Some aspects of the invention provide for a method of treating Alzheimer's Disease, Mild Cognitive Impairment, Frontotemperal Dementia, Amyotrophic Lateral Sclerosis and/or Multiple Sclerosis using polyunsaturated fatty acids which are modified in certain positions to attenuate oxidative damage by Reactive Oxygen Species (ROS) and/or suppress the rate of formation of reactive products and toxic compounds.