This type of research needs to be controlled for age. The body of an 80 year old person is materially different from that of a 20 year old and that might change

This type of research needs to be controlled for age. The body of an 80 year old person is materially different from that of a 20 year old and that might change their outlook on life drastically. An unbiased researcher would seek out the regrets of dying 10 year olds, 20 year olds, 30 year olds etc etc