Adam trained with Warriors during the 2016/2017 and was included in the squad that faced Ospreys at Scotstoun in November.
The prop, a product of Fife club Dunfermline and Queen Anne High School, currently plays for Premiership side Stirling County.
He came off the bench to receive his first cap for Scotland U20 in the opening game of the 2016 Six Nations, a 24-6 defeat of England.
He started at prop for Scotland U18 against England, in Newcastle, in March 2015, and went on to claim five caps at that level.