Serotonin receptors represent highly favorable molecular targets for cognitive enhancement in schizophrenia and other disorders.
BACKGROUND
Current treatments for schizophrenia adequately treat the positive symptoms of schizophrenia but only modestly improve cognitive deficits. This review provides evidence for and against the use of selective 5-HT receptor drugs as cognition enhancing agents for schizophrenia and other disorders.


METHODS
Pre-clinical and clinical literature concerned with the role of the serotonergic system in cognition and memory as it relates to schizophrenia is reviewed. Individual 5-HT receptor subtypes for which selective drugs are available that are likely to improve cognition are reviewed. Recommendations for clinical testing are proposed.


CONCLUSIONS
Four 5-HT receptor systems (5-HT(1A), 5-HT(2A), 5-HT(4), 5-HT(6)) are highlighted as suitable targets for enhancing cognition and memory. Because many clinically available antipsychotic drugs already target 5-HT(1A), 5-HT(2A) and 5-HT(6) receptors, design of clinical trials will need to take into account the serotonergic pharmacology of concurrently administered antipsychotic medications. 5-HT(1A) partial agonists and 5-HT(2A) antagonists have shown modest effectiveness in improving cognition in schizophrenia. 5-HT(6)-selective compounds for cognition enhancement are in late-stage clinical trials, while 5-HT(4) compounds have not yet been tested in humans for cognition enhancement.


CONCLUSIONS
For stand-alone therapy for enhancing cognition, 5-HT(1A) partial agonists, 5-HT(2A) antagonists, 5-HT(4) partial agonists and 5-HT(6) antagonists are all likely to induce at least modest improvement in cognition in schizophrenia. If "add-on therapy" is contemplated, antipsychotic drugs with weak affinities for serotonin receptors should be used to avoid confounds. It is likely that serotonergic drugs will soon be available as cognition enhancing medications for disorders other than schizophrenia (e.g. dementia).
Roth
Bryan L
BL
Department of Biochemistry, and NIMH Psychoactive Drug Screening Program, Case Western Reserve University Medical School, 2109 Adelbert Road, Cleveland, OH 44106, USA. bryan.roth@case.edu
Hanizavareh
S Mohammad
SM
Blum
Andrew E
AE
D000818:Animals; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D003071:Cognition / Q000187:drug effects*; D006801:Humans; D008568:Memory / Q000187:drug effects; D011985:Receptors, Serotonin / Q000145:classification / Q000502:physiology*; D012559:Schizophrenia / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D018490:Serotonin Agents / Q000627:therapeutic use*
D014150:Antipsychotic Agents; D011985:Receptors, Serotonin; D018490:Serotonin Agents