Six patients are showing signs that their genetically modified tissue implants have been successful in slowing their Alzheimers. Between 2001 and 2002, the patients participated in a gene therapy experiment at San Diego's University of California. The tissue used in the experiment was designed to boost a naturally occurring protein that stops cell death and stimulates cell function. Professor Mark Tuszynski, the neurologist who led the research, said their latest follow up of these six patients suggested the treatment was working. Memory tests suggest the gene therapy has slowed cognitive decline by as much as 50%. brain scans also show that the patients' brains are more active than before. All studies conducted thus far have been to check that the technique is safe. Having safely taken the technique from animal to human use the researchers are now free to continue the study. Now that has been shown, further studies can be done to determine how effective the treatment is. Harriet Millward, deputy chief executive of the Alzheimer's Research Trust, said the research was very exciting, but cautioned that it would not be a complete cure for Alzheimer's.