The Diagnostic and Statistical Manual of Disorders, used by physicians in the US, contains criteria for seasonal affective disorder, defining it as a sub-type of depression or bipolar disorders rather than a separate condition. Subsyndromal SAD is the label given to the mildest and most common form of winter SAD.
Symptoms of Winter SAD
Winter SAD can affect both adults and children, usually presenting with a young adult onset. People with winter SAD will experience some of the following symptoms (list adapted from the DSM-IV-TR):
- Low mood (irritable mood in children or adolescents)
- Notable loss of pleasure in most, if not all, activities
- Notable changes in appetite and/or weight
- Sleeping too much or too little
- Slowing of psychological and physical activity
- Fatigue, energy loss
- Feelings of worthlessness, excessive guilt
- Difficulty concentrating and/or making decisions
- Recurrent thoughts of death, suicidal ideation
People with winter SAD are more likely to experience the atypical symptoms of depression, such as appetite increase, weight gain and sleeping too much, rather than decrease in appetite, weight loss and insomnia. Other atypical symptoms include irritability, rejection sensitivity and leaden feelings in the limbs (leaden paralysis).
Winter SAD and Diagnosis
For winter SAD to be diagnosed using the DSM-IV-TR, the person must experience several of the above mentioned symptoms, always including either low mood or loss of pleasure. A regular seasonal pattern is essential, as is ruling out other conditions and ensuring seasonal stressors are accounted for.
Prevalence of Winter SAD
In 1998, the British Journal of Psychiatry published “Epidemiology of recurrent major and minor depression with a seasonal pattern: The National Comorbidity Survey”, surveyed 8098 subjects in 48 states in the US, using DSM criteria. Authors DG Blazer et al reported, “The lifetime prevalence of major depression with a seasonal pattern was 0.4%, and the prevalence of major or minor depression with a seasonal pattern was 1%.”
In his article Seasonal Affective Disorder in Healthy Minds, the American Psychiatric Association’s online resource, author Douglas Jacobs says it’s believed that 10-20% of people in the US are affected by some form of SAD. Jacobs also notes that SAD appears more common in women. However, men are less likely to come forward with symptoms of depression.
Winter SAD is frequently reported as being more prevalent in northern latitudes, however, this is a gray area. In the book “Seasonal Affective Disorder: Practice in Research”, published by Oxford University Press, authors Tim Partonen et al point out that there are an equal number studies rejecting latitude-prevalence as there are supporting it.
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