Dr. Gupta examines the impact of concussions around soccer and shares the story of 16-year-old Gracie Hussey who is dealing with the effects of having two concussions from the sport.

The potential end of polio in Africa is beginning to become a reality; Sanjay Gupta is in northern Nigeria to document what was once impossible task.

Addiction's total loss of all control and obsessive cravings threatens peoples' relationships, school, work and lives.