Smart Drugs Are Poor Cognitive Enhancers

In recent years, there has been an increase in the use of prescription stimulant drugs by students and employees to enhance academic and other work productivity. Despite the recognition that these drugs enhance cognitive function in individuals, the available evidence is inconclusive. Cognitive enhancement is usually seen only in clinical populations, not in the general population. Interestingly, even in the clinical population, improvement in cognitive impairment was modest. Therefore, there is a need to evaluate the efficacy of these agents in real-world situations.

study: Not very smart? ‘Smart’ Drugs Increase Levels of Cognitive Effort, But Decrease Quality. Image credit: Victor Moussa / Shutterstock

Background

Many everyday tasks can be categorized as mathematically “hard” problems. These problems usually belong to the nondeterministic polynomial (NP) hard complexity class. These tasks require systematic approaches (algorithms) to achieve optimal results. For very complex problems (such as how many ways to repair a product or how many stops to make along the way), more computation is required and quickly exceeds cognitive capacity.

Recent scientific progress In this study, we focus on the real-world everyday difficulty, namely the 0-1 knapsack optimization problem (the “knapsack” task”). Knapsack tasks are essentially combinatorial optimization tasks, a class of NP-time hard problems.

MPH and DEX are catecholaminergic agents associated with enhanced dopaminergic activity in cortical and subcortical regions. They also exhibit noradrenergic activity. However, MPH is an inhibitor of dopamine and noradrenaline transporters.

About research

A total of 40 healthy individuals were recruited into a double-blind, placebo (PLC)-controlled, single-dose study. This cohort included 17 males and 23 females aged 18 to 35 years. All participants underwent a semi-structured interview and exam prior to enrollment. Volunteers with a history of heart disease, psychotropic medication, neurological disease (such as epilepsy) or psychiatric disease, or pregnancy were excluded from the cohort.

Participants were required to attend 4 test sessions, with each session separated by a minimum of 7 days. At each session, participants received either MOD 200mg, MPH 30mg, DEX 15mg, or PLC.

Here, participants were randomly assigned to four groups. Each group was provided different sequences of medications and PLCs throughout the sessions, according to a balanced Latin square design. During the knapsack task, each participant was presented with several items associated with weight and value.

Participants were presented with eight unique instances of the knapsack task via the user interface. Some examples were less taxing on working memory and arithmetic, while others were purely numeric (more complex). The participant tried each instance on her two occasions. For each answer he was allotted a time limit of 4 minutes. To analyze the compatibility of study results with previous experiments, participants were asked to complete four tasks from the CANTAB cognitive battery.

research result

Even though the medication did not significantly reduce the likelihood of solving the knapsack problem, it did cause a significant reduction in the overall value achieved. Participants who received smart drugs had, on average, significantly improved time spent or effort levels. However, we observed heterogeneity in the quality of effort associated with each drug compared to PLC. Quality of effort was described as improvement in knapsack value per move.

Interestingly, if individuals undergoing PLC showed significant increases in knapsack values ​​with each move, those same individuals tended to be below average under smart drag. Similarly, individuals who performed below average on PLC also had above average quality of effort on smart drugs. This reversal in quality of effort may be due to participants’ selection being found to be more erratic under smart drugs.

All tasks were computationally intensive and required systematic thinking to handle. The task is designed so that random exploration is ineffective. Proper effort distribution is important for knapsack tasks. Smart drugs increase subjective reward while reducing perceived effort.These drugs adversely affect efficacy.

All three smart drugs reduced participants’ performance on some of the CANTAB tasks included in this study. In this study, it was not possible to determine the effects of individual drugs in the knapsack task based on the CANTAB task values.

Conclusion

The current study has provided insight into how smart drugs affect the daily lives of patients suffering from conditions such as: attention deficit hyperactivity disorder (ADHD). It turns out that smart drugs only increase work motivation, not the quality of effort.