If you’ve ever gone to the grocery store but forgot your shopping list at home, you know just how frustrating it can be trying to remember what to buy. Now, science is revealing why your personality can influence how quickly and accurately you recall items on your list.

Memory has long been a major area of interest to neuroscientists, and previous work has demonstrated that different personality traits affect working memory. But scientists didn’t know just what was happening in the brain to link the two.

“Neuroticism is universally implicated in making things difficult for people, whatever they might be doing. These associations have been known, but there was no mechanism to say why one thing influenced the other,” says study leader Sophia Frangou at the Icahn School of Medicine at Mount Sinai in New York. The new work by Frangou and her colleagues in the United Kingdom and Switzerland explores the relationship between certain personalities and increased or decreased brain plasticity—the ability of the brain to change the strength of its neural connections based on cognitive demands.

The scientists measured the brain activity of 40 adult participants while they completed a working memory test. To scan the brain, the team used a tried and true neuroimaging technique—functional magnetic resonance imaging (fMRI)—with a relatively new method for interpreting the data called dynamic causal modeling.

“The advantage of dynamic causal modeling is that it moves away from globalness,” Frangou explains. “Instead of saying this lobe of the brain is bigger or brighter, it instead looks at what way one region of the brain influences this other brain region during a task.” In other words, the technique helps scientists better understand the connections being made in the brain.

The memory test asked study participants to view a sequence of letters on a computer screen and indicate when a current letter matched one from earlier steps in the sequence. Then the investigators evaluated participants’ personality traits using a well-known test in psychology called the NEO-PI-R, which measures the five major domains of personality: neuroticism, extraversion, openness to experience, agreeableness and conscientiousness. Two of these personality types were strongly linked to the level of efficiency at which individuals completed the memory task, the team reports this week in Human Brain Mapping.

“We found that people who are more neurotic, perhaps because they have the tendency to worry, were less efficient,” Frangou says. Meanwhile, subjects who scored higher on the conscientiousness scale, which is defined as having a measure of self-discipline, completed the task more quickly and with a higher accuracy rate.

The dynamic causal modeling helped illuminate why: People who did well on the task showed increased activity in the top part of their brains and made stronger neural connections, while the more neurotic individuals took longer to make the same brain connections.

If you’re a worrywart and prone to neurotic behavior, Frangou says you’re more likely to take a longer time at the grocery store trying to remember everything on your list. You might miss a few items, too. “But someone who is less prone to distress and is able to focus on the task at hand will be more likely to get everything on the list and do it more quickly,” Frangou says.

David Glahn, a professor of psychiatry at the Yale School of Medicine, says the team’s study is intriguing because it looks at the association between memory and personality at the microscale. “What they’re saying is not only is brain connectivity important to being able to serve working memory function, but it has a direct relationship to long-term, trait-like thinking patterns and behaviors,” Glahn says. The study also brings up the possibility of using similar brain connectivity models to learn more about personality disorders.

While the study only included 40 individuals, Glahn notes that the team found such strong links between neuroticism, conscientiousness and working memory that he thinks the results could have wide implications. “I believe this study will allow us to draw conclusions about the broader population, because the individuals in the study were not selected specifically because of their neuroticism scores. They were individuals with normal variations of neuroticism.” That said, Glahn would like to see the same methodology applied to people on the more extreme ends of the personality test, such as highly neurotic individuals who have trouble interacting in society.

Frangou and her team are now developing neuroscience-based talk therapies that target neuroticism with the aim of improving cognition. She adds that it is possible for neurotic individuals to improve their memory skills, but the latest study provides additional evidence that these people are more limited than other personality types in their capacity for working memory.