Age regression is a coping mechanism used by people often with ptsd, anxiety, depression or simply any sort of childhood trauma/stress. Some regressors will regress back farther then others. Ways you could possibly tell someone is a regressor, Babbling/Slurring words, Doing childish activites, Pacifiers, Stuffies, Bottles, Thumb sucking ect. A lot of people mistake age regression for age play. Age regression and age play are both very different. Age play is a kink whilst age regression is a coping mechanism.
"Hey why do ze have a pacifier?" "Oh it's because xe use age regression as a coping mechanism." "Oh nice!"