Prednisone should be given with precaution in people who suffer from depression or mental disorders.
Mood disturbances are occasionally seen in patients treated with corticosteroids.
This usually happens when higher doses are given, like in pulmonary conditions.
Patients may present with delirium or a schizophreniform psychosis, but mood disorder, including manic, depressed, and mixed episodes, are far more common.
What was your father given for treatment of prednisone-induced mania?