Hypomania Induced by Adjunctive Lamotrigine
To the Editor: Adjunctive and monotherapeutic lamotrigine has been effective in the treatment of bipolar (1–4) and unipolar (3, 5) mood disorders. We present a case of potentiation with lamotrigine for major depression that was partially responsive to antidepressants, in which the patient developed hypomania. This is, to our knowledge, the first such reported case.
Ms. A was a 23-year-old woman with a DSM-IV diagnosis of major depression and no personal history of bipolar illness and no family history of mood disorders. She had a partial response to 6 months of combination cognitive therapy and buproprion, 300 mg/day. The buproprion was increased to 400 mg/day for 3 months without further improvement. Lamotrigine was then added. After 1 week of 25 mg at bedtime, Ms. A reported an improved mood. After another week at 50 mg/day, she noted a further improved mood, decreased anxiety, and increased energy. Two weeks later, her lamotrigine dose was increased to 75 mg/day. One week thereafter, she reported decreased sleep (2–4 hours per night), increased energy, distractibility, mood lability, and increased spending. She reported no grandiose or other delusions but scored 9 on the Altman Self-Rating Mania Scale (6) (a score >6 suggests hypomania or mania), and she met DSM-IV criteria for hypomania. Her lamotrigine dose was reduced to 50 mg at bedtime. Two weeks later, the hypomanic symptoms subsided (Altman Self-Rating Mania Scale score=5). Fourteen months later, Ms. A remained euthymic.
All antidepressants can induce hypomania or mania in susceptible unipolar patients when they are given in combination or at a high dose. Our patient’s hypomanic state is further evidence that lamotrigine has potentiating antidepressant properties, likely through its ability to decrease glutamate release, thereby reducing binding to the N-methyl-d-aspartate receptor complex (4). This case report supports lamotrigine’s role as an adjunctive and potentiation treatment in partially responsive unipolar depression.
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