WordNet sense 1 (a symptom of reduced quality or strength):

deterioration

WordNet sense 2 (the condition of being unable to perform as a consequence of physical or mental unfitness):

disability, disablement, handicap

WordNet sense 3 (the occurrence of a change for the worse):

damage, harm

WordNet sense 4 (the act of making something futile and useless (as by routine)):

constipation, stultification, deadening