Memantine, a drug typically used to treat symptoms of Alzheimer’s disease (AD), is linked to a significant reduction in symptoms of trichotillomania and skin-picking disorder, new research shows.

Results from the double-blind, placebo-controlled trial showed that 61% of participants who received memantine were “much or very much improved,” vs 8% in the placebo group.

“Memantine was far more effective than placebo,” lead investigator Jon Grant, MD, MPH, professor of psychiatry and behavioral neuroscience at the

University of Chicago in Illinois, told Medscape Medical News. “However, while subjects responded favorably, that didn’t necessarily mean there were no symptoms.”

The study was published online February 22 in The American Journal of Psychiatry.

Underrecognized, Disabling

Investigators note that trichotillomania and skin-picking disorder are underrecognized and are often disabling conditions. However, the researcheres point out that with prevalence rates of 1.7% for trichotillomania and 2.1% for skin-picking disorder, they are not uncommon.

Behavioral therapy that attempts to reverse these habits is considered first-line treatment, but trained therapists are difficult to find. In addition, the investigators point out that currently, there are no US Food and Drug Administration (FDA)–approved medications for either disorder, and pharmacologic clinical trials are relatively uncommon.

The existing data from double-blind, placebo-controlled studies support the use of the antipsychotic olanzapine, the tricyclic antidepressant clomipramine, and the supplement N-acetyl-L-cysteine (NAC). Grant also noted that previous drug trials involving patients with trichotillomania have been very short in duration.

Prior research has implicated the glutamate system in repetitive motor habits and the urges that drive them. Memantine, a glutamate receptor antagonist, targets excessive glutamatergic drive. To investigate whether this medication may be beneficial for patients with trichotillomania and skin-picking disorders, the investigators conducted a randomized placebo-controlled trial.

The study included 100 adults (86 women; mean age, 31.4) with trichotillomania, skin-picking disorder, or both; participants received memantine (n = 55) or placebo (n = 45) for 8 weeks; they received memantine 10 mg or placebo for the first 2 weeks, then 20 mg for the next 6 weeks.

The researchers, who were blinded to assignment, assessed participants every 2 weeks using the National Institute of Mental Health Trichotillomania Symptom Severity Scale, which was modified to include questions for skin- picking disorder.

The team also tracked symptoms and behaviors using additional scales, including the Sheehan Disability Scale and the Clinical Global Impressions severity scale.

At the study’s conclusion, 79 patients remained. Of those, 26 of the 43 participants in the memantine group were “very much” or “much” improved (61%), vs 3 of 36 (8%) in the placebo group. (P< .0001)

Six participants in the memantine group experienced complete remission of symptoms, compared to one in the placebo group. There were no differences between the study groups in terms of adverse events.

Study limitations included the relatively short length of the trial for what should be considered a chronic disease, as well as the inclusion of only mildly to moderately symptomatic participants.

Grant said that he would like to study how memantine works in combination with behavioral therapy.

“Two Great Options”

Commenting on the findings for Medscape Medical News, Katharine Phillips, MD, professor of psychiatry at New York–Presbyterian Weill Cornell Medicine, said she has been using memantine for “quite some time” to treat her patients with skin-picking disorder, adding that she uses higher doses of the drug than were tested in the study.

She noted that both NAC and memantine affect glutamate, an amino acid in the brain that is likely involved in repetitive physical or motor habits, such as hair pulling and skin picking.

“The good news is that we have two great options” for the treatment of trichotillomania and skin-picking disorder, said Phillips, and that both are easy to tolerate.

Future research should focus on longer trials of memantine and at higher doses, as well as other glutamate modulators, she said.

The study was funded by departmental research funds at the University of Chicago. Grant reported receiving research funding from Biohaven Pharmaceuticals and Janssen, as well as yearly compensation from Springer Publishing for his role as editor-in-chief of the Journal of Gambling Studies. He has also received royalties from American Psychiatric Publishing, McGraw Hill, Oxford University Press, and WW Norton. Phillips reported receiving royalties from American Psychiatric Publishing and an honorarium from the Merck Manual.

Am J Psychiatry. Published online Feb 22, 2023. Abstract

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