People who take statin drugs to lower their cholesterol often become depressed, and anxious, and they start suffering from memory loss - and now scientists have worked out why this happens. The brain needs serotonin, an enzyme, in order to control mood and behaviour - but taking a statin for a long time changes the structure of the cells that are sensitive to the enzyme. They tested the theory with the statin drug mevastatin. They noted significant changes to the structure and function of serotonin cell receptors - and they resumed normal functioning only when cholesterol levels were restored to normal. In other words, we need cholesterol in order to maintain a healthy and well-functioning brain, and the cost to our lifestyle of the statin may be a price too high to pay. (Source: Biochemistry, 2010; 49: 5426).