When I was 14 or so, I became aware that something was very wrong with a teenage cousin of mine. Although never let in fully on the secret, I picked up enough from my parents' muttered asides and whispers to know that the problem was far more interesting than a mere physical illness: my cousin had been hearing voices and had become extremely distressed and paranoid. He'd found personal and dreadful messages for him in the Bible and was clearly and typically, as I later discovered, in the throes of schizophrenia.

He was lucky: he had a close and medically aware family and quickly got the help he urgently needed, but had this not been the case there would have been nowhere for him and his parents to turn to for help and advice. Mental illness is hard to deal with at the best of times. Without knowledge of exactly what it means and what can be done to help, the fear and secrecy that are so often involved can cause it to fester and grow.

Like many others, I was first inspired to take an interest in schizophrenia by Marjorie Wallace's extraordinary newspaper articles that appeared 16 years ago. They didn't just touch me – they stirred some distant memories of my cousin that had been lying dormant since my childhood.

Marjorie's compassionate and compelling words brought back memories of seeing my cousin lonely and terrified, and I was delighted when she asked for my help in setting up SANE in 1986. I was amazed to learn from her just how little support there was for this widespread and devastating illness, and, as we sat in my kitchen together and rang round everyone we knew to try to interest them in mental illness, it became clear that this was a cause for which it would not be easy to find support.

But we pressed on and managed to find enough willing friends to form Stars for SANE as we called it then, a group of people who joined together to help to raise funds for SANE and SANELINE. Over the years, we've organised the kind of occasion that every charity needs in order to raise money and awareness – from a ball held at the Royal Lancaster Hotel attended by the Prince and Princess of Wales, to a Midsummer Night's banquet at St James's Palace and a dinner at Highgrove. But despite all these events and the hard work it took from those involved, it's been a continuing struggle to find enough funds to keep the helpline going, especially as it needed to grow rapidly to meet the demand.

Where SANELINE is so invaluable is in not only providing someone to talk to who understands and can offer encouragement, but also in giving the kind of practical information that is needed. This includes local contacts that offer help such as carers and discussion groups, information on treatments, and details on mental health laws and rights as patients and carers. SANELINE's Caller Care service means that people can be called back when it is known that they might need extra support or are going through a difficult time.

I find it extremely painful to imagine a young person in the throes of deep unhappiness, panic and confusion who has no one to whom he can turn, or to think of distraught families who have no way of coping with a child who has become unrecognisable.

I have enormous faith in the compassion and generosity of the British people, and I'm sure it's only because of lack of understanding that mental illness is still a cause that finds little support. I appeal to all readers of The Independent on Sunday to support the IoS SANE Christmas appeal. No one should have to live in fear: if you can afford to give this Christmas you will be helping to relieve the suffering of those in deep distress.