Home secretary Jack Straw has angered civil liberty campaigners with his insistence on preventive detention for people with a severe anti- social personality disorder, while leaving those involved in delivering mental health services bemused by his lack of detail (news focus, 25 February).

Many of our members and service users receive a diagnosis of personality disorder which later proves incorrect, particularly young people with first-onset mental illness, people with co-morbid substance abuse, and those from black and ethnic minorities. Left untreated, or treated badly, schizophrenia can look very like personality disorder to mental health professionals. The average delay between onset of schizophrenia and the first treatment is currently 18 months.

Personality disorder is a catch-all diagnosis, including conditions that can in no way be considered dangerous to others. Someone with obsessive compulsive disorder who feels compelled to wash many times a day is not a risk to the public. A small number of people are so dangerous that preventive detention is justified, but let the criterion for this be assessment of dangerousness, not of diagnosis. Any legislation on personality disorder should be kept separate from the new mental health act. The two measures must be compatible and leave no gaps, but the issues are different.

Cliff Prior

Chief executive

National Schizophrenia Fellowship

Kingston upon Thames