Hi, Cheshire Archives are your best option for information. There are registers of entry to the Asylum which survive, I found some limited information concerning a great aunt in them. Just to say that there is a 100 year rule on disclosure of information on some records. It’s of note that your relative was very young to have suffered from this condition. I do wonder if this diagnosis was just ‘tacked on’ to his death certificate as in those days a more refined diagnosis may not have been available. Cheshire Archive staff are very helpful. Good Luck.