With time, and the patience of a carer named Nurse Esther, however, Beah says he was eventually able to reconnect to his lost childhood and remember the person he once was.
He also credits the hip-hop music he loved as an innocent 12-year-old and the songs of Bob Marley as a major help in his recovery.
Beah's progress was so impressive that in 1996 he was selected to go to the United Nations and speak to a conference led by Graca Machel, Nelson Mandela's wife, on the plight of child soldiers.
It was during this trip that he would meet Laura Sims -- a UNICEF worker who would eventually adopt him and bring him to America when the conflict in Sierra Leone escalated to engulf Freetown in 1998.
Upon moving to the U.S., Beah enrolled at the United Nations school in New York before going on to graduate with a law degree from Oberlin University in Ohio.
During his studies he also wrote a book on his experiences as a youth in Sierra Leone, "A Long Way Gone: Memoirs of a Boy Soldier".
"I finished this book before I graduated. I never intended to publish it but the idea for writing it was really this desire to just find a way to give the human context that was missing in the way the issue of child soldiers were discussed," he says.
His passion for bringing a greater understanding to the experiences of child soldiers has since led Beah to his current role as a U.N. ambassador for children affected by war.
And he hopes to offer the same support to today's child soldiers as Nurse Esther and the staff at the Freetown rehab center offered him.
"I witness UNICEF workers doing all of this and when these children were removed I felt their confusion," he says.
"I've been in that place before. All of a sudden you no longer have your military gear, you're now a kid."
"What I'm saying to them is that everybody has the capacity to find their own talent with the right opportunities to do something more with their lives, and everybody can walk their own path."