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CNV rebound and Alzheimer's disease
$46 W 9.05 COGNITIVE I M P A I R M E N T S A N D AUDITORY EVENT-RELATED POTENTIALS IN PATIENTS WITH ALZHEIMER'S DEMENTIA A N D KORSAKOFF'S SYNDROME.
W 9.07 VISUAL EVOKED POTENTIALS IN NORMAL AGEING A N D DEMENTIA.
D.H.R. Blackwood, I.M. Blackburn, D.M. St. Clair, J. Tyrer and J.E. Christie
(Birmingham, UK)
(Edinburgh, UK) The purpose of this study is to examine the relation between auditory event-related potentials and cognitive changes in patients with two types of dementia. 20 patients admitted to a psychiatric ward for investigation of presenile dementia were clinically diagnosed as suffering from Alzheimer's disease after detailed investigations had excluded other causes of dementia. 18 patients with Korsakofrs syndrome were hospital in-patients and their selection was based on the criteria of severe anterograde memory deficiency with a definite history of alcohol abuse. 23 age-matched control subjects had no history of psychiatric or neurological disease. Auditory event-related potentials including P3 were recorded using a two-tone discrimination task. Neuropsychological assessment was performed on all subjects using an adaptation of the Luria-Nebraska test battery. 10 patients with AIzheimer's disease and 16 patients with Korsakoff's syndrome were fully re-tested one year after their initial assessment. The relations between items in the Luria test battery and event-related potentials and in particular, the latency of P3, have been examined.
Christine E. Wright and G.F.A. Harding
Studies of the VEP across the adult life span in 70 normals show a mean flash P2 latency increase of the order of 20 msec between the 2nd and 8th decade. The latency of the pattern reversal P100 component (56' check) only increases by 6 msec. Patients with dementia show an exaggeration of this ageing process. The flash P2 component is grossly delayed while the pattern VEP is within normal limits when compared with normal controls, and patient controls with affective disorders, Over 30 patients have been studied. Current theories indicate that cholinergic defects underlie the symptoms of dementia of the Alzheimer type. We recorded flash and pattern reversal VEPs in 10 young volunteers before and after an injection of the centrally acting anticholinergic drug Hyoscine Hydrobromide (0.6 mgm S.C.). During the maximum action of the drug there is a small but significant increase in the latency of the flash P2 and N3 components. The pattern reversal VEP is unaffected by the drug. This indicates that our flash VEP results in dementia could be due to a reduction in cholinergic activity. It appears that the flash and pattern VEP reflect different aspects of cortical processing.
W 9.08 CNV R E B O U N D AND ALZHEIMER'S DISEASE. W 9.06 C O M P A R I S O N OF D I A G N O S T I C YIELD OF EEG AND P3 IN PATIENTS WITH DEMENTIA.
J.J. Tecce, L. Cattanach, R.J. Branconnier and J.O. Cole (Boston, MA, USA)
M.J. Aminoff and D.S. Goodin (San Francisco, CA, USA) The P3 (P300) response has recently been studied in demented patients and found to be of prolonged latency in most instances. Its yield relative to conventional EEG has not, however, been examined. We therefore studied 32 patients with clinically definite dementia of the Alzheimer type in order to compare the utility of these two techniques in the evaluation of these patients. The EEG was normal in 14, abnormal in 12, and equivocal in 6 (because of mild slowing or a slow alpha rhythm of uncertain significance). The P3 response was normal in 4, abnormal in 18, and equivocal in 10 (because of poor reproducibility or absent responses). No patient with equivocal or abnormal EEG findings had a normal P3 response, although 4 with abnormal EEGs had equivocal P3 responses. By contrast, in 10 patients with abnormal P3 responses, the EEG was normal or equivocal. In 10 patients neither test was definitely abnormal. We conclude that the P3 response is more sensitive than conventional EEG in evaluating patients with dementia, but that both techniques complement each other.
The two purposes of the present study were to evaluate eventrelated brain activity (CNV rebound) as a possible diagnostic indicator of Alzheimer's disease and to provide preliminary information on pharmacotherapy. Fourteen Alzheimer's patients (ages 57 to 89 years) were compared to three non-patient control groups: 35 young subjects (ages 18 to 32), 38 aging individuals (ages 55 to 69 years), and 23 elderly individuals (ages 70 to 85 years). Two CNV paradigms were used (1) a control condition, where a light flash (first stimulus or S1) was followed by a continuous tone (second stimulus or $2), which was terminated by a key press: and (2) a divided attention condition, which was identical to the control task, except that three letters were also presented in the S1-$2 interval as a short-term memory task. The unexpected omission of letters produced a supranormal elevation of CNV magnitude at Fz, Cz, and Pz in normal young subjects. This CNV rebound effect was diminished in normal elderly groups and was absent in Alzheimer's patients. Pharmacotherapy with Hydergine restored CNV rebound in a subgroup of patients. CNV rebound appears to be a potentially useful neurophysiological indicator of brain pathophysiology and efficacy of pharmacotherapy m senile dementia.
W 9.07 VISUAL EVOKED POTENTIALS IN NORMAL AGEING A N D DEMENTIA.
D.H.R. Blackwood, I.M. Blackburn, D.M. St. Clair, J. Tyrer and J.E. Christie
(Birmingham, UK)
(Edinburgh, UK) The purpose of this study is to examine the relation between auditory event-related potentials and cognitive changes in patients with two types of dementia. 20 patients admitted to a psychiatric ward for investigation of presenile dementia were clinically diagnosed as suffering from Alzheimer's disease after detailed investigations had excluded other causes of dementia. 18 patients with Korsakofrs syndrome were hospital in-patients and their selection was based on the criteria of severe anterograde memory deficiency with a definite history of alcohol abuse. 23 age-matched control subjects had no history of psychiatric or neurological disease. Auditory event-related potentials including P3 were recorded using a two-tone discrimination task. Neuropsychological assessment was performed on all subjects using an adaptation of the Luria-Nebraska test battery. 10 patients with AIzheimer's disease and 16 patients with Korsakoff's syndrome were fully re-tested one year after their initial assessment. The relations between items in the Luria test battery and event-related potentials and in particular, the latency of P3, have been examined.
Christine E. Wright and G.F.A. Harding
Studies of the VEP across the adult life span in 70 normals show a mean flash P2 latency increase of the order of 20 msec between the 2nd and 8th decade. The latency of the pattern reversal P100 component (56' check) only increases by 6 msec. Patients with dementia show an exaggeration of this ageing process. The flash P2 component is grossly delayed while the pattern VEP is within normal limits when compared with normal controls, and patient controls with affective disorders, Over 30 patients have been studied. Current theories indicate that cholinergic defects underlie the symptoms of dementia of the Alzheimer type. We recorded flash and pattern reversal VEPs in 10 young volunteers before and after an injection of the centrally acting anticholinergic drug Hyoscine Hydrobromide (0.6 mgm S.C.). During the maximum action of the drug there is a small but significant increase in the latency of the flash P2 and N3 components. The pattern reversal VEP is unaffected by the drug. This indicates that our flash VEP results in dementia could be due to a reduction in cholinergic activity. It appears that the flash and pattern VEP reflect different aspects of cortical processing.
W 9.08 CNV R E B O U N D AND ALZHEIMER'S DISEASE. W 9.06 C O M P A R I S O N OF D I A G N O S T I C YIELD OF EEG AND P3 IN PATIENTS WITH DEMENTIA.
J.J. Tecce, L. Cattanach, R.J. Branconnier and J.O. Cole (Boston, MA, USA)
M.J. Aminoff and D.S. Goodin (San Francisco, CA, USA) The P3 (P300) response has recently been studied in demented patients and found to be of prolonged latency in most instances. Its yield relative to conventional EEG has not, however, been examined. We therefore studied 32 patients with clinically definite dementia of the Alzheimer type in order to compare the utility of these two techniques in the evaluation of these patients. The EEG was normal in 14, abnormal in 12, and equivocal in 6 (because of mild slowing or a slow alpha rhythm of uncertain significance). The P3 response was normal in 4, abnormal in 18, and equivocal in 10 (because of poor reproducibility or absent responses). No patient with equivocal or abnormal EEG findings had a normal P3 response, although 4 with abnormal EEGs had equivocal P3 responses. By contrast, in 10 patients with abnormal P3 responses, the EEG was normal or equivocal. In 10 patients neither test was definitely abnormal. We conclude that the P3 response is more sensitive than conventional EEG in evaluating patients with dementia, but that both techniques complement each other.
The two purposes of the present study were to evaluate eventrelated brain activity (CNV rebound) as a possible diagnostic indicator of Alzheimer's disease and to provide preliminary information on pharmacotherapy. Fourteen Alzheimer's patients (ages 57 to 89 years) were compared to three non-patient control groups: 35 young subjects (ages 18 to 32), 38 aging individuals (ages 55 to 69 years), and 23 elderly individuals (ages 70 to 85 years). Two CNV paradigms were used (1) a control condition, where a light flash (first stimulus or S1) was followed by a continuous tone (second stimulus or $2), which was terminated by a key press: and (2) a divided attention condition, which was identical to the control task, except that three letters were also presented in the S1-$2 interval as a short-term memory task. The unexpected omission of letters produced a supranormal elevation of CNV magnitude at Fz, Cz, and Pz in normal young subjects. This CNV rebound effect was diminished in normal elderly groups and was absent in Alzheimer's patients. Pharmacotherapy with Hydergine restored CNV rebound in a subgroup of patients. CNV rebound appears to be a potentially useful neurophysiological indicator of brain pathophysiology and efficacy of pharmacotherapy m senile dementia.