Zach McLeod was only 16 when he suffered a serious head trauma while playing football. Surgeons were able to save Zach’s life, but they were not able to save portions of his brain. After the accident, Zach was no longer able to see to the right of center, lost the majority of his ability to speak and short term memory, and could no longer walk well without someone’s help.

Zach, who is now 27, lives in a group home in Brookline, takes classes at Boston University, and rows on the Charles River. Despite the hardships he has endured, “Zach is without a doubt, the happiest, most loving person that I think I’ve ever known,” said his dad, Pat McLeod.

Pat and Zach’s mother, Tammy, are both chaplains at Harvard. They have spent their lives guiding others through life’s ups and downs, but were at a loss after Zach’s accident. Even with all their experience, they couldn’t figure out a way to properly grieve. Zach was still alive, but no longer the person he was.

“They talk about this linear process of letting go and they talk about closure, but there is no closure because Zach’s still here,” Tammy said during an interview with Boston Public Radio Monday. It took Tammy five years to find the term she was looking for, ambiguous loss.

As Tammy explains it, there are two types of ambiguous loss. The first type is when you don’t have the person but you still have them psychologically, like a kidnapping or a POW. The second type, which the McLeod’s experience, is when you have the person but you don’t have them in the same way, like an addiction, dementia, or in their case, Zach’s brain damage.

Tammy and Pat have written about their struggle with grief and ultimate acceptance of Zach’s new persona is in their new book, “Hit Hard: One Family's Journey of Letting Go of What Was — And Learning to Live Well with What Is." They both joined BPR Monday to talk about Zach, their lives and what has brought them salvation.