Seasonal affective disorder

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Seasonal affective disorder
Light therapy lamp for the treatment of seasonal affective disorder (SAD)

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Haleigh Williams, B.S.

Synonyms and keywords: SAD; seasonal disorder; seasonal depression; winter blues; winter depression

Overview

Seasonal affective disorder (SAD), also known as winter depression, is a form of depression that is correlated with changes in the season. In the most common form of SAD, an individual experiences more frequent depressive periods between the late fall and early spring, with no such instances in the late spring and summer months. Less commonly, patients may experience depressive episodes in the summer; this type of disorder is often referred to as reverse seasonal affective disorder.

Historical Perspective

• The seasonal variation in mood has been observed since ancient times.
• Hippocrates circa (400 BC) first explained regarding the seasonal depression.
• The Greco-Roman physicians managed depression by focussing the sunlight towards the affected individual's eyes.
• In 1894, Cook described a disorder characterized by depressed mood, low energy, fatigue, and loss of libido, which was correlated by him to the seasonal loss of sunlight.
• Esquirol(1845) and Kraplein (1921) also described the seasonal variability in the mood.
• In 1980s, SAD was systematically described for the first time and named by South African physician Normal Rosenthal. He had noticed that he felt significantly less energetic during the winters and returned to his normal state during the spring.
• In 1984, a paper was published based on Rosenthal's idea of treating depression with artificial light therapy.
• Wehr's (1989) contribution in the form of a chapter in the book Seasonal affective Disorder and Phototherapy is well-acknowledged.
• Wehr et al have also described a variant with the opposite pattern, with depressions in the summers and non-depressed phases in winters. This condition was termed as reverse-SAD.

Classification

• First in 1984, Rosenthal et al. proposed a diagnostic criteria in the form of Seasonal Pattern Assessment Questionnaire (SPAQ).
• Diagnostic criteria was included in DSM-III-R in 1987.
• According to the Diagnostic and Statistical Manual of Mental Disorders(DSM), SAD does not exist as a separate disorder.
• In DSM-5, seasonal variation in mood is mentioned as a specifier for both Major Depression disorder (Recurrent episodes) and Bipolar Disorder (both Bipolar I and II)
• The International Classification of Diseases, Tenth Edition (ICD-10) includes SAD under the category of Recurrent depressive Disorder.The characteristic of this condition is that the symptomalology appear in winter and remit during the spring season.

Pathophysiology

• The pathophysiologic basis of SAD is not completely understood.
• There is a combined effect of circadian, neurotransmitter, and genetic modulations.
• The circadian phase shift and retinal phototransduction of light are also hypothesized to be involved in the pathophysiology.
• The individuals with SAD suffer from some of the following hormonal/neurotransmitter imbalances:

1. Serotonin. Studies have shown that individuals with winter-occurring SAD produce more serotonin transporter proteins in the winter months than in the summers, causing the overall lesser effect of serotonin in winters.
2. Norepinephrine levels are also found to be low in these patients.
3. Melatonin. In the winters, as days become shorter, and periods of darkness increase. The levels of melatonin, that is produced during the night increases. This interferes with the circadian rhythm and induces lethargy.
4. Vitamin D. Patients with SAD tend to have lower levels of vitamin D than controls. This deficiency plays a role in exacerbating depression through interference with serotonin action.

Differential Diagnosis

SAD must be differentiated from diseases that present with similar symptoms, including:

• Major depressive disorder
• Atypical depression
• Bipolar Disorder
• Hypothyroidism

Epidemiology and Demographics

• The prevalence of SAD ranges from 1.5% to 9%, depending on latitude.
• Higher positive correlation has been found in case of latitude and prevalence of winter SAD. This finding was found to be prominent in the age groups over 35 years.

Age

• In most of the studies, SAD has been commonly diagnosed in younger adults.
• Compared to high-school students, SAD was found to be less prominent in adults. Winter type SAD was determined by latitude in adults whereas socio-cultural factors play a role in adolescents.
• The age of onset of SAD is generally between 18 and 30 years.

Gender

• SAD is more common in women than men. Women are four times as likely as men to be diagnosed with SAD.
• The gender differences in SAD is same as in non-seasonal depression.
• For assessing the gender-based prevalence of SAD, importance should be given to case criteria such as diagnosis (unipolar vs. bipolar), and birth cohort.

Race

• No specific racial predilection has been observed for SAD .

Risk Factors

Risk factors for SAD include:

• Female gender
• Age less than 40 years
• Higher lattitude
• Family history of depression
• 5-HTTLPR gene polymorphism
• Socio-cultural factors (for adolescents)

Screening

• The Seasonal Pattern Assessment Questionnaire (SPAQ), developed by Rosenthal in 1984, is a self-administered tool for screening SAD.
• The Seasonal Health Questionnaire (SHQ) was found to be more sensitive and specific than SPAQ . It also had higher positive and negative predictive values for SAD.

Natural History, Complications, and Prognosis

• SAD can be a serious disorder and may necessitate hospitalization.
  • There is also potential risk of suicide in some patients experiencing SAD.
  • One study reports 6-35% of sufferers required hospitalization during one period of illness.
  • The symptoms of SAD mimic those of dysthymia or clinical depression.
• With treatment, the prognosis of SAD is generally good, though some people with SAD continue to experience the full effects of the disorder throughout their lives.

Comorbidities

Commonly comorbid conditions include:

• Major depressive disorder
• Bipolar disorder
• ADHD
• Alcoholism
• Eating disorders
• Hypothyroidism

Diagnosis

Diagnostic Criteria

A diagnosis of SAD is appropriate for patients who meet all of the criteria for a diagnosis of major depression and in whom the incidence of depression has been observed to correspond to the onset of specific seasons for a period of no less than two years.

Symptoms

General symptoms of major depression include:

• Feeling depressed a majority of the time
• Feeling hopeless or insignificant
• Lethargy
• Losing interest in activities one previously enjoyed
• Having trouble sleeping
• Experiences changes in appetite or weight
• Having difficulty concentrating
• Having frequent thoughts of death or suicide

Symptoms of winter-occurring SAD include:

• Lethargy
• Hypersomnia
• Overeating and weight gain
• Craving carbohydrates and sugars
• Social withdrawal

Symptoms of summer-occurring SAD include:

• Decreased appetite and weight loss
• Insomnia
• Agitation and restlessness
• Anxiety
• Episodes of violence

Physical Examination

There is no formal, established test for SAD. A diagnosis is made by asking a patient about his/her history of symptoms.

Laboratory Findings

Though no laboratory findings are diagnostic of SAD, a healthcare professional may need to perform blood tests to rule out other disorders that present with similar symptomology.

Imaging Findings

No imaging findings are associated with SAD.

Other Diagnostic Studies

No other diagnostic modalities are associated with SAD.

Treatment

Medical Therapy

• Options for the treatment of SAD include medication, light therapy, psychotherapy, and the administration of vitamin D.
• Any of these therapies may be used on its own or in combination with another.

Medication

• SAD may be treated with selective serotonin reuptake inhibitors (SSRIs). Bupropion, a type of SSRI, has been specifically approved by the FDA for the treatment of SAD.
• Common side effects of bupropion include drowsiness, anxiety, dry mouth, dizziness, weight loss, and sore throat.
• Common side effects of SSRIs include nausea, diarrhea, constipation, vomiting, dry mouth, weight changes, and headaches.

Light Therapy

• SAD has been treated primarily with light therapy, also referred to as bright light therapy (BLT) or phototherapy, since the 1980s.
  • The rationale behind the use of light therapy is that the depressive effect of decreased sunlight during the late fall and winter months can be counteracted through daily exposure to bright light.
  • Patients who undergo light therapy typically use a light box each morning from early fall until the start of spring.
  • The use of light boxes generally calls for between 20 and 60 minutes of exposure to 10,000 lux of cool-white fluorescent light, which is approximately 20 times greater in brightness than standard lighting.
• As evidence of the efficacy of light therapy as compared to other treatment options is far from conclusive, experts recommend that decisions about forms of treatment be guided greatly by the preferences of individual patients.
• Common side effects of light therapy include eye strain and headaches.
• Light therapy is contraindicated for individuals on photosensitizing medications.

Psychotherapy

• The use of psychotherapy, specifically cognitive behavioral therapy (CBT), to treat SAD is common.
  • CBT helps patients recognize and replace depressing thoughts.
  • Patients are also encouraged to engage in activities they find pleasing and engaging as a technique for coping with their symptoms.

Vitamin D

• Though the administration of vitamin D has not been proven to be an effective treatment for SAD, researchers have postulated that it may be helpful due to decreased vitamin D levels observed in SAD patients.
  • Studies intended to determine the efficacy of vitamin D as a treatment for SAD have yielded mixed results.

Surgery

Surgery is not recommended for the management of SAD.

Prevention

• There are no established measures for the primary prevention of SAD.
• Measures for the secondary prevention of SAD include:
  • Getting an adequate amount of sleep
  • Eating a healthy, balanced diet
  • Taking medicine as directed
  • Exercising regularly
  • Avoiding alcohol and illegal drugs