Seasonal Affective Disorder

Synonyms: SAD, 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 1980s.

• 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 winter.²
• 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 e.g. headache, palpitations, generalised aches and pains

SAD is categorised as a form of depressive disorder in DSM-IV. 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^4,5
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

• Eating disorders e.g. bulimia
• Panic attacks
• Anxiety disorder
• Attention-deficit/hyperactivity disorder

Education

• Give information about the disorder and self-help groups.
• Simple advice should include: spend more time out of doors, work in bright conditions, regular exercise outside, eat a healthy diet and if possible holiday to sunny areas.⁷
• 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).^3,7
• This helps two-thirds of patients. However, there are only a few randomised controlled trials.⁸ This is hindered by the fact that double-blind controls of light therapy are difficult to perform. Despite this, attempts at comparisons of light therapy does support that light therapy is as effective as drug therapy.⁹
• Light therapy 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 hospitals may have facilities available on site.
• Common side-effects include headache, irritability and fatigue.
• Dawn simulators are also available.
• Despite all of these more lux is available from natural sunlight.

Medical

Antidepressants - SSRIs may be helpful.¹⁰ However, they are not without risk and thus need to weigh benefits against side effect risk. There are a few trials which have compared light therapy and antidepressants. Light therapy is probably of similar efficacy but superior as less side effects.¹¹ However, further work is needed here.
Escitalopram appears to be safe and effective in the short-term.¹²

Psychological

• Family and friend support
• Psychotherapy
• Cognitive behavioural therapy³

Experimental treatments

• Use of blue light instead of bright white light.
• Use of a combination of light therapy and cognitive behavioural therapy.¹³
• Vitamin D supplementation - this has been trialled in older women but the results failed to show a difference in mental scores.¹⁴
• 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.¹⁵ It may have a role to play in prevention of SAD.

• SAD is under diagnosed in primary care and thus vigilance is required.
• Screening tools as for depression may be helpful in detecting SAD.
• There are also more specific tools for SAD e.g. Seasonal Pattern Assessment Questionnaire.^4,5
• History - try to find out the following:
  • Presence of low energy when the days get shorter and darker.
  • Problems getting out of bed up in the morning.
  • Excessive sleepiness.
  • Altered eating habits and any weight gain.
  • Any intention to self-harm or suicidal ideation.
  • Harmful coping mechanisms e.g. drugs of abuse, alcohol.
  • Any associated disorders e.g. bulimia nervosa.
• Examination - look for organic causes of depression.
• General advice - spend more time outdoors, support groups.
• Light therapy should probably be advised first line - use units that are designed for SAD. Most effective when taken early in the morning.⁶ Patients should be reviewed at 6 weeks.
• Antidepressants e.g. fluoxetine or sertraline - use if features of major depressive disorder present or lack of response to light therapy. However, the benefits and potential risks needs to be considered.
• There is no clear guidance as to the use of both antidepressants and light therapy.
• Cognitive behavioural therapy - may be effective, but is probably not an effective treatment when used alone.⁶