Seasonal affective disorder
Seasonal affective disorder is a mood disorder subset in which people who typically have normal mental health throughout most of the year exhibit depressive symptoms at the same time each year. It is commonly, but not always, associated with the reductions or increases in total daily sunlight hours that occur during the winter or summer.
Common symptoms include sleeping too much, having little to no energy, and overeating. The condition in the summer can include heightened anxiety. However, there are significant differences in the duration, severity, and symptoms of each individual's experience of SAD. For instance, in a fifth of patients, the disorder completely resolves in five to eleven years, whereas for 33–44% of patients, it progresses into non-seasonal major depression.
In the DSM-IV and DSM-5, its status as a standalone condition was changed: It is no longer classified as a unique mood disorder but is now a specifier for recurrent major depressive disorder or bipolar disorder that occurs at a specific time of the year and fully remits otherwise. Although experts were initially skeptical, the condition eventually became recognized as a common disorder. However, the validity of SAD was called into question by a 2016 analysis from the Centers for Disease Control, when it found no links between depression, seasonality or sunlight exposure.
In the United States, the percentage of the population affected by SAD ranges from 1.4% of the population in Florida to 9.9% in Alaska.
Signs and symptoms
SAD is a type of major depressive disorder, and those with the condition may exhibit any of the associated symptoms, such as feelings of hopelessness and worthlessness, thoughts of suicide, loss of interest in activities, withdrawal from social interaction, sleep and appetite problems, difficulty with concentrating and making decisions, decreased libido, a lack of energy, or agitation. Symptoms of winter SAD often include falling asleep earlier or in less than 5 minutes in the evening, oversleeping or difficulty waking up in the morning, nausea, and a tendency to overeat, often with a craving for carbohydrates, which leads to weight gain. SAD is typically associated with winter depression, but springtime lethargy or other seasonal mood patterns are not uncommon. Although each individual case is different, in contrast to winter SAD, people who experience spring and summer depression may be more likely to show symptoms such as insomnia, decreased appetite and weight loss, and agitation or anxiety.Bipolar disorder
With seasonal pattern is a specifier for bipolar and related disorders, including bipolar I disorder and bipolar II disorder. Most people with SAD experience major depressive disorder, but as many as 20% may have a bipolar disorder. Bipolar disorder is characterized by alternating episodes of depression and mania or hypomania. Depressive episodes include symptoms such as low energy, difficulty concentrating, changes in sleep and appetite, feelings of hopelessness, and suicidal thoughts. Manic episodes, which are more common in bipolar I disorder, may include elevated mood, decreased need for sleep, impulsivity, and increased activity or risky behaviors. In contrast, hypomania presents as a milder form of mania without significant impairment in daily life.It is important to distinguish between diagnoses because there are important treatment differences. In these cases, people who have the With seasonal pattern specifier may experience a depressive episode either due to major depressive disorder or as part of bipolar disorder during the winter and remit in the summer. Around 25% of patients with bipolar disorder may present with a depressive seasonal pattern, which is associated with bipolar II disorder, rapid cycling, eating disorders, and more depressive episodes. Differences in biological sex display distinct clinical characteristics associated to seasonal pattern: males present with more Bipolar II disorder and a higher number of depressive episodes, and females with rapid cycling and eating disorders.
ADHD
A study by the National Institute of Health published findings in 2016 that concluded, "seasonal and circadian rhythm disturbances are significantly associated with ADHD symptoms." Participants in the study who had ADHD were three times more likely to have SAD symptoms, and about 2.7 times more likely to have s-SAD symptoms. Those with ADHD and SAD are likely to experience sluggishness, irritability, and withdrawal. A study published in the Journal of Affective Disorders found that approximately 27% of adults with ADHD also experience SAD, with women being more susceptible than men.Cause
In many species, activity is diminished during the winter months, in response to the reduction in available food, the reduction of sunlight, and the difficulties of surviving in cold weather. Hibernation is an extreme example, but even species that do not hibernate often exhibit changes in behavior during the winter.Various proximate causes have been proposed. One possibility is that SAD is related to a lack of serotonin, and serotonin polymorphisms could play a role in SAD, although this has been disputed. Mice incapable of turning serotonin into N-acetylserotonin appear to express "depression-like" behavior, and antidepressants such as fluoxetine increase the amount of the enzyme serotonin N-acetyltransferase, resulting in an antidepressant-like effect. Another theory is that the cause may be related to melatonin, which is produced in dim light and darkness by the pineal gland, since there are direct connections, via the retinohypothalamic tract and the suprachiasmatic nucleus, between the retina and the pineal gland. Melatonin secretion is controlled by the endogenous circadian clock, but can also be suppressed by bright light.
One study looked at whether some people could be predisposed to SAD based on personality traits. Correlations between certain personality traits such as higher levels of neuroticism, agreeableness, openness, and an avoidance-oriented coping style, appeared to be common in those with SAD.
Per Pfizer, risk factors for SAD include being a female, younger age, previously being diagnosed with extreme depression or bipolar disorder, having a family history of the same disease, or living a considerable distance from the equator.
Pathophysiology
Seasonal mood variations are believed to be related to light. An argument for this view is the effectiveness of bright-light therapy. SAD is measurably present at latitudes in the Arctic region, such as northern Finland, where the rate of SAD is 9.5%. Cloud cover may contribute to the negative effects of SAD. There is evidence that many patients with SAD have a delay in their circadian rhythm, and that bright light treatment corrects these delays which may be responsible for the improvement in patients.The symptoms of it mimic those of dysthymia or even major depressive disorder. There is also potential risk of suicide in some patients experiencing SAD. One study reports 6–35% of people with the condition required hospitalization during one period of illness. At times, patients may not feel depressed, but rather lack energy to perform everyday activities.
Subsyndromal Seasonal Affective Disorder is a milder form of SAD experienced by an estimated 14.3% of the U.S. population. The blue feeling experienced by both those with SAD and with SSAD can usually be dampened or extinguished by exercise and increased outdoor activity, particularly on sunny days, resulting in increased solar exposure. Connections between human mood, as well as energy levels, and the seasons are well documented, even in healthy individuals.
Diagnosis
According to the American Psychiatric Association DSM-IV criteria, Seasonal Affective Disorder is not regarded as a separate disorder. It is called a "course specifier" and may be applied as an added description to the pattern of major depressive episodes in patients with major depressive disorder or patients with bipolar disorder.The "Seasonal Pattern Specifier" must meet four criteria: depressive episodes at a particular time of the year; remissions or mania/hypomania at a characteristic time of year; these patterns must have lasted two years with no nonseasonal major depressive episodes during that same period; and these seasonal depressive episodes outnumber other depressive episodes throughout the patient's lifetime. The Mayo Clinic describes three types of SAD, each with its own set of symptoms.
Management
Treatments for classic seasonal affective disorder include light therapy, medication, cognitive-behavioral therapy, and carefully timed supplementation of the hormone melatonin.Light therapy
Photoperiod-related alterations of the duration of melatonin secretion may affect the seasonal mood cycles of SAD. This suggests that light therapy may be an effective treatment for SAD. Light therapy uses a lightbox, which emits far more lumens than a customary incandescent lamp. Bright white "full spectrum" light at 10,000 lux, blue light at a wavelength of 480nm at 2,500 lux or green light at a wavelength of 500nm at 350 lux are used, with the first-mentioned historically preferred.Bright light therapy is effective with the patient sitting a prescribed distance, commonly 30–60 cm, in front of the box with their eyes open, but not staring at the light source, for 30–60 minutes. A study published in May 2010 suggests that the blue light often used for SAD treatment should perhaps be replaced by green or white illumination. Discovering the best schedule is essential. One study has shown that up to 69% of patients find lightbox treatment inconvenient, and as many as 19% stop use because of this.
Dawn simulation has also proven to be effective; in some studies, there is an 83% better response when compared to other bright light therapy. When compared in a study to negative air ionization, bright light was shown to be 57% effective vs. dawn simulation 50%. Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks. Certain symptoms like hypersomnia, early insomnia, social withdrawal, and anxiety resolve more rapidly with light therapy than with cognitive behavioral therapy. Most studies have found it effective without use year round, but rather as a seasonal treatment lasting for several weeks, until frequent light exposure is naturally obtained.
Light therapy can also consist of exposure to sunlight, either by spending more time outside or using a computer-controlled heliostat to reflect sunlight into the windows of a home or office. Although light therapy is the leading treatment for seasonal affective disorder, prolonged direct sunlight or artificial lights that don't block the ultraviolet range should be avoided, due to the threat of skin cancer.
The evidence base for light therapy as a preventive treatment for seasonal affective disorder is limited. The decision to use light therapy to treat people with a history of winter depression before depressive symptoms begin should be based on a person's preference of treatment.