Neanderthal genes may explain why some people have Chiari malformation type I, a condition in which the brain bulges out of the back of the skull.

Experts suggest that puzzles help curb cognitive decline because they expand the brain's cognitive reserve, or the ability to solve and cope with problems. Activities to try include putting together jigsaw puzzles or solving other types of puzzles, such as Sudoku, crosswords, memory games and math problems.

For the first time, researchers at the Netherlands Institute for Neuroscience and Amsterdam UMC have identified what happens in neural networks deep within the brain during obsessive thoughts and compulsive behaviors.