Gabapentin for Behavioral Dyscontrol With Mental Retardation

Ms. A was a 23-year-old woman who suffered from profound mental retardation due to Cornelia de Lange syndrome. She had severely limited motor and communication skills (speaking few and isolated words), difficulties adapting to environmental changes, and inadequate sphincter control.

Maladaptive behavior had appeared for the first time when she was 18 years old. She had been treated as an outpatient and given oral risperidone, 1 mg/day, and diazepam, 5 mg/day, resulting in significant remission of her symptoms. Three years later, agitation, hostility, self-destructive behavior, and screaming had reemerged and had been unsuccessfully treated on an outpatient basis with increases in her medication doses (up to 4 mg/day of risperidone and 30 mg/day of diazepam). Finally, 4 months later, Ms. A was admitted to our psychiatric clinic, but despite the alteration of her medications, her condition remained unchanged. Her last drug regimen included 5 mg t.i.d. of orally administrated haloperidol drops, 25 mg t.i.d. of chlorpromazine, and 4 mg b.i.d. of extended-release biperidin; lorazepam, 2 mg given intramuscularly, was used on an as-needed basis.

Oral gabapentin, 400 mg/day, was added, and after a few days it was increased to 800 mg b.i.d. As a result, a remarkable improvement was noticed. All drugs were gradually tapered, and Ms. A’s medications were adjusted to 5 mg/day of haloperidol, 400 mg/day of gabapentin, and 4 mg/day of extended-release biperiden without any aggravation of her symptoms. When gabapentin was withdrawn, Ms. A’s behavioral dyscontrol reemerged within 48 hours. Gabapentin, 400 mg/day, was reintroduced, resulting again in improvement. Haloperidol was further tapered to a dose of 3 mg/day, and biperidin was completely withdrawn. No further changes were made in Ms. A’s drug regimen, because her condition was considered satisfactory. Four months after discharge, Ms. A’s clinical condition has remained stable.