Lev Tolstoy was right. “All happy families are alike,” the famous novelist wrote in Anna Karenina. “Every unhappy family is unhappy in its own way.” Turns out, something similar happens to the brains of optimistic and pessimistic people.

When scientists peered into the minds of people imagining the future, they discovered that the brain activity of optimists looked strikingly similar to that of other optimists. The neural patterns of less optimistic people, however, were far more varied. This suggests that optimism may be a way to process information rather than a sunny disposition.

Your Brain on Optimism

In the study, a team of neuroscientists in Japan, led by Dr. Kuniaki Yanagisawa of Kobe University, asked dozens of volunteers to lie in a functional magnetic resonance imaging (fMRI) scanner. The fMRI measured brain activity by tracking changes in blood flow. While inside, the participants were asked to vividly imagine a series of future events, ranging from the pleasant to the profoundly negative. They imagined these events happening both to themselves and to their romantic partners. Participants also filled out questionnaires to gauge how optimistic or pessimistic they were.

The researchers focused on a brain region called the medial prefrontal cortex, or MPFC, which sits just behind the forehead. This area plays a role in various cognitive and emotional functions, including social interactions and understanding others’ mental states. It’s also a key hub of the brain’s “default mode network,” a system that becomes active when we let our minds wander, remember the past, or envision the future.

By comparing the complex patterns of activity in the MPFC from person to person, the scientists could see just how similarly or differently each individual’s brain represented these imagined futures. The results were clear and consistent across two separate studies. The higher a person scored on a standard questionnaire for optimism, the more their brain patterns in the MPFC resembled those of other optimists.

But the same didn’t happen for pessimists.

Pessimists tended to be much more unique in how they viewed unpleasant futures. They showcased a wider and more diverse range of brain activity.

“Optimistic individuals consistently exhibit convergent neural representations, reflecting shared patterns of episodic future thinking, whereas less optimistic individuals demonstrate increased variability,” the study reported. For pessimists, the results were “idiosyncratic.”

A Sharp Line Between Good and Bad

Optimism, it turned out, was directly linked to how sharply the brain distinguished between good and bad futures. In the minds of optimists, the neural signature for a positive event was very distinct from that of a negative one. Simply put, they process negative future scenarios in an abstract and psychologically distant manner, which helps to mitigate the emotional impact of such scenarios. However, they imagine positive events vividly and concretely.

Optimism is already linked to several positive outcomes, including having larger social networks and higher-quality relationships. This new research provides a potential neurological explanation for why that might be. Their brains are more in tune, which makes them more relatable to one another, smoothing the path for social bonding.

But this doesn’t necessarily mean that optimism is a good trait and pessimism is a bad one. Pessimism can be a useful trait in some situations, helping people better prepare for the future. Consequently, optimism can easily lead to overconfidence and negative results. Furthermore, optimism and pessimism aren’t unchanging traits. They’re shaped constantly throughout our lives, and they’re also different from culture to culture.

Understanding the Mind

Yanagisawa ultimately believes this work can help us better understand how people relate to each other, and furthermore, what sometimes prevents empathy.

“The everyday feeling of ‘being on the same wavelength’ is not just a metaphor. The brains of optimists may in a very physical sense share a common concept of the future. But this raises new questions. Is this shared mechanism something they are born with or is it woven in later, for example through experience and dialogue?”

Yanagisawa’s ultimate goal is to gain a deeper understanding of what causes loneliness and what enables people to communicate with each other. He says, “I believe that elucidating the process by which this shared reality emerges is a step towards a society where people can communicate better.”

Journal Reference: Kuniaki Yanagisawa, Ryusuke Nakai, Kohei Asano, Emiko S. Kashima, Hitomi Sugiura, Nobuhito Abe. Optimistic people are all alike: Shared neural representations supporting episodic future thinking among optimistic individuals. Proceedings of the National Academy of Sciences, 2025; 122 (30) DOI: 10.1073/pnas.2511101122