The multiple vocabulary test has been used to investigate approaches to objectifying general mental deterioration. Compared to methods used to determine the actual level of intelligence, the premorbid levels of intelligence which were determined with the use of the multiple vocabulary test were roughly the same for patients with brain injuries that cannot be detected by means of specialized instruments. In the case of patients where brain injuries were detectable through the use of instruments, the premorbid level of intelligence was significantly higher than the actual intelligence level. Patients with general mental deterioration showed highly significant differences between premorbid and actual levels of intelligence. The results obtained indicate that the multiple vocabulary test is a useful means of diagnosing general mental deterioration due to organic or psychological factors. Also discussed by the authors in their present paper are hitherto unsolved problems that stand in the way of an objective diagnosis of dementia and loss of intelligence.