Dementia, learning and the P300 paradigm.

This investigation was designed to measure learning effects in demented patients, using psychophysiological methods. Twenty-five patients with vascular dementia and 25 age-matched controls were investigated with a P300 and reaction-time paradigm. The repetition of the cognitive process discriminating between different sizes of circles led to a significant decrease in P300 latency and in reaction time. It was therefore concluded that such a paradigm is able to measure learning effects, and also that vascularly-demented patients can improve their performance on such tasks.

The value of P300 in the diagnosis of cognitive impairment in stroke.

The latency of the P300 and the simple reaction time (RT) generated by visual stimuli were investigated in a group of 43 healthy normals and in 24 stroke patients. The stroke patients were in a chronic phase of their disease. Twelve patients were without cognitive deficit, while 12 showed the symptoms of dementia. In the normals, P300 and RT showed a positive correlation with age. In comparing 12 age-matched normals with stroke patients with and without dementia, a similar latency of the P300 was found in the normals (347 msec) and in the stroke patients without dementia (349 msec). The patients with cognitive impairment showed a significant increase in their latency (434 msec). The RT was significantly different in the normals (421 msec) and stroke patients without dementia (533 msec) as well as in the stroke patients with dementia (663 msec). A significant correlation between the P300 and the RT was found.

[Coping with stress and blood viscosity in stroke prevention patients]. / Stressverarbeitung und Blutviskosität bei Schlaganfallvorsorgepatienten.

INTRODUCTION: Hematocrit, fibrinogen and blood viscosity influence blood fluidity and are well known stroke risk factors. Studies have shown relationships between these factors and psychological stress. AIM: The aim of this study was to investigate how stroke risk patients with increased hematocrit, increased fibrinogen, or increased plasma viscosity differ from patients free of these risk factors in their ways of stress coping. METHOD: 6503 persons participated in the following stroke risk investigations: biographical and risk factor orientated anamnesis, neurological status investigation, laboratory investigation, sonographic investigation and psychological investigation. After assessment of several risk factors, differences in stress coping between risk factor and non-risk factor groups were investigated by means of the t-test and the Wilcoxon-test. RESULTS: Men with pathological hematocrit showed significantly higher scores in the coping strategy resignation and a tendency to less positive self instruction and response control attempts. Women with higher values of hematocrit demonstrated higher values in resignation and drug intake. Men with higher fibrinogen showed significantly higher scores in distraction, vicarious satisfaction, minimising by comparison and tendency to flee as well as a tendency towards drug intake. Women with increased fibrinogen showed no differences. Men with normal plasma viscosity had significantly higher values in tendency to flee and tendencially in desire for social support and lower values in minimising by comparison. Women with increased plasma viscosity demonstrated higher scores in resignation and aggression. CONCLUSIONS: The presence of elevated values in parameters of blood viscosity coincides with increased passive and defensive coping mechanisms, whereas non-risk factor persons show raised values in active coping styles.

[Stress management in heart diseases, obesity, nicotine and alcohol use]. / Stressverarbeitung bei Herzkrankheiten, Ubergewicht, Nikotin- und Alkoholkonsum.

INTRODUCTION: Heart diseases, obesity, nicotine and alcohol abuse are all relevant stroke risk factors. Some studies refer to stress stimuli and coping strategies as modulators for stroke risk factors. AIM: This study investigated differences between stroke prevention patients with heart complaints, obesity, nicotine or alcohol abuse and stroke prevention patients without these risk factors. METHOD: 5993 stroke prevention patients participated in a medical-psychological stroke risk investigation at the Christian Doppler Clinic in Salzburg. The differences in coping strategies between groups of patients with risk factors and groups without were investigated by means of multivariate analysis of covariance. RESULTS: Significant differences in stress coping were found for every risk factor (split by sex). Men suffering from heart diseases showed higher values in the coping strategy tendency to flee. Women with heart complaints demonstrated significantly lower values in minimising by comparison. Obese/adipose patients performed significantly higher values in the coping strategies vicarious satisfaction and aggression (men). Nicotine abusing prevention patients showed significantly higher values in drug intake and lower scores in continued thoughts. Non-smoking men furthermore reached higher values in vicarious satisfaction and non-smoking women in minimising. Persons not consuming alcohol demonstrated higher drug intake and aggression (men). Wine drinkers showed lower scores of self-pity and increased situation control attempts (women). CONCLUSION: Prevention patients with risk factors demonstrated significant differences in coping strategies in comparison to those without risk factors. Persons with heart diseases demonstrate a more defensive behaviour. The risk factors obesity, nicotine and alcohol consumption are associated with a risk factor supporting stress coping behaviour. The modification of the coping strategies drug intake and vicarious satisfaction towards a more active confrontation could probably influence various risk factors (nicotine, alcohol consumption, obesity) simultaneously.

[Recognition of pitch of sinusoidal half waves. A contribution to auditory theory]. / Uber die Erkennbarkeit der Tonhöhe von Sinushalbwellen. Ein Beitrag zur Hörtheorie.

A total of 24 students (mean age 21.7 years) were asked to identify the frequency of sinusoidal half-waves. Four different frequencies (f1 = 400, f2 = 600, f3 = 800, f4 = 1000 Hz) and four different types of half-waves were generated by a computer-controlled device. Stimuli were presented binaurally via headphones. The results show that the mean threshold for recognizing different frequencies is 2%-10%. As this low value indicates, the human auditory system exhibits a remarkable ability to process fragments of sinusoidal waves.

[P300 and dementia: diagnostic relevance II]. / P300 und Demenz: Diagnostische Relevanz II.

Recent research on the relationship between ERP-latencies and reduced information process capabilities with demented subjects has yielded divergent results. In the present study P300-latencies and RT are used in an attempt to differentiate between demented and nondemented subjects. Based on the "feature-integration-theory" of Treisman an experiment was designed in order to investigate more complex cognitive processes. The results showed that both P300-latency and RT may be used as additional diagnostic indices for cognitive capability.

[P300 and dementia: diagnostic relevance. I]. / P300 und Demenz: Diagnostische Relevanz I.

Visual evoked potentials, including the P300 response, and reaction time were recorded from 20 patients with multi-infarct dementia, 20 nondemented patients with brain-infarct diseases, and 20 age-matched control subjects. Additionally the patients were assessed using the WAIS-index. Prolonged P300 latency and reaction time occurred in both of the patient-groups, correlated significantly with the WAIS-index. However, effects regarding to P300 latency and reaction time were not strong enough to allow individual classifications.

[Tachistophony, a measuring method for time threshold in hearing. A contribution to hearing theory]. / Tachistophonie, eine Messmethode für eine Zeitschwelle beim Hören. Ein Beitrag zur Hörtheorie.

Tachistophony is presented as a method of measuring time-thresholds for understanding spoken signals and for recognising sound levels. The minimum total-time of periodically interrupted sound-events per second is assessed. The pause-total can reach a value between 4 and 9 times (in extreme cases up to 14 times) the sound flow period. The total of sound-pulses is measured only at 250 to 100 ms, with the recognition of values still operative. Due to the low information-content of numerical words their time-threshold is the lowest. The time-threshold lies considerably higher for one-syllable words and sentences with a higher information-content. The superiority of the left ear with dichotic stimulation is confirmed with monaural tachistophonic stimulation. These values are related to phase-frequencies of between 13 and 40 Hz. When the phase-frequency is lowered, comprehension below 8 Hz falls considerably. This is less apparent with phase-frequencies between 40 and 110 Hz.

[Polygraphic studies of newborn infants at risk using acoustic stimulation close to and above the threshold level]. / Polygraphische Untersuchungen von Risikoneugeborenen bei schwellennaher und überschwelliger akustischer Reizung.

16 newborns were investigated by means of polygraphy (EEG, respirography, heart rate, psychogalvanic reflex and behavioural observations). They were acoustically stimulated (125, 750, 15000 and 3000 Hz, with stepwise increase of the intensity by 10 dBA) during the period of quiet sleep. Partial vegetative reactions appeared in 11 newborns between a stimulation intensity of 30 to 50 dBA. Changes of breathing were initially observed. A further increase of intensity caused reactions in heart rate, psychogalvanic reflex and also body movements. The EEG and behavioural states were never changed at this level of intensity. Reactions in these parameters were recurrently observable if stimulation intensity was higher than 80 dBA. Only half of all stimulations were followed by reactions. The results verify decreased threshold intensity to evoke partial vegetative reactions in newborns at risk and the same sequence of additional reactions in EEG and behavioural states as in healthy newborns following increasing stimulation intensity.

[Blood lipids and adaptation to stress as risk factors for stroke prevention]. / Blutfette und Stressbewältigung als Risikofaktoren in der Schlaganfallvorsorge.

Do stroke prevention patients with increased blood-fat-protein compounds (total cholesterol, HDL- and LDL cholesterol and triglyceride) have a different method of coping than patients with normal blood fat? 1159 stroke prevention patients participated in the following stroke risk investigations at this hospital: biographical and risk factor-orientated anamnesis, a neurological status investigation, a laboratory investigation, a sonographic investigation and a psychological investigation. The differences in the coping strategies of those patients with normal and those with higher blood-fat-protein compounds were investigated. Patients with higher total cholesterol showed significantly higher values in the avoidance of stress situations (sig. 0.041) and a stronger tendency towards escapist behaviour (sig. 0.05). Patients with normal HDL cholesterol values indicated a tendency (sig. 0.07) to higher values in positive self-instruction in comparison to patients with reduced HDL cholesterol values. Those prevention patients with higher LDL values showed a tendency (sig. 0.08) to higher values in the intake of narcotic substances (nicotine, alcohol, tranquillisers, pharmaceutical agents). Patients with increased triglyceride indicated significantly higher values in coping by compensation (eating, shopping, reward behaviour, watching TV; sig. 0.037) and the intake of narcotic substances (sig. 0.044). Prevention patients with higher total cholesterol, LDL/HDL, or triglyceride values showed significantly different coping strategies in comparison to those patients with normal values. Increased avoidance and escapism behaviour and also compensation and the abuse of narcotic substances could be seen in connection with an increase in the risk of a stroke. In contrast, a constructive coping strategy such as positive self-instruction could reduce the risk of a stroke, which goes along with normal HDL cholesterol.

Lateralized cognitive visuospatial processing: is it primarily gender-related or due to quality of performance? A HMPAO-SPECT study.

The brain activity of 13 right-handed students (6 men and 7 women) was determined using high resolution (99m)Tc-HMPAO brain SPECT images during visuospatial tasks. The results showed that there was no significant gender-specific difference in solving the visuospatial tasks and that no meaningful statistical difference in brain activity between the two sexes could be found. When the sample was split into groups of good and poor performers, the results showed that there was a relatively symmetrical brain activity both frontal and parietal in subjects with poor test results. The results for those who performed the tests well, on the other hand, showed increased left frontal and right parietal brain activity. These results would suggest an asymmetric type of processing for better visuospatial brain performance independent of gender.

[Autonomic reflexes, EEG and partial arousal reaction in the near-threshold region to acoustic stimuli in the newborn]. / Vegetative Reflexe, EEG und partielle Arousalreaktion im schwellennahen Bereich auf akustische Reize bei Neugeborenen.

A sample of 19 neonates were exposed to sub- and suprathreshold acoustic stimuli. The experiment was performed with sleeping subjects. Stimuli, tones of 125, 250, 500 and 750 cps, third sounds of the same middle frequency and white noise, were applied only, if periods with no REM activity occurred. Stimulus intensity was varied from the subthreshold level (70-80 dB) to the suprathreshold level (80-100 dB). Polygraphic variables were recorded (EEG, EOG, instantaneous heart rate, respiration movements, actogram, motoric reactions and psychogalvanic reflex). The results showed, that with increasing stimulus intensity irregularities of respiratory parameters occurred. With further increase of stimulus intensity systematic changes in respiratory parameters and heart rate occurred. In addition to these changes, EEG activity and motoric reactions were obtained, when stimulus intensity reached a critical level. These data are consistent with the idea that at low stimulus intensities irregular vegetative reactions occur whereas systematic responses can be observed only, if stimulus intensity is above threshold. We conclude that with increasing stimulus intensity subcortical activity decreases whereas cortical activation increases.

Multimodal event-related potential P3 after transient global amnesia.

The putative generators of the event-related P3 component are still a matter of debate. There is reasonable evidence that the mesial temporal lobe structures are crucial in the generation of event-related potentials. Transient global amnesia (TGA) is characterized by anterograde and retrograde amnesia without neurological deficits in which a temporal hypoperfusion is the most likely pathomechanism. The aim of this study is to evaluate a possible delay in the P3 latency in a cohort of patients with TGA (n = 18). We used classic oddball paradigms with visual and auditory stimuli. The P3 latencies were compared to 18 age-matched patients with transient ischaemic attacks (TIAs) in the carotid artery territory and 23 age-matched controls. The mean age of the patients was 60.1 years (SD 14.1), in the TIA group 64.7 (SD 12.1) and 57.7 (SD 10.1) in the controls; the mean time interval between onset of TGA symptoms and performance of P3 investigations was 4.3 days (range 1-7 days); and the mean latencies measured at the vertex (Cz electrode) were 422.9 ms (SD 44.6) for the TGA patients, 436.4 ms (SD 62.1) for the TIA group, and 409.3 ms (SD 48.5) for the controls in the visual paradigm and 371.7 ms (SD 41.7), 399.7 ms (SD 51.2) and 385.3 ms (SD 46.5) in the auditory paradigm for the TGA, the TIA and the control groups. The P-values were not significant. These results suggest different neuronal networks in the generation of scalp P3 from those responsible for the disturbance of episodic memory in TGA.