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Your report that researchers at the University of Aberdeen have discovered how electroconvulsive therapy (ECT) actually works to relieve severe psychological depression is to be welcomed ("Shock result", Campus round-up, 29 March).

However, the claim that ECT "is 75 to 85 per cent effective" must be regarded with caution, as the follow-up time after final treatments is not specified and it is known that beneficial effects tend to wear off after several months.

Also, Information on ECT, a leaflet published by the Royal College of Psychiatrists, points out that a UK review of a number of studies in 2003 found that the proportion of people who had had ECT and found it helpful ranged from 30 per cent to more than 80 per cent. It is also important to note that in user- and doctor-led studies, between 30 per cent and 50 per cent of patients complained of memory loss.

R.E. Rawles, UCL honorary research fellow in psychology, University College London