A method of measuring Reelin as a biomarker, to non-destructively assess or predict DHA levels in the brain and in other, currently inaccessible or difficult-to-access, key components of the 
central nervous system (CNS) is described. Also described is a method to prevent, 
delay the onset of, or treat Reelin deficiency or dysfunction and / or a 
disease or condition associated with Reelin deficiency or dysfunction, comprising administering to a patient diagnosed with or suspected of having a Reelin deficiency or dysfunction an amount of a PUFA, and particularly an 
omega-3 PUFA, and more particularly, 
docosahexaenoic acid (DHA) or a precursor or source thereof, to compensate for the effects of Reelin deficiency or dysfunction in the patient. Also described is a method to prevent or reduce developmental defects or disorders associated with Reelin dysfunction or deficiency through the supplemental use of polyunsaturated fatty acids (PUFAs—unsaturated fatty acids having two or more double bonds), and particularly highly unsaturated fatty acids (HUFAs—unsaturated fatty acids having three or more double bonds), and more particularly a HUFA selected from 
arachidonic acid (ARA), eicosapentacnoic acid (EPA), 
docosahexaenoic acid (DHA) and 
docosapentaenoic acid (DPA), and even more particularly 
omega-3 HUFAs, and more particularly DHA, to: compensate for reduced 
fatty acid binding protein or function thereof in the patient; compensate for reduced brain 
lipid binding protein or function thereof in the patient; improve the activity of 
fatty acid binding proteins in the patient; increase the expression of brain 
lipid binding proteins (BLBPs) in the patient; improve at least one parameter of the 
mechanism of action of brain 
lipid binding proteins in the patient; overcome a deficiency of DHA in 
central nervous system (CNS) structures and improve the resulting function thereof; increase the incorporation of functional DHA and other PUFAs into the 
phospholipid membranes of glial cells and neurons in the patient; increase the level of Reelin and / or improve the activity of Reelin in the patient; and / or improve at least one symptom of a 
disease or condition associated with Reelin deficiency or dysfunction.