The Former Governor of Mountjoy Jail John Lonergan has said prison is "a disaster" as a response to people with mental health problems.
The National Mental Healthcare Conference is taking place today in Dublin and Mr Lonergan will deliver an address on the effects of prison on people with personality disorders.
Mr Lonergan spent 26 years as Governor of the jail and said he witnessed the devastating consequences of deprivation, where the lack of early intervention for young people led to difficulties with the law and time spent in prison.
Mr Lonergan said he is "adamant" prison is not the answer for people with mental health issues.