Long-term effects of using cognitive-enhancing drugs by healthy people need to be determined

The government, pharmaceutical industry, and national medical organisations need to work together to look at the harms and benefits of long-term use of cognitive-enhancing drugs by healthy individuals, say neuroscientists Professor Barbara Sahakian and Dr Sharon Morein-Zamir from the University of Cambridge in the UK, writing in a Personal View in The Lancet Psychiatry journal.

There is growing “lifestyle use” of cognitive-enhancing drugs – such as methylphenidate (marketed as Ritalin) and modafinil (marketed as Provigil) – by healthy individuals to improve concentration, memory, and other aspects of cognitive performance. But very little is known about the long-term effects of this non-medical use, say the authors. “We simply do not know enough about how many healthy people are using cognitive-enhancing drugs, in what ways and why,”, explains Professor Sahakian.

What evidence there is suggests that healthy individuals use cognitive-enhancing drugs to gain a competitive edge at school, university, or work, and for maintaining attention and performance when sleep derived or jet lagged. Most research has focused on student use in the USA with estimates varying between 5% and 35%. Worryingly, say the authors, this might only be the tip of the iceberg and is unlikely to be representative of usage in professional or older populations.

A wide range of pharmaceutical substances from psychotropic medications to nicotine and caffeine are used by patients and healthy individuals to alter, improve, and enhance mental functioning. Most cognitive enhancers, such as modafinil and donepezil, have been developed by the pharmaceutical industry to treat the effects of impaired cognition in conditions such as Alzheimer’s disease, attention deficit hyperactivity disorder (ADHD), and schizophrenia. For example, even after the remission of psychosis in schizophrenia, full functional recovery (eg, returning to work and independent living) is limited by debilitating cognitive symptoms.

But non-medical use raises a host of safety and ethical concerns including side effects and potential abuse, particularly from sourcing on the internet. “Present cognitive-enhancing drugs have wide ranging effects and side effects and are not predictable. We also know next to nothing about their long-terms effects in healthy people”, says Dr Morein-Zamir.

The authors believe that the use and number of cognitive-enhancing drugs is likely to grow substantially and call on funders and policy-makers to prioritise research into the potential advantages and dangers of their use in healthy individuals, saying that, “reliable evidence is crucial for a balanced view on the risks and benefits of these drugs and to set out clear regulatory guidelines for their use.”

Cognitive-enhancing drugs are often viewed as a single class despite having distinct pharmacological mechanisms, effects, and legal status. Therefore, a case-by-case discussion of regulation is needed, say the authors, considering the potential for physical and psychological dependence as well as social harms.

According to Professor Sahakian and Dr Morein-Zamir, while there is “great merit” in the development of new more effective and safer cognitive enhancers, the growing off-label use of drugs such as Ritalin (methylphenidate; prescribed for ADHD) and Provigil (modafinil; prescribed for sleep disorders) demands that clear information and guidelines about their benefits, risks, and safety be made available to all health-care professional by national medical organisations.