Sentence:  Thirteen patients improved one point or more (improvers), 18 patients worsened in psychosis one point or more (<WSD>worseners</WSD>) and 14 did not change (nonchangers). Patients who improved were able to focus better on the interview, were less hindered by delusions, hallucinated less, were more trusting and were less anxious. d-Amphetamine blood levels were identical for improvers and <WSD>worseners</WSD>. The preinfusion psychosis ratings were significantly different among the three groups: [...] 
Meaning of the word marked with <WSD> tags:  One who or that which worsens (internally), becomes worse, deteriorates in condition.