Anticonvulsant drugs, behavior, and cognitive abilities.

The literature concerning the relationship of anticonvulsant drugs to disturbances of behavior and cognitive abilities has been reviewed. It is indicated that although completed studies are sparse and although many of the techniques currently used for evaluating the effects os such drugs on patients are inadequate, certain conclusions may be drawn. With regard to the effects on cognitive abilities, the drugs not only impair performance on psychological tests, but some drugs--particularly phenytoin--are associated with a progressive decline of intellectual abilities, which is often insidious and unrecognized. There is little systematic evidence to indicate which anticonvulsant drugs have adverse effects on behavior, but several studies have indicated improvements in behavior associated with carbamazepine and sulthiame. The possible reasons why anticonvulsant drugs should have those effects are discussed, and particularly the relationship of the drugs to abnormal folic acid and monoamine and metabolism are highlighted.