An innovative new computer program called Beating the Blues claims to be able to help patients suffering from depression and anxiety. But can a machine really be a replacement for face-to-face treatment? Steve Boggan investigates

Douglas Adams will be laughing in his grave and Arthur C Clarke could be forgiven for saying "I told you so," but at the Priory Clinic they're deadly serious: they have installed a computer to treat patients for depression and anxiety. Not since Marvin, Adams's depressed robot in The Hitchhiker's Guide to the Galaxy, and Clarke's HAL, the paranoid computer of 2001: A Space Odyssey, has science fiction seemed so crazy.

But this is science fact, and it works. The north London branch of the clinic, better known for helping the rich and famous deal with their addictions, is trialing an interactive therapy system where patients sit at a console and learn to identify and manage their problems through two-way communication with the computer.

The system, Beating the Blues, has proved so successful and so easy to use that therapists believe sufferers will eventually be able to treat themselves at home, with professionals monitoring them by e-mail. Beating the Blues was developed at the Institute of Psychiatry in London in conjunction with Ultrasis Plc, a company which makes computerised healthcare products.

It works by using established techniques of cognitive behaviour therapy (CBT). Such therapy, which boasts a success rate of upwards of 75 per cent when delivered face to face, takes sufferers through systematic steps to help them think differently about everyday situations, so that they can control the links between negative feelings, behaviour and thoughts.

For the first of eight one-hour sessions costing a total of £400, patients meet a real therapist and are told about the programme and how to use it. They always have access to professional help if they need it, but after the first session the treatment involves patients watching short films on the progress of five real case studies played by actors, answering set questions posed by the computer and writing down how they feel about situations.

The interaction with the computer, coupled with print-outs of set "homework" designed to break the downward spiral of depression, effectively helps the patients to help themselves by identifying their problems, the symptoms they lead to and by offering advice on dealing with the issues raised. At the start of each session, the computer is programmed to ask the patient to assess how depressed or anxious they are feeling on a scale of one to eight.

If their condition seems to be cause for concern, the computer alerts a clinician. Because CBT does not seek to root out problems from the past, only dealing with current situations, this is the only time that a therapist need be recalled. In controlled trials conducted by the Institute of Psychiatry, formal details of which are expected to be published soon, psychologists found that the computer therapy compared favourably with face-to-face treatment.

Given that the waiting list for face-to-face treatment on the NHS is currently up to 18 months, the hope is that computers will help slash waiting times in the future. "In the past, people found it difficult to use computers, but you could argue now that they feel more comfortable with a computer than with a therapist," said Rob Wilson, the Priory's CBT co-ordinator.

"They feel they can tell a computer things they wouldn't tell another person, and that helps. The information remains private, even from us, because all it does is help lead on to another step. It is very systematic and very effective." Dr Judy Proudfoot, a psychologist at the Institute of Psychiatry, developed the system, even getting involved in filming the five case studies so that they would be as realistic as possible.

As the treatment progresses, the computer shows users how the case studies – an elderly woman, a harassed schoolteacher, a man who loses his job, a mother suffering anxiety attacks after a car crash and a depressed and broke single mother – are coping with their own therapy.

"Patients came to identify with all or part of the case studies and learned to empathise with the subjects – simply knowing you're not the only one who feels like you do is a help," Dr Proudfoot said.

"We have conducted controlled trials among 160 patients and we are very excited indeed by the results. People feel very comfortable sharing their problems with a computer. At the moment, the only thing stopping this being communicated to a patient's home computer is the bandwidth needed for us to send down the case-study films. But as communication gets faster, people could have one session with a therapist, then the others at home, with a clinician keeping an eye on things by secure e-mail."

If only the system had existed in Douglas Adams's day, he could have offered us the delicious prospect of a robot receiving therapy from a computer.