Sentence:  He showed convincingly that <WSD>anxiety</WSD> is a learned ( conditioned ) reaction and is the basis of experimental and clinical neuroses and assumed , therefore , that the neuronal changes which underlie the neuroses are functional and reversible . 
Meaning of the word marked with <WSD> tags:  (psychiatry) a relatively permanent state of worry and nervousness occurring in a variety of mental disorders, usually accompanied by compulsive behavior or attacks of panic