dr. gardner believes that symptoms of mental disorder are distributed on a normal curve, and he finds people across the full range. for him, there is no magic threshold at which people have the disorder. he prefers to use the level of distress or impairment as a guide to diagnosis. dr. gardner... uses the diathesis-stress approach to classifying mental disorders. approves of the current mental health system agrees with a dimensional approach to the classification of disorders agrees with an approach to the diagnosis of mental disorders that uses categorical classification.