Hi. I had gone through your query. Long term Physical illness may associated psychiatric co morbidity. Depression is the commonest psychiatric illness among those patients. Methotraxate can cause mood variability and mood swings. But It is not always or difficult to separate it from natural course of psychiatric illness. Detail evaluation will give more confirmatory diagnosis. Methotraxate can cause illness that mimic psychosis. It can be treated with reduce the dose of medicines or add another medicines that control psychological illness. So consult psychiatrist for detail assessment. I hope i have answered your query. Thank you.