US researchers have announced that inserting genetically modified tissue directly into the brain will significantly alleviate the symptoms of Alzheimer's disease. In experimental surgeries that took place in 2001 and 2002, the genetically modified tissue was implanted deep within the brains of the eight patients who had volunteered for the study. Doctors say the study shows gene therapy may significantly slow down Alzheimer's. In fact, the brain tissue of one patient showed new growth. Of the six patients who completed the procedure safely. The Mini Mental Status Examination,which evaluates cognitive function, was administered during a follow-up assesment period of approximately 22 months. The tests showed the rate of cognitive function decline of the patients was reduced by 36 to 51 percent. Researchers examined the brain tissue of a study participant who had died and found robust nerve growth near the site of procedure. Cholinergic neuron loss is a cardinal feature of Alzheimer's disease. Experts warn however that the study was designed to test the technique's safety, not its efficacy. While promising, signs of impreovement may not be reliable.