The present invention provides a combined therapy comprising the use of one or more omega-3 fatty acids and one or more B vitamins and for treating cognitive impairment, such cognitive impairment disorders include, especially but not exclusively, Mild Cognitive Impairment (MCI) and Alzheimers disease (AD). The present invention also provides a treatment: for individuals suffering from cognitive impairment disorders that occur as a result of brain or cerebral atrophy, the invention includes inter alma methods of treating and/or reducing progression of brain atrophy and pharmaceutical compositions and nutritional supplements therefor.