The degradation and regeneration of myelin sheaths characterize neurological disorders such as multiple sclerosis. Cholesterol is an indispensable component of myelin sheaths. The cholesterol for the regenerated myelin sheaths must therefore either be recycled from damaged myelin or produced again locally. In a recent study, scientists at the Max Planck Institute for Experimental Medicine in Göttingen, led by Gesine Saher, found that in the case of chronic damage, unlike in acute damage, hardly any cholesterol is recycled. Instead, the new production of cholesterol determines the efficiency of the repair. Unexpectedly, not only the myelin-forming cells themselves but also nerve cells make an important contribution to regeneration. Cholesterol synthesis in nerve cells ensures the replenishment of newly myelin-forming cells. This could impact the therapeutic success for myelin disorders such as multiple sclerosis.