The human brain is comprised of 77 to 78 percent water. Lipids, or fats, contribute 10 to 12 percent to brain mass, proteins make up 8 percent, 2 percent is composed of soluble organic substances, and carbohydrates and inorganic salts each contribute 1 percent.
Although composed primarily of water, the brain requires a sufficient daily intake of water to function properly. Brain cells that are deprived of too much water lose efficiency. Dehydration can cause impairment to the attention span, short-term memory, long-term memory and mathematical abilities.
The medical condition hydrocephalus, commonly referred to as water on the brain, is not actually caused by the presence of too much water in the brain. Rather, it is caused by a buildup of cerebrospinal fluid, the clear, colorless liquid that surrounds the brain and spinal cord. Hydrocephalus can occur at any time during human development and may be caused by birth defects, infections, brain hemorrhage, strokes, tumors or trauma to the head. Hydrocephalus is typically treated by one of two surgical procedures: the insertion of a drainage system called a shunt or a procedure known as endoscopic third ventriculostomy, in which tiny holes are made in the brain's ventricles to drain the fluid.