Seasonal Affective Disorder
Conventional Treatment of SAD
First-line treatment for SAD is light therapy. During light therapy, patients are exposed to bright light early in the morning in an attempt to reduce the secretion of melatonin and stimulate a more natural waking cycle. Studies of patients with SAD indicate that bright light therapy in the morning produces greater therapeutic effect than evening light (Eastman 1998; Lewy 1998b).
Although bright light therapy is an effective method for treating SAD, some people do not respond due to side effects or lack of adherence to its use (Pjrek 2004). Lack of adherence may result from inconveniences associated with bright light therapy. First, bright light therapy is most effective if used early in the morning, but patients with SAD may have difficulty waking up (Lewy 1987a,b; Terman 2001; Pjrek 2004). Second, the devices used can be expensive and may not be covered by insurance (Pjrek 2004). Finally, light therapy is time consuming, with most studies recommending 30 to 45 minutes of direct exposure to the light source.
In addition to light therapy, a number of drugs may be prescribed, including the following:
Selective serotonin reuptake inhibitors. The selective serotonin reuptake inhibitors (SSRIs) fluoxetine and sertraline are the two antidepressants most commonly studied in the treatment of SAD (Lam 1995; Moscovitch 2004). SSRIs inhibit serotonin reuptake within synapses (Potter 2001), thus making more serotonin available to interact with serotonin receptors. Studies have also been conducted to determine the effects of SSRIs on melatonin levels in patients with SAD. Results have shown that fluoxetine significantly reduces melatonin levels in these patients, while other antidepressant agents (eg, tricyclics) elevate melatonin levels (Childs 1995). Because of the natural fluctuation in melatonin levels throughout the day, timing of SSRI administration may be an important consideration to ensure levels of melatonin are reduced at the appropriate time (ie, in the morning).
Selective noradrenaline reuptake inhibitor. Reboxetine is a novel selective noradrenaline reuptake inhibitor available in European countries; its application for approval in the United States has been denied by the Food and Drug Administration (FDA). It has been shown to be effective in treating depression (Kasper 2000). A dose of 8 mg reboxetine daily has been shown to relieve both depressive and atypical symptoms associated with SAD within 2 weeks. Side effects included dry mouth and constipation, but they were generally transient and mild in intensity (Hilger 2001).Modafinil. Modafinil, a drug known to promote wakefulness, has been studied in the treatment of SAD (Lundt 2004). Modafinil is thought to selectively promote wakefulness by influencing the sleep-wake centers of the brain (Scammell 2000). Studies using modafinil in the treatment of narcolepsy and major depressive disorder have indicated that modafinil can improve wakefulness and reduce fatigue (DeBattista 2003; Menza 2000). In a study of treatment with 100 mg modafinil during week 1, followed by 100 mg or 200 mg for weeks 2 to 8, modafinil significantly improved SAD symptoms, reduced fatigue, and was well tolerated (Lundt 2004).