Responses to the antidepressants (for either type) were understood using the HAM-D rating. Severe depression is diagnosable at a score of 25+ points; a notable response to the antidepressant is defined as at least a 50% reduction in the HAM-D score. This, however, does not recognize that someone who reduces their score from 30 points to 15 points may still experience heavily-impairing symptoms, which require further treatment.