18 months after successful treatment

RT can have side effects especially tiredness but your partner should be long over these by now. However, it is common for men to have HT for anything up to 3 years unless they have need of continuing HT due to their advanced staging. Also, it does take time to overcome the effects of HT after it has stopped and generally the longer on HT, the longer the effects last. Apart from the physical side effects such as premature fatigue, aching joints, hot flushes etc., HT can cause a marked change in the personality of some men and partners of some men say he is like a different person. I wouldn't say HT would make him struggle for words which seems to me to be more like the onset of a form of Dementia such as Alzheimers (which sadly my wife has). In any event, he needs to see his GP to arrange for an assessment without delay.