How depression makes people vulnerable to misinformation

For years, scientists have been trying to understand what makes a person prone to believing in dangerous conspiracy theories. It’s never been more important: as the pandemic bears on, misinformation is driving people to avoid potentially life-saving vaccines or treatments, and has cleft huge rifts in the fabric of society, alienating people from family, friends and community.

Now, a US study has found that people suffering from depression are much more likely to believe misinformation about COVID-19 vaccines. That means misinformation is most effective when targeted at vulnerable people – a common tactic used by conspiracy theorists and political subcultures.

The study, published in JAMA, surveyed more than 15,000 US adults across the nation’s 50 states. The researchers measured depressive symptoms against a person’s likelihood to agree with at least one of four false statements about COVID-19 vaccines.

They found that nearly 30% of people with depression were prone to believing misinformation, compared with around 15% of people without it. Respondents who believed at least one of the four misleading statements were also much less likely to be vaccinated. Finally, the team asked 2,809 of the survey respondents to answer a subsequent survey one to two months later; they found that people who reported depressive symptoms in the first survey were more likely to endorse misinformation months later.

Even when the results were adjusted for factors like political affiliation, socioeconomic status and self-reported ideology (a person’s individual set of beliefs), the connection stood up. 

The results matter: if almost a third of all Americans with depression are vulnerable to vaccine misinformation, that means they’re more likely to resist vaccination and other public health advice, putting them at higher risk of serious illness and death. And mood disorders are already known to be associated with worse COVID-19 outcomes in hospital.

So, why does depression make a person more vulnerable to misinformation? 

The researchers think it has to do with negativity bias. This is the tendency to focus more on negative information than positive information, an evolutionary quirk of our species that keeps us constantly aware of danger, and which would have served us well in the threat-laden plains of our evolutionary past.

But while negativity bias is present in all of us, “individuals with major depressive symptoms often exhibit a more pronounced negativity bias,” write the authors. This tendency to focus on the negative can make people cynical about the status quo, suspicious of authority, and ultimately cause them to underestimate – or simply not believe – the benefits of vaccinations.