Alzheimer's Drug May Decrease Impulse Buying

Deborah Brauser

June 26, 2012

June 26, 2012 — Memantine, a receptor antagonist commonly used to treat Alzheimer's disease (AD), may also curb impulsivity in compulsive buyers, new research suggests.

A small, open-label pilot study showed that patients diagnosed with compulsive buying (CB) who were treated with memantine for 8 weeks had significantly lower scores on an obsessive compulsive shopping scale and spent significantly fewer hours and less money shopping.

"As effective treatments for CB emerge, it becomes increasingly important that physicians and mental health care providers screen...in order to provide timely treatment," Jon E. Grant, MD, from the Department of Psychiatry at the University of Minnesota School of Medicine, in Minneapolis, and colleagues write.

However, the investigators note that although "pharmacologic manipulation of the glutamate system" appears to have led to the decrease in buying behaviors, bigger and more rigorous studies are now needed to confirm their findings.

The study is published in the May issue of the Annals of Clinical Psychiatry.

Common but Unstudied Disorder

According to the researchers, CB is relatively common, affecting 1.4% to 5.8% of the general population and up to 9% of those with psychiatric disorders.

However, research on pharmacotherapy options for CB has been "limited." Memantine is an N-methyl-D-aspartate (NMDA) receptor antagonist that is commonly used to treat AD. Because it appears to "reduce glutamate excitability and improve impulsive behaviors," the investigators sought to determine whether the medication could also improve CB behaviors.

A total of 9 patients (89% women; mean age, 32 years) diagnosed with CB participated in the study between December 2008 and May 2010. The diagnosis was based on a preoccupation with buying, resulting in marked distress, social dysfunction, and financial difficulties.

The group's mean time spent shopping was 15.2 hours per week, the percentage of gross income compulsively spent in the previous years was 61%, and the mean amount spent on unnecessary purchases in the previous 12 months was $26,750.

All patients were treated with memantine, in doses ranging from 10 mg/day to 30 mg/day, for a total of 8 weeks.

The primary outcome measure was changes in behaviors from baseline to study's end on the Yale-Brown Obsessive Compulsive Scale–Shopping Version (Y-BOCS-SV).

Secondary measures included the Compulsive Buying Symptom Assessment Scale (CB-SAS), the Clinical Global Impression Severity (CGI-S) scale, the Sheehan Disability Scale (SDS), the Hamilton Anxiety and Depression Rating scales, the Perceived Stress Scale, and the Quality of Life Inventory.

Blood pressure, heart rate, and weight were measured at each office visit, which were conducted every 2 weeks. At baseline and at study endpoint, computerized neurocognitive assessments were also conducted.

Significantly Improved

Results showed that only 1 of the original participants dropped out of the study. The other 8 patients reported that the medication was well tolerated, with no serious adverse events experienced.

Dizziness (n = 3), decreased appetite (n = 1), anxiety (n = 1), and tinnitus (n = 1) were the most common treatment-related events.

For the primary outcome measure, scores on the Y-BOCS-SV decreased significantly after treatment, from a mean of 22.0 at baseline to 11.0 at the study's end (P < .001).

A significant decrease in scores was also found at the 6-week point (P < .05).

Scores were significantly decreased by study's end on the CB-SAS (32.8 to -15.4, P < .001), the SDS (15.9 to -9.3, P < .001), the CGI-S (4.4 to -1.8, P < .001), and the Perceived Stress Scale (27.1 to 17.6, P < .001).

Quality of Life Inventory scores were significantly improved (30.9 to 43.0, P < .001), as were stop-signal reaction times during the cognition tasks (P = .0097).

Although the HAM-A and HAM-D scores decreased (5.9 to -1.9 and 5.8 to -2.4, respectively), they were not deemed statistically significant.

Finally, the mean effective dose of memantine was 23.4 ± 8.1 mg/d, report the investigators.

They note that this is the first study to assess the efficacy of an NMDA receptor antagonist for treating CB.

"These findings suggest that pharmacologic modulation of the glutamate system may reduce behaviors associated with CB by improving neurocognitive function related to dysfunction of right frontal and bilateral cingulate cortices," add the researchers.

In other words, "memantine may target inhibitory control mechanisms resulting in shopping behavior despite adverse consequences."

Dr. Grant reports receiving research grants from Psyadon Pharmaceuticals and from the National Institute on Drug Abuse (NIDA). One of the other study authors also reports having received funding from NIDA. The other authors have disclosed no relevant financial relationships.

Ann Clin Psychiatry. 2012;24:119-126. Abstract

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