The author sums up the views and results of the research into the diag
nostics of deterioration and assessment of the pre-morbid state by Wec
hsler's tests. On the basis of 25 studies, he states the unreliability
of Wechsler's index of deterioration, of vocabulary scatter and compa
rison of verbal IQ and performance IQ. He points out new trends, such
as diagnostics of intellect deterioration and assessment of pre-morbid
level on the basis of other types of vocabulary tests in the Anglo-Sa
xon area, and using demographic coefficients for finding out the pre-m
orbid level. In spite of several decades of criticism, Wechsler's appr
oaches are used by many clinical psychologists. The author points out
the importance of clinical analysis of patient's intellectual performa
nces and their comparison with the assumed pre-morbid performance. The
importance of clinical analysis is - with regard to the low validity
of Wechsler's constructions - higher than it is sometimes expected.