Reflex elicitation thresholds in senile dementia.
Forty-eight female patients with the diagnosis of senile dementia and 20 elderly healthy women were studied concerning thresholds for orienting responses to intermittent light, the eyelid reflex, and hand withdrawal on electrical pain stimulation. A U-shaped relationship between degree of mental deterioration and reflex thresholds was predicted from two assumptions: (1) that reflex thresholds are progressively increased following the general blunting of cognitive processes, and (2) that active inhibition of certain overt behaviour takes place in patients with little deterioration (as well as in healthy people). The U-shaped relationship was only obtained for the eyelid reflex, and support was only obtained in connection with the orienting response for the assumption that some active inhibition of overt behaviour normally takes place. A further hypothesis was that thresholds for protective-defensive reflexes would not be substantially increased in the most deteriorated cases. This expectation was confirmed only for the hand withdrawal reflex. It is concluded that for the orienting response and for the eyelid reflex there is some relation, although the form is unclear and a rationale is lacking, between the thresholds and degree of mental deterioration. It is further concluded that the threshold for the hand withdrawal reflex is unrelated to the degree of mental deterioration. The inertia of the senile demented patients is stressed as well as their undifferentiated reactions. It is suggested that cognitive defects may partly explain these deficiencies.
D000368:Aged; D003704:Dementia / Q000503:physiopathology*; D004553:Electric Conductivity; D004558:Electric Stimulation; D005143:Eyelids; D005260:Female; D006225:Hand; D006801:Humans; D010775:Photic Stimulation; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time; D012018:Reflex; D012867:Skin