Don Simms has worked tirelessly for the past two years to find a way of helping his stricken son, scouring the medical literature, buttonholing doctors and haranguing lawyers.

The medical establishment didn't like it when his efforts finally paid off last January and his son Jonathan became the first person in the world with variant-CJD to receive an experimental drug injected directly into his brain.

The move was criticised by experts who said it involved unjustified risks. More work should have been done on animals first, they said.

But people afflicted by variant-CJD cannot wait for new research. Of the 140 probable cases recorded in Britain up to last month, 136 have died. Just four are still alive, of whom Jonathan is one.

The experts feared the drug pentosan polysulphate might trigger a hypersensitivity reaction or bleeding in the brain, increasing Jonathan's suffering. Neither has happened and today, eight months on, his condition appears stabilised. The doom-mongers have been proved wrong.

But while applauding Mr Simms' determination to do everything possible for his son, the case raises difficult ethical issues. Jonathan remains a bed-bound invalid. Is the treatment merely prolonging his suffering, without adding to the quality of his life?

Last December, in the High Court, Dame Elizabeth Butler-Sloss dismissed the advice of two medical committees which warned that the treatment was unproven and risky. The Committee on Safety of Medicines said there was "no rational basis" for prescribing the drug and the CJD Therapy Advisory Committee said there was "insufficient data" on its effect and safety.

However, the CJD Therapy Advisory Committee acknowledged that "health care professionals may be more risk-averse than patients or their families when considering potential treatments for incurable diseases such as CJD."

In her judgment, Dame Elizabeth said that where there was no alternative treatment and the disease was progressive and fatal, "it seems to me to be reasonable to consider experimental treatment with unknown benefits and risks."

But there will always be the danger that patients and their families, desperate to do something, will try any unproven treatment that ends only in fostering false hope and increasing their suffering.

Mr Simms' gamble on behalf of his son, backed by his doctors, may be the first step towards finding a treatment. But only by holding a properly controlled trial can doctors learn the real lessons that might bring benefits to future patients.