Sir

Your News story “Doctors seek lost data on Alzheimer's vaccine” (Nature 430, 715; 200410.1038/430715a) correctly points out that Elan's approach to treating Alzheimer's disease is “one of the few potentially viable options for controlling the disease”. However, we would like to correct an inaccurate statement regarding the results of the discontinued AN-1792 trial.

Research carried out by Nick Fox of the Institute of Neurology in London, presented at the International Conference on Alzheimer's Disease and Related Disorders in July, measured the brain volume of patients enrolled in Elan's clinical trial of AN-1792. Fox found that the brain volume of patients treated with AN-1792 who responded to the treatment by making antibodies diminished by 3% — not the 6% stated in your News story — and this decrease was only 1% greater than the brain-volume reduction in those who were treated with a placebo.

In addition, Fox commented that, although the brain-volume reduction was unexpected (not “alarming”, as the News story suggests), the small changes seen might be due to the removal of plaque lesions in the brain tissue of patients suffering from Alzheimer's.

We continue to pursue a number of immunotherapy approaches to Alzheimer's disease, including several in preclinical phases of development, with the goal of bringing a meaningful treatment to the millions of individuals, families and caregivers affected by this devastating disease.