History and exam
Key diagnostic factors
common
≥2-year period of seasonally related changes in mood
In which patients meet diagnostic criteria for a major depressive episode, bipolar I disorder, or bipolar II disorder.
Patients may have a history of nonseasonal major depressive, manic, or hypomanic episodes, but seasonally related episodes should substantially outnumber nonseasonal episodes.[39]
fall or winter depression
Most common presentation of SAD.
At least a 2-year history of seasonal depressive symptom onset.
Atypical depressive symptoms likely to occur during this time (e.g., hypersomnia, hyperphagia with carbohydrate cravings, weight gain, irritability, slowed movement, and heaviness in the limbs).
spring or summer symptom remission
Most common presentation of SAD.
At least a 2-year history of seasonal depressive symptom remission.
atypical depressive symptoms
Including hypersomnia, hyperphagia with carbohydrate cravings, weight gain, irritability, slowed movement, and heaviness in the limbs.[43]
Common in people with fall- or winter-onset SAD.
vegetative depressive symptoms
Sad mood, restricted affect, loss of interest, poor energy, psychomotor agitation or retardation, feelings of hopelessness, helplessness, worthlessness, or inappropriate guilt, concentration difficulties, indecisiveness, and thoughts of suicide are common in SAD.[41]
Vegetative depressive symptoms are more common than atypical depressive symptoms in spring- or summer-onset SAD.
They may also occur in people with fall- or winter-onset depression.
uncommon
spring or summer manic or hypomanic symptoms
Less common presentation of SAD.
At least a 2-year history of seasonal onset of manic or hypomanic symptoms.
Approximately 25% of bipolar disorder cases may have a seasonal component.[9]
Within bipolar disorders, a seasonal pattern may be more common among patients with bipolar II disorder compared with those with bipolar I disorder.[49]
spring or summer depression
Less common presentation of SAD.
At least a 2-year history of seasonal depressive symptom onset.
Vegetative depressive symptoms are more common than atypical depressive symptoms with a spring or summer onset.
manic/hypomanic symptoms
Bipolar symptom presentations are less common but can appear during spring or summer months.
Abnormally expansive or irritable mood, inflated self-esteem and grandiosity, decreased need for sleep, pressured speech or increased frequency of talking, racing thoughts, distractibility, increased goal-directed activity, or excessive engagement in pleasurable activities with a high degree of risk (e.g., spending, sexual activity).
Other diagnostic factors
common
somatic symptoms
behavioral withdrawal
Withdrawal, avoidance behavior, and disengagement from usual activities may compound functional impairments and increase the burden of care.
functional impairments
Common in personal, social, and occupational domains.
uncommon
excessive alcohol use
May develop to regulate negative affect and should be routinely assessed in the clinical setting.
Functional impairments are common in this group.
tachycardia
May be found if there is heightened sympathetic nervous system activity with manic or hypomanic symptoms.
increased systolic blood pressure
May be found if there is heightened sympathetic nervous system activity with manic or hypomanic symptoms.
restlessness
May be found if there is heightened sympathetic nervous system activity with manic or hypomanic symptoms.
Risk factors
strong
exposure to diminished light during winter and increased light during summer
Diminished light during winter months and increased light during summer months may contribute to risk for seasonal-mood variations.[23]
family history of seasonal affective disorder (SAD)
female sex
Approximately 3 to 5 times more likely among women, which is a greater sex difference than that observed in nonseasonal depression.[16]
age 20 to 30 years
Average age of onset is between 20 and 30 years, with declining rates in older populations.[15]
weak
residing at a northern latitude
Slightly higher incidence of SAD in northern latitudes.[3][6]
Although the latitude-SAD association has been demonstrated in North American samples, this finding has not been reliably replicated in European cohorts. This suggests the influence of other factors, such as genetic variability, cultural differences, and climate.[7]
Symptoms may greatly diminish or remit with travel to southern latitudes, due to increased daytime light exposure.[15]
psychological factors (e.g., high neuroticism)
Although associated, the role of psychological risk factors is diminished in the diagnostic criteria for SAD. For example, patients with marked neuroticism may be more prone to experiencing distress in general, and thus likely present with more nonseasonal depressive episodes.[38]
psychiatric comorbidity (e.g., anxiety, ADHD, premenstrual dysphoric disorders)
alcohol use
Cause and effect are not established. Genetic disruptions in circadian rhythm gene functions may partially account for an association between SAD and alcohol-use disorders.[36]
Alcohol use may increase in association with seasonal mood changes as a means of coping with SAD symptoms in some populations.[14]
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