All patients must meet the diagnostic criteria for recurrent major depression or bipolar mood disorder. Seasonal affective disorder (SAD) is then a sub-type specifier used to describe temporal variations of these disorders. As such, SAD is not considered a stand-alone diagnosis or comorbid condition to recurrent major depression or bipolar disorder. Common presentations include the initiation or worsening of depressive symptoms during the autumn or winter months, and full remission during the spring or summer months, or hypo-manic or manic symptoms presenting during spring or summer months.
Circadian and neurotransmitter factors are likely to contribute to the pathophysiology of SAD, although the exact mechanism of action remains ill-understood. The suprachiasmatic nucleus (SCN) of the hypothalamus is being increasingly recognised as the 'master regulator' of several systems implicated in seasonal mood regulation. Diminished light during the autumn and winter may cause a phase shift in various circadian rhythms, including sleep-wake cycle, body temperature, hormone levels, and melatonin secretion.
Adjustment disorders are commonly seen in primary care settings in which the 1-year prevalence varies from 11% to 18% of those with any clinical psychiatric disorder. A recent cross-sectional survey of 3815 patients from 77 primary healthcare centers found the prevalence of adjustment disorders to be 2.94%. A study of patients admitted through the psychiatric emergency showed that 7.1% of the adults and 34.4% of the adolescents had adjustment disorders at time of admission, though the diagnosis in some patients changed during rehospitalization. A study from Belgium by Bruffaerts et al.found adjustment disorder in 17.1% of patients presenting to psychiatric emergency setting. Among patients admitted to a public sector psychiatric inpatient unit during a 6-month period, adjustment disorder was diagnosed in 9% of patients (third most common diagnosis after psychotic illness in 62% and mood disorders in 24%