Academic aptitude is a negligible factor when TPR is applied by a skilled and talented teacher. Everyone is surprised when disadvantaged children who experience difficulty in class after class in a traditional school, enjoy success in a TPR class. In a traditional class, adults endure the handicap of sitting in rows of chairs while an instructor performs and performs and performs. In a TPR class, the students perform and perform and perform while the instructor is the director of the play. Note that this is exactly how children acquire another language so quickly while living in a foreign country.
Children are silent but respond to directions from caretakers and other children.
This is a linguistic luxury that their parents living in the same country do not experience. Retention with TPR is analogous to riding a bicycle. Even if years have elapsed since acquiring the skill, after a few warm up trials, proficiency returns. TPR seems to work effectively for children and adults. There is no age barrier.