Cholesterol concentration is highest in the brain. The level of cholesterol in the blood influences production of protective hormones such as progesterone and testosterone. Most of these hormones are contained in the brain.
Cholesterol is used by the body to heal injuries to the arterial walls, forming a bandage of sorts over the injury. High density lipoprotein cholesterol (HDL), the good kind, is involved in repair work. Low and very low density cholesterol (LDL and VLDL) can be the bad kind that is likely to be involved in causing damage.
In this case, cholesterol is the ambulance. Like the ambulance, cholesterol helps people when they're in health trouble. Cholesterol, however, often gets the entire blame.
It is believed by many that high cholesterol levels alone lead to heart and blood vessel damage because the two are often found together. It is possible that the same process that causes heart problems, such as injury to arteries, also causes an increase in cholesterol to help repair the damage. Cholesterol, in this case, does not cause the damage, but attempts to cure it.