Seasonal Affective Disorder

Synonyms: Seasonal adjustment disorder; winter depression; winter blues.

This is a mood disorder associated with depressive episodes and is related to seasonal variations in light. Seasonal affective disorder (SAD) can be very disabling for patients and is often missed.

Low mood during winter months has been noted as far back as 1845; however it was not formally recognised as a disorder until the 1980's.

• 2% of the population in Northern Europe have severe depression resulting from SAD.
• In the UK 1 in 50 people have SAD and 1 in 8 have milder symptoms - the latter is called sub-syndromal SAD or more commonly the "winter blues".¹
• SAD tends to present around the age of 30 and is more prevalent in women than men.
• Vulnerability to SAD is increased the further away you live from the equator.
• There is also a genetic component in that you are more likely to suffer from SAD if a close relative is affected.
• A seasonal pattern has been observed in 15% of patients with recurrent mood disorders, including unipolar and bipolar forms.

SAD is connected to reduced exposure to light during the winter months. There are several theories as to the underlying mechanism of SAD, these include:

• Changes in circadian rhythm - possibly related to the hypothalamus.
• Linked to the hormone melatonin which is secreted from the pineal gland, which itself has direct connection to the retina. Melatonin production is increased in the dark and thus there is increased production during the shorter days of winter².
• Lack of serotonin in the brain.

SAD begins around September and continues until April. The worst months are January and February.

Symptoms may be the same as depression but more atypical features may be present e.g. weight gain and over sleeping.

Patients may develop the following symptoms:

• Low mood for most of the day
• Sleep problems - including oversleeping
• Overeating with weight gain
• Lethargy
• Difficulty concentrating
• Lack of motivation
• Loss of enjoyment in life
• Family problems
• Loss of libido
• Despair
• Anxiety
• Tearfulness
• Irritability
• Physical symptoms: such as headache, palpitations and generalised aches and pains.

Diagnosis of SAD is based on ³

1. Depression cycles on a regular basis during autumn/winter
2. Full remission of symptoms in spring/summer
3. Seasonal symptoms for at least 2 consecutive years
4. Atypical features may or may not be present.

1. High index of suspicion
2. Symptom record: what are the symptoms and when do they occur
   • Diary record may help
   • SAD questionnaires may help.⁴
3. Is this SAD or another type of depression?
   • Look for atypical features
   • Look for seasonality of symptoms
   • Are there symptoms of bipolar disorder?
4. Assess for other psychiatric disorders e.g. anxiety, panic disorder.
5. Assess suicidal ideation
6. Assess abnormal mechanisms of coping e.g. social isolation, alcohol use
7. Look for and rule out organic causes of depression e.g. hypothyroidism.

Education

• About the disorder
• Self-help groups
• Simple advice: spend time out of doors, work in bright conditions, regular exercise outside, eat a healthy diet and if possible holiday to sunny areas.
• Relaxation and massage may help - but not proven.

Light therapy or Phototherapy

• Sit for 30 - 60 minutes daily in area with bright light. The light is much stronger than regular light sources, of the order of 2500-10000 lux (the greater the lux, the less time of exposure required).^3,5
• This helps two-thirds of patients. However, there are only a few randomised controlled trials.
• Can take several weeks to produce an effect, if longer than 6 weeks should seek extra help.
  However, it is not available on the NHS, although some hospital may have facilities available on site.
• Common side-effects: headache, irritability and fatigue.
• Dawn simulators are also available.
• More lux is available from natural sunlight.

Medical

• Antidepressants - SSRI's in combination with light therapy may be helpful.⁵
• Need to weigh benefits against side effect risk.

Psychological

• Family and friend support
• Psychotherapy
• Cognitive behavioural therapy.³

Experimental treatments

• Use of blue light instead of bright white light
• Vitamin D supplementation - this has been trialled in older women but the results failed to show a difference in mental scores.⁶
• Bupropion has been researched in a randomised controlled trial to review the possible prevention of SAD. Bupropion was administered by mouth from autumn to winter and was associated with a reduction in the rates of recurrence of depression.⁷
• In a very small open-label trial nefazodone resulted in improvement in sleep disturbance and depression scores.⁸