Participants with more attention lapses liked a 20-mg d-amphetamine dose less than those with fewer lapses in one healthy-volunteer study. This finding runs against a simple assumption that worse attention necessarily predicts stronger subjective stimulant reward.
McCloskey, Palmer and de Wit divided 99 healthy volunteers into three equal groups based on a reaction-time measure of attention lapses. Participants were compared on ratings after placebo and 5-, 10- and 20-mg d-amphetamine conditions.
The grouping measure concerned unusually long reaction times. It was a behavioral index of inattention, not a diagnosis of ADHD or a toxicology test.
The high-lapse group reported less liking after 20 mg than the low-lapse group. A smaller increase in wanting more drug was described as a tendency. That tendency should not be presented as a statistically established effect equivalent to the liking comparison.
The result also should remain attached to the dose at which it was demonstrated. It does not establish that the same group pattern occurs at every dose or under other routes of administration.
The paper investigated a relationship between an attention measure and subjective response. It did not establish that participants with greater liking obtained larger cognitive benefits or that those with less liking were more impaired.
A rating of wanting more drug is also different from actually working for a dose, repeated use outside the laboratory or developing dependence.
The association suggests that attention and reward sensitivity deserve separate investigation. Healthy-volunteer selection, grouping decisions and the limited range of doses constrain generalization.
The paper cannot determine whether a person’s inattention caused a particular drug preference or predict that person’s future substance use. It likewise cannot identify an impairment threshold. Its useful message is that cognitive difficulty and subjective reward do not necessarily vary in the intuitive direction or represent the same underlying process.
Related reading: Why faster responses can accompany more errors.