title: Selective phosphodiesterase inhibitors: a promising target for cognition enhancement.
abstract: BACKGROUND
  One of the major complaints most people face during aging is an impairment in cognitive functioning. This has a negative impact on the quality of daily life and is even more prominent in patients suffering from neurodegenerative and psychiatric disorders including Alzheimer's disease, schizophrenia, and depression. So far, the majority of cognition enhancers are generally targeting one particular neurotransmitter system. However, recently phosphodiesterases (PDEs) have gained increased attention as a potential new target for cognition enhancement. Inhibition of PDEs increases the intracellular availability of the second messengers cGMP and/or cAMP.
  
  
  OBJECTIVE
  The aim of this review was to provide an overview of the effects of phosphodiesterase inhibitors (PDE-Is) on cognition, the possible underlying mechanisms, and the relationship to current theories about memory formation.
  
  
  METHODS
  Studies of the effects of inhibitors of different PDE families (2, 4, 5, 9, and 10) on cognition were reviewed. In addition, studies related to PDE-Is and blood flow, emotional arousal, and long-term potentiation (LTP) were described.
  
  
  RESULTS
  PDE-Is have a positive effect on several aspects of cognition, including information processing, attention, memory, and executive functioning. At present, these data are likely to be explained in terms of an LTP-related mechanism of action.
  
  
  CONCLUSIONS
  PDE-Is are a promising target for cognition enhancement; the most suitable candidates appear to be PDE2-Is or PDE9-Is. The future for PDE-Is as cognition enhancers lies in the development of isoform-specific PDE-Is that have limited aversive side effects.
authors: Department of Neuroscience, Faculty of Health, Medicine and Life Sciences, School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands. o.reneerkens@np.unimaas.nl
authors: Olga A H
authors: OA
authors: Reneerkens
authors: Kris
authors: K
authors: Rutten
authors: Harry W M
authors: HW
authors: Steinbusch
authors: Arjan
authors: A
authors: Blokland
authors: Jos
authors: J
authors: Prickaerts
mesh_terms: D000818:Animals; D003071:Cognition / Q000187:drug effects*; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D008568:Memory / Q000187:drug effects; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism / Q000502:physiology*; D015290:Second Messenger Systems / Q000187:drug effects
chemical_list: D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D010727:Phosphoric Diester Hydrolases