Seasonal affective disorder

SIGNS / SYMPTOMS

Meets diagnostic criteria for recurrent major depressive episodes with a non-seasonal or predominantly non-seasonal pattern.

Autumn- or winter-onset SAD may be characterised more by atypical depressive symptoms, with symptom remission during the spring or summer months.

Major depressive episodes may be initiated by external stressors, whereas the SAD specifier is only temporally related.

SIGNS / SYMPTOMS

Meets diagnostic criteria for manic (bipolar I) or hypomanic (bipolar II) episodes with a non-seasonal or predominantly non-seasonal pattern.

Spring- or summer-onset of manic or hypomanic symptoms tends to be uncommon.

When this occurs in people with the SAD specifier, symptoms remit during the autumn or winter months.

SIGNS / SYMPTOMS

At least a 2-year history of persistent, low-grade depressive symptoms.

SAD shows a temporal pattern of onset and remission, whereas dysthymic disorder is chronic.

SIGNS / SYMPTOMS

At least a 2-year history of persistent, hypomanic symptoms and depressive symptoms that do not meet criteria for a major depressive episode.

SAD shows a temporal pattern of onset and remission, whereas cyclothymic disorder is chronic.

SIGNS / SYMPTOMS

Similarly to autumn- or winter-onset SAD, it is characterised by atypical depressive symptoms. However, premenstrual dysphoric disorder may also be associated with bloating and breast tenderness with onset during the later part of the luteal phase of the menstrual cycle and remission of symptoms during the follicular phase.

SIGNS / SYMPTOMS

Characterised by persistent fatigue and other associated symptoms (e.g., musculoskeletal pain, sleep disruption, memory impairments, over-exertion) lasting at least 6 months.

SAD shows a temporal pattern of onset and remission, whereas chronic fatigue syndrome tends to be chronic.

SIGNS / SYMPTOMS

Depressive symptoms may be similar to SAD, although atypical depressive symptoms are more common in SAD.

Hypothyroidism has persistent symptoms and does not show a seasonal pattern.

Hypothyroid depressive symptoms respond to thyroid-stimulating hormone (TSH) drugs.

May show other features of hypothyroidism such as cold intolerance, constipation, dry skin/hair, goitre, or delayed return of deep tendon reflexes.

SIGNS / SYMPTOMS

Central nervous system depressants may produce depressive symptoms similar to SAD.

Atypical depressive symptoms are more common in SAD.

Stimulants may produce manic or hypomanic symptoms similar to SAD.

Substance-induced symptoms show onset with substance use and remit after the substances have been metabolised by the body.

SIGNS / SYMPTOMS

Alcohol use may produce depressive symptoms similar to SAD.

Atypical depressive symptoms are more common in SAD.

Alcohol-induced symptoms show onset with alcohol use and remit after the substances have been metabolised by the body.