Why Alzheimer's drug hopes may be misplaced

The enthusiasm generated by an IVIg trial that involved a handful of people may be down to a shortage of other avenues 

guardian.co.uk, Sarah Boseley, health editor, Wednesday 18 July 2012

The IVIg results have been promising – but the number of people involved is
too small for the results to be reliable. Photograph: Seth Wenig/AP

A pill to prevent Alzheimer's disease would be a wonderful discovery and net a fortune for the manufacturer (in this case, Baxter). But we're a very long way from it yet. The enthusiastic reaction from some quarters to a tiny trial reported at the Alzheimer's Association international conference in Canada is as much to do with the distressing shortage of effective treatments for the disease as the actual results.

The researchers from Weill Cornell University in New York reported on a one year follow-up period to their original two-year trial, the results of which have already been published. The original trial involved just 24 people. Sixteen people completed the full three years, only 11 of whom were originally given intravenous immunoglobulin (IVIg), a blood product containing antibodies from over 1,000 blood donors which is mostly used in diseases involving a problem with the body's own immune system.

The volunteers were all in the early stages of younger-onset genetic Alzheimer's. This is a rare group comprising 2% of the global Alzheimer's-suffering population. Disappointing results of trials in all sorts of therapies with Alzheimer's patients have led scientists to think they may be treating people too late in the day, when damage to the brain has already occurred.

The results have been promising – but the number of people involved is too small for the results to be reliable. There may be particular reasons why this handful of patients did well. And in the third year, not only the original 11 but also all the rest of the people in the study were given IVIg. That means there was no control arm to measure progress against.

The researchers say they now want to embark on a large phase-three study of IVIg. We will have to wait for the results of that to find out whether IVIg can really prevent Alzheimer's.