A method of stabilizing and potentiating actions and administration of neurotrophins such as brain-derived neurotrophic factor (BDNF), neurotrophin-3, neurotrophin-4, and nerve growth factor and their receptors by using in coupling conjugation with polyunsaturated fatty acids (PUFAs) in the prevention and/or treatment of obesity, type 2 diabetes mellitus, metabolic syndrome X, Alzheimer's disease, depression, Parkinson's disease, and schizophrenia is described. The invention is directed to the efficacious use of various neurotrophins by using them in combination with polyunsaturated fatty acids chosen from linoleic acid, gamma-linolenic acid, dihomo-gamma-linolenic acid, arachidonic acid, alpha-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid, cis-parinaric acid, docosapentaenoic acid and conjugated linoleic acid in predetermined quantities. The invention also provides methods of efficiently delivering neurotrophins to the desired areas of the brain by complexing or conjugating with PUFAs, so that they are able to cross blood brain barrier efficiently and reach the desired regions of the brain in adequate amounts.