THEATRE / The powerlessness of mind over matter: Paul Taylor reviews Peter Brook's production of The Man Who . . . at the Contact Theatre, Manchester

A former US president used to be the butt of a cheap gag that claimed he couldn't walk and chew gum at the same time. Since this was meant to reflect on his IQ rather than on his brain condition, the Gerald Ford Syndrome is not one that is recognised by neurology. But, suppose that you were highly intelligent and yet could not walk and hold a cup at the same time, having lost all ability to move except by staring fixedly at the part of the body you wished to shift. Suppose, too, that there was no guarantee from one day to the next that you would be able to achieve even this, so that nothing remained as a habit, but had to be daily relearned as tricks and stratagems in a humiliating and exhausting mental marathon.

This is one of the cases brought, powerfully and respectfully, to our attention in the new Peter Brook production The Man Who . . . which is based on Oliver Sacks' Eighties bestseller The Man who Mistook his Wife for a Hat. The case-study in the title (of a doctor of music who developed visual agnosia and couldn't recognise everyday objects) has already inspired a chamber-opera by Michael Nyman which self- reflexively fixes on the fact that, as Dr P's world disintegrated around him, music became his life-line, erstwhile automatic activities like dressing and washing having to be negotiated now along the track of a song.

The piece that Brook and his team have fashioned ranges more widely through those neurological disorders which, in removing something we take for granted, give us a new, defamiliarising access into the mysteries of what it is to be a person. And, though it's a true work of art, The Man Who . . . is not as concerned as the opera to convert its subject into an artwork. One way of defining its humane excellence is to ask what advantages it has over, say, a television documentary that filmed the actual sufferers in their home and hospital environments.

Purity of focus and a refusal to exploit the 'freak show' aspects would be high on the list. Played on a blond wooden square with just a few white chairs, a video camera and a couple of monitors, the piece rinses its material clean of all redundancy. The multi-ethnic male cast of four, continually exchanging white coats for pyjama tops, play people on both sides of the chasm which has the effect of dampening the them / us reflex.' People don't want to know us, but we're in fashion,' complains the eruptive, tic-ridden sufferer from Tourette's Syndrome, causing you to feel a salutory twinge of shame.

With a chaste, mostly percussive accompaniment from a lone musician at the side, the piece combines playfulness and sadness, alive to the fact that these conditions are both funny and no joke. The tact with which it handles people who have lost all right- field vision and only shave one side of their face, or who think that they have their mother's arm in bed with them, is too understated to be described as 'exquisite'. It is a thing of beauty none the less.

Particularly painful are the moments when those sufferers who are, by definition, oblivious to their condition are made aware of it through technological means, like video feedback. A man listens to the recording of himself reading Gray's Elegy and, recognising it as gobbledigook, breaks down in tears, tries to affect appreciativeness for his rendition, fails and breaks down again. In its sincerity and its restraint, The Man Who . . . is the triumphant antithesis to the Oprah Winfrey approach to human suffering.

'The Man Who . . .' continues at the Contact Theatre until 26 March (061-274 4422); then tours to the Newcastle Playhouse (29 March-9 April), Glasgow Tramway (12-23 April), Nottingham Playhouse (26- 30 April) and London, National Theatre (4-21 May)