Therapeutic target for cognition enhancers: diagnosis and clinical phenomenology.

Uncertainty concerning therapeutic targets has probably retarded the development of cognition-enhancing drugs. While enhancement of normal cognitive function may be a legitimate goal it is unlikely that drugs developed without a clear clinical indication will ever be approved by regulatory authorities. Normal aging as a target would also appear to be excluded. The main debate is whether drugs should be developed for specific disease states (e.g., Alzheimer's), particular syndromes (e.g., AAMI) or for treating symptoms (e.g., memory deficits). Although targeting disease states appears the least problematic, it would be difficult to include many potentially treatable patients in such studies. In this respect, the status of AAMI is still the subject of much debate. In any case, it is important that trial populations be as homogeneous as possible, with clear diagnostic criteria (e.g., defined memory impairment, Hachinski score, CT scans) and that patients be moderately to severely affected.