Different studies have describedchanges in the abundance and distribution of several of these lipidspecies in AD.21−27 Several attempts to alleviate the deficit of ACh in AD patientsby the administration of cholinergic enhancers or precursors suchas Ch or lecithin have failed, while those based on phosphatidylserine,Ch-alphoscerate, and CDP-Ch displayed slight benefits (reviewed inref (28)). Here, C4B is linked to Alzheimer disease.