A University of Rochester research review emphasizes that SAD is actually a subtype of major depression and should be treated as such. Their review article appeared in the American Academy of Family Physicians.
Lead author Stephen Lurie, M.D., Ph.D., an assistant professor of Family Medicine at the University of Rochester Medical Center, also noted that SAD is sometimes missed in the typical doctor's office setting.
"Like major depression, Seasonal Affective Disorder probably is under-diagnosed in primary care offices," Lurie said. "But with personalized and detailed attention to symptoms, most patients can be helped a great deal."
New, preliminary studies link SAD to alcoholism or Attention Deficit Hyperactivity Disorder (ADHD). However, all people with SAD will not have ADHD.
"The important message here is that if you are a patient who has been diagnosed with a mental illness of any kind, don't just assume that any new mental or emotional problem is due to that illness," Lurie said. "Specifically, if you have ADHD and you feel worse in the winter, don't just assume it's your ADHD getting worse. It could actually be SAD - and you should see your doctor because ADHD and SAD are treated entirely differently."
Although SAD has only been studied in adults, parents of children with ADHD should be sensitive to seasonal patterns of behavior and report any changes to a doctor, Lurie said.
Emerging evidence also shows that a pattern of seasonal alcohol use or abuse is associated with SAD. Patients might be self-medicating to cope with an underlying depression, researchers said.
Treatment for SAD includes light therapy, medications such as antidepressants, and cognitive behavior therapy. Each option seems to be effective, Lurie said, but none has been proven superior.
For some patients, SAD is precipitated by darker days causing a shift in 24-hour hormonal rhythms. The loss of natural light outdoors can be replaced with treatment by indoor light-therapy units designed for SAD. Light therapy is best delivered in the morning, when it can regulate the daily pattern of melatonin secretion, the review said.
Treatment with cognitive therapy has been shown to improve a person's dysfunctional thoughts and attitudes and other symptoms in patients with major depression, but no large studies have established whether this type of treatment is effective for SAD.
Doctors often prescribe antidepressants such as Zoloft for SAD. But most of the clinical studies have compared the drug therapy to a placebo pill rather than to light therapy, making it difficult to determine if one treatment is better, the review said.