One study has shown the average first episode occurring at age 23, while another shows the age for first occurrence at 32. There seem to be three factors in the development of this form of depression. A biologic vulnerability based on family history and, as noted above, gender. Most people with SAD have one close relative with depression. Twin studies show a clear genetic correlation.
Light deprivation is another predisposing factor.
Diagnosis and Treatment Diagnosis of SAD is essential. Inability to complete tasks. Decreased attendance and performance at work. Your primary care physician, a psychiatrist or a therapist who is knowledgeable about depression and its seasonal variations, can provide medical assistance. Phototherapy This is the treatment of choice.