Cognitive enhancers-truth vs. hype

Cognition is a term referring to the mental processes involved in gaining knowledge and comprehension. It is a higher-level function of the brain and encompasses language, imagination, perception, and planning. Cognitive enhancers are neuro-active substances that elevate individual's cognitive abilities in a meaningful & sustained way. Many groups of drugs have been used as cognitive enhancers or nootropics- be it racetams like piracetam, cholinergics like citicoline, acetylcholinesterase inhibitors like rivastagmine, AMPAkines like memantine or smart drugs like modafinil and methylphenidate. Glutaminergic input activates AMPA receptors resulting in depolarization that opens NMDA receptors of the NR2A subtype. This promotes calcium ion entry into neurons thereby causing membrane potentiation that helps in learning and cognition. Cognitive enhancement can either happen by increasing blood flow to the brain, enhancing neurotransmission, increased neuronal metabolism by stimulation of hormones and enzymes, increased nerve growth factor and improvement of cerebral functions like memory. However, it is difficult to attribute a specific mechanism of action to a particular drug or neurotransmitter. Nootropics have been used for a wide array of conditions ranging from developmental conditions like Attention Deficit Hyperkinetic Disorder (ADHD) to neurodegenerative conditions like Alzheimer's disease and Parkinson's disease. However, in the recent past there has been a sudden surge in the use of these cognitive enhancers in normal, healthy individuals as well. Cognitive enhancers have proved quite an asset when it comes to slowing down the disease progression. However, in the healthy population there is a dearth of literature regarding their long term safety and efficacy. Ethical issues are also a matter of concern.