In the first clinical trial of gene therapy for Alzheimer's disease researchers have produced preliminary evidence that gene therapy may slow the decline in mental functioning associated with Alzheimer's disease.
The gene therapy was used on eight patients with early-stage Alzheimer's and it was found that six successfully received the gene transfer and had a slower rate of cognitive decline in the 22 months after treatment than in the 14 months before, as measured by a standardized test.
Gene therapy has been tried for 15 years for a variety of diseases, with little success and in many cases, hints of efficacy in early trials like this one were not confirmed in larger studies where treatment was compared with a placebo.
The gene involved in this trial controls production of nerve growth factor, a protein that can protect brain cells from death. Previous attempts to use the growth factor itself as a drug have had severe side effects.
In the trial the first two patients, sedated but awake, moved their heads during the surgery and suffered brain haemorrhages, with one of them eventually dying. In the next six operations general anaesthesia was used and they were successful.
Dr. Tuszynski and colleagues from University of California, San Diego thought that it might be better to use the gene to induce cells in the brain to produce their own growth factor just where it was needed. They took skin cells from each patient's back and, in the laboratory, used a virus to carry the gene into the cells. The cells, which began producing the growth factor, were then injected into the brain.
A paper on the trial was published online yesterday in Nature Medicine.