The TV star fist started taking drugs as a teenager, but it was when she was working in Australia as a journalist and suffering from clinical depression that her drug use spiralled out of control.
Speaking to The Sunday People, the 56-year-old said: “My life was in absolute chaos and things such as paying the bills and even cleaning my house were no longer important to me.
“But I didn’t care because I loved the mellow feeling that enveloped me when I smoked weed. And being stoned a lot helped me to block out the negative feelings that I felt about my life.
“If you live with depression, you do a certain amount of self-medication and smoking dope became my coping mechanism.”
Later on, Trisha experimented with ecstasy.
“I was never tempted to try coke or speed because I am hyper enough and I needed something to make me feel happy.
“Taking ecstasy made me feel loved up and it was the most incredible feeling. But it also brought on the most incredible lows and it made me feel suicidal at times. The downs in the middle of the week were awful and my terrible mood swings affected everything.
“It was my therapist who finally told me to stop taking it and I knew that if I didn’t I would have ended up back in the psychiatric hospital. But when I stopped taking it my depression returned with a vengeance. I was put on a course of anti-depressants for nine months.”
Trisha is now clean and has managed to stay drug-free for two decades.
“I haven’t touched an illegal drug for 20 years.
"But there’s no way I could even have a puff of a joint. It would take me back into that big black hole that I used to exist in.”