Major depressive disorder is likely to have a
number of causes. Middle-aged or elderly patients
presenting with depression may have a disorder
related to cardiovascular disease and originating
from endothelial dysfunction.Patients in their
late teens or early 20s who have severe depression
may have important genetic risk factors and a high
risk of manic episodes.In patients with an anxious
and depressive personality, depression may
be due to genetically determined personality factors11
or adverse childhood experiences.