Abstracts

New onset psychosis has been reported in epileptics on topiramate (TOP). The incidence is from 0.8% in clinical trials to 12% in one large series. Some reports include epileptics with developmental disabilities.Prevalence of psychosis in epileptics is reported as 2.6%, cumulative incidence 10.3%. In epileptics with profound mental retardation (DD/MR) incidence of a single psychiatric diagnosis ranges from 3.9% to 22.1% for severe behavior problems, with psychosis varying depending on diagnostic criteria.
TOP potentiates GABAergic neurotransmission and antagonizes excitotoxic actions of glutamate at the (AMPA)/kainite glutamate-gated channels. These are two predicted consequences of NMDA receptor hypofunction. A model of schizophrenia suggests NMDA receptor hypofunction plays a role in the pathophysiology of psychosis.
TOP is prescribed for various epilepsies in DD/MR. If incidence of psychosis increases in those DD/MR epileptics given TOP, a relationship may be discerned.
A retrospective chart review of patients (N=88) treated with TOP. Pharmacy data identifies patients on AEDs and neuroleptics. FH of psychiatric disease and behavioral scales are examined.
Neuroleptic use at this center is 31.6% of all residents. Neuroleptic use for residents treated with TOP for seizures is 12%. Of those treated with TOP + neuroleptic, more than 90% needed neuroleptics prior to TOP exposure. There were no hospitalizations for psychosis. Increased aggressive behavior is rare and discussed.
This data does not support the idea that profound mental retardation is a risk factor for TOP related psychosis. While subtle psychotic symptoms are not easily assessed in this population, behavioral changes and aggression are rated. Lack of correlation may be due to small sample size, lower doses of TOP (250 mg/day) and slow increases of dosage.As TOP is used for bipolar disorder, headache, and weight reduction (particularly for those with neuroleptic-induced obesity) it is important to screen for early signs of psychosis and develop useful risk factors to identify those most vulnerable.
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