A method of treating patients suffering from Alzheimer's disease by locating the areas of the brain affected by Alzheimer's disease and acting on the aforementioned areas of the patient's brain by laser energy through coronary blood vessels located adjacent to the aforementioned areas. The laser energy is delivered to the affected area through a set of microcatheters insertable sequentially and coaxially into each other and having diameters that allow insertion into distal coronary blood vessels.