Do open hand slaps to the head of a adult cause brain damage?

Asked & answered: The brain as an important organ is surrounded by protective layers. The skin of the head & skull are good at absorbing trauma. Inside the skull are layers of protection like bubble wrap, supported by a layer of fluid that absorbs trauma. What you describe sounds minimal & unlikely to trigger any damage.

Brain damaged: People who engage in behavior like the one you described are already brain damaged. Have a healthy diet, exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Get HPV vaccine. Wish you good health!