Does Taking Amitriptyline Cause Depression And Lack Of Motivation?

Can Amitriptyline 25MG that is prescribed for irritable bowl syndrome cause an adolescent to become depressed or lack motivation or desires. Our son was very active in sports and had some drive. He has been on it for three years. Since him having stomach issues and was prescribed this medication he seems to become depressed and having a hard time concentrating. We originally thought his stomach issues that increased his late junior year which limited his activities might have brought him down. HIs level of stress increase as a result of stomach issues which tended to make his stomach issues worse but depression had not been a issue. Thanks for your help.