Memory

A small study showed that people with memory problems had type AB blood more than any other.

Stress

Stress boosts your body’s level of cortisol, the stress hormone. People with type A blood tend to have more cortisol, anyway. So you may have a harder time dealing with stressful situations.

Malaria

Type O blood may help ward off this disease. You can get malaria when an infected mosquito bites you. The parasite that causes it has a harder time attaching itself to type O blood cells.