How realistic are the scientific assumptions of the neuroenhancement debate? Assessing the pharmacological optimism and neuroenhancement prevalence hypotheses - Schleim & Quednow - 2018 - Article

This article focuses on the issue of neuroenhancement – the improvement of healthy people’s cognitive functioning on a neural level, through usage of stimulant drugs. The idea that intellectual performance can be improved by drugs is called the “pharmacological optimism hypothesis", whereas the notion that pharmacological neuroenhancement is used commonly is called the “neuroenhancement prevalence hypothesis''. 

The paper starts off by discussing the pharmacological hypothesis. The failure to discover a reliable biomarker for any of the hundreds of DSM-5 classifications lead to the introduction of a new research paradigm, the Research Domain Criteria (RDoC), whose scientific advantage remains unclear. Neuroenhancement literature was optimistic that new drugs for dementia or attention disorders could be used for improving cognitive functioning in healthy people. Despite of these hopes, the funding crisis of psychopharmacology became evident. The neuroenhancement literature covers well-known stimulant drugs - amphetamine, methylphenidate and modafinil. These drugs are still prescribed for some psychiatric conditions. However, just because the molecules have been investigated for a long time does not mean that they do not pose scientific challenges. The ethical issue of intervening in brain chemistry is disputable in healthy people. Most of the thus far tested substances have very limited effects on disturbed cognitive functions in psychiatric patient populations. The evidence is still low that so far discussed drugs broadly enhance cognitive performance in healthy people - we have to reject the pharmacological optimism hypothesis for now. 

The paper ends with the discussion of the neuroenhancement prevalence hypothesis. It is debatable how high the percentage of consumers needs to be to speak of a “common” or “epidemic” use. However, there is currently no evidence that the numbers have really been increasing in the past 20 years. Many of the consumers responding positively in the surveys are young people trying out prescription stimulants for neuroenhancement or occassional recreational use. Due to those reasons, the authors reject the neuroenhancement prevalence hypothesis for now.