One of the most common aftereffects for someone who has had an NDE is that they lose their fear of death.
To begin, you may want to read about the NDE, or to see some people's experiences.
A good book to read is Callanan, M. & Kelley, P. (1992). Final Gifts: Understanding the Special Awareness, Needs, and Communication of the Dying. New York: Bantam.
We also have a page NDEs in the Terminally Ill