SUMMARYThis paper describes an investigation into the relationship between senile dementia and slowing of peripheral nerve conduction velocity. Twenty-eight demented patients and 19 controls were studied. Each patient was rated clinically and given a battery of simple psychological tests in addition to the physiological recordings. The results were as follows: (1) Motor nerve conduction was slower in the demented group than in the control group but this difference was not significant. (2) When subjects were divided according to their dementia score, those with scores above 7 were found to have motor nerve conductions which were significantly slower than those with scores of 7 or less. (3) There was a significant correlation between the severity of the dementia as measured by the rating scale and the psychological tests and the degree of slowing of motor nerve conduction. (4) In those patients who were retested after one year, increase in dementia was significantly correlated with a further slowing of conduction in motor nerves. (5) The possible role of vitamin deficiency was investigated in a small sub-group of demented patients. Deficiencies of thiamine, nicotinic acid, and vitamin B12were not thought to be important but some patients had low folate levels. The significance of these results is discussed.

SYNOPSISSpecific cortical somatosensory evoked responses were recorded in nine patients suffering from senile dementia and eight elderly depressed patients. The results were as follows. (1) The latencies of each peak were longer in the demented than in the depressed group but this difference was significant only for peak 3 (the second negative deviation). (2) The late negative deviation (peak 5) was either absent or very flat in demented patients. The ratio of the amplitude of this late wave to that of the first peak discriminated between demented and non-demented patients at the 0·5% level. (3) The value of this ratio combined with that of the latency of peak 3 could be used to classify all but one patient into the correct diagnostic group. The results are discussed in the light of the relevant literature. It is suggested that slowing of conduction in the nervous system may be a very basic disturbance associated with cognitive impairment in old age and that measurements of this kind may come to assist in the diagnosis of dementia.