Continuous reaction times in cerebral dysfunction.

The Continuous Reaction Times (CRT) method was used to examine pharmacological, psychiatric, medical and neurological problems in clinical practice where a detailed neuropsychological examination with a test battery was not possible. Either 100 visual or 150 auditory stimuli were given within a period of 6 1/2 or 10 min respectively, and the patients were instructed to react as quickly as possible to every stimulus. The same CRT method was applied to heterogeneous groups of patients with cerebral dysfunction and control subjects. The results demonstrated that it was useful as a screening test for the presence of cerebral dysfunction and was especially sensitive to progressive diseases. Its discriminative power was equivalent to more sophisticated and complex psychological tests. Even if CRT is a valid and reliable method of testing cerebral affection, the neural background for the reaction time process is still unknown and the test did not distinguish between patients with right- or left-hemisphere lesions and was not influenced by the etiology of the disease. CRT is therefore considered a provisional method, suggestive only for the actual diagnostic procedures. Only when the patients have a well-defined diagnosis e.g. a diffuse cerebral affection caused by a drug or a metabolic disorder can CRT be recommended as a measure of the degree of lowered consciousness.