luoma, E. Herrgard, A. Koistinen, J. Karhu, J. Partanen Kuopio University Hospital, Dept. of Clinical Neurophysilogy, P.O. Box 1777, Kuopio, 70211 Finland Improved resistance to distraction characterizes development of selective attention in children. Various experimental studies show that children use their attentional capacity in the processing of irrelevant information more than adults do. Children may also have difficulty inhibiting responses to irrelevant stimuli. Habituation of the P300 event-related potential (ERP) amplitude has been shown to be sensitive to the amount of attentional resources allocated in stimulus processing, with more habituation occuring in easy tasks than in more difficult tasks in adults. The aim of the present study was to assess the relationship between distractibility and the change in the amount of attentional resources allocated in the stimulus processing during a discrimination task in children. The P300 ERP was elicited with an auditory discrimination (oddball) paradigm in 80 healthy 9 year-old children. Consecutive blocks of stimuli were obtained to assess habituation of the P300 amplitude. The ability to resist distraction was assessed using the “Freedom From Distractibility” (FFD) factor of the Wechsler Intelligence Scale for Children-Revised (WISC-R). Children susceptible to distraction (FFD score I 16) demonstrated hardly any habituation of the early part of the frontally recorded P300 (“P3a”), whereas in children with better ability to resist distraction (FFD score 2 20) this early part of the P300 habituated, and the later part of the P300 (“P3b”) became more dominating towards the end of the task. A short latency, frontally distributed P300 (“P3a”) is usually recorded in response to novel stimuli. The failure to demonstrate habituation of this component suggests that children susceptible to distraction process the target stimuli as “novel” input throughout the discrimination task. The finding may suggest that the ability to build up a neural representation, i.e. a “sensory memory trace”, for the target tone is impaired in these children, a finding in accordance with some behavioral studies showing impaired sensory memory in easily distractible children. The findings of the present study may provide further insight into the developmental aspects of attention and distractibility in children.

669 VISUO-SPATIAL ATTENTION SWITCHING IN CHILDREN: AN ELECI’ROPHYSIOLOGICAL STUDY USING THE ‘POSNER’ PARADIGM

670 THE CHANGES OF SUSCEPTIBILITY TO THE DEVELOPMENT OF IN VITRO KINDLING LIKE AUDIOGENIC SEIZURES

Alexey Semyanov* , Emil Morenkov, Oleg Godukhin Institute of Theoretical and Experimental Biophysics of Rus. Acad. of Scien., Pushchino, Moscow Region, 142292 Russia