Ep 140 – Seasonal affective disorder

Seasonal affective disorder (SAD) is a form of depression that occurs at specific times of the year, most commonly during the autumn and winter months when daylight hours are shorter. Characterised by symptoms such as persistent sadness, fatigue and changes in appetite or sleep patterns, SAD is more than just the "winter blues." It is a clinically recognised but often underdiagnosed condition that can significantly impact an individual's quality of life. In this episode, Dr Roger Henderson looks at how to diagnose SAD as well as the causes, symptoms and treatment options in primary care.

Key take-home points

• SAD typically begins during the ages of 20 to 30, with women affected three- to five-times more frequently than men.
• The incidence of SAD may be higher in some populations, such as those with anxiety, attention deficit hyperactivity disorder (ADHD) or premenstrual dysphoric disorders.
• The exact cause for SAD remains unclear but it appears to be linked to the impact of sunlight in triggering the release of mood-altering chemicals such as melatonin and serotonin.
• All patients with SAD must meet the diagnostic criteria for bipolar mood disorder or recurrent major depression.
• While not considered a unique diagnostic entity itself, SAD is classified as a sub-type specifier used in describing temporal variations in bipolar or recurrent major depressive disorders over at least a 2 year period.
• Common presentations of SAD include the initiation or progression of depressive symptoms during autumn or winter months, full remission during spring or summer months or symptoms of hypomania or mania during spring or summer.
• There are typically no objective findings from physical examination.
• Treatment of SAD depends on its severity.
• A pure clinical depression should be treated conventionally with anti-depressants and cognitive behavioural therapy, tailored to suit that particular individual.
• For many sufferers of SAD, the most effective therapy is using light boxes.
• Relative contraindications for light therapy include retinal disease, macular degeneration and the current use of photosynthesising medicines.
• Clinical improvement in symptoms with light therapy may be observed within 1 to 3 weeks of consistent administration. If light therapy is discontinued, symptoms may relapse within a similar period.
• The optimal dosing of light therapy is at least 5000 lux/day, which may involve 2 hours at 2500 lux or 30 minutes of 10,000 lux intensity, during the early morning hours or on rising.
• Although few randomised, controlled trials studying antidepressant therapy for SAD are available, fluoxetine and sertraline have been shown to help.
• All patients with autumn-onset or winter-onset depression should be subject to screening for spring or summer hypomania or mania symptoms.
• An estimated one in five people with SAD may present with a bipolar disorder.
• SAD tends to be a recurring condition, with up to 70% of patients experiencing recurrent autumn or winter depressive episodes.
• Untreated SAD can be associated with heavy primary-care utilisation. Compliance with treatment options is essential, as relapse can be rapid when light therapy is discontinued prematurely.

Key references

1. Meester Y, Gordijn MC. Psychol Res Behav Manag. 2016;9:317-327. doi: 10.2147/PRBM.S114906.
2. NICE. 2022. https://www.nice.org.uk/guidance/ng222.
3. Yildiz M, et al. Psychiatr Danub. 2016;28(1):25-29.
4. Forneris CA, et al. Cochrane Database Syst Rev. 2019;5(5):CD011270. doi: 10.1002/14651858.CD011270.pub3.
5. Nussbaumer-Streit B, et al. Cochrane Database Syst Rev. 2021;3(3):CD008591. doi: 10.1002/14651858.CD008591.pub3.
6. Nussbaumer-Streit B, et al. Cochrane Database Syst Rev. 2019;3(3):CD011269. doi: 10.1002/14651858.CD011269.pub3.
7. Mind. https://www.mind.org.uk/information-support/types-of-mental-health-problems/seasonal-affective-disorder-sad/about-sad/.