The Brains of Delusional People Function Quite Differently

Delusions are false beliefs that are held with certainty and are resistant to contradictory evidence. The human brain appears to easily embrace false beliefs and act as though they are true. Conspiracy theorists enjoy talking about the suspicious role of the CIA in Kennedy’s assassination, aliens at Area 51, and the claims by some conservatives that former President Donald Trump won the last election. Neuroscientists are fascinated by the resilience of this brain proclivity.

One study of the resilience of delusions was performed in 1959. Psychologist Milton Rokeach brought together three male schizophrenic patients who all identified as Christ. They lived together for two years in the Ypsilanti State Hospital. At first, the patients got along well, but then, their conversations turned to the issue of who is Christ. They argued extensively. “You oughta worship me, I’ll tell you that!” one of the Christs yelled. “I will not worship you! You’re a creature!” At the end of the experiment, they each were convinced that the other two were mentally ill and that they were the true Jesus. Today’s political discourse exhibits similar features.

The Experience of Delusions
The delusions of these three schizophrenics, like today’s conspiracy theorists, were assigned certainty and were intolerant to any scrutiny that might give rise to doubt, even when confronted with the weakness of their evidence. A recent study used functional magnetic resonance imaging (fMRI) to identify the brain network(s) involved in gathering information under conditions of weak evidence. The study compared people with schizophrenia experiencing delusions as compared with people with schizophrenia not experiencing delusions, as well as healthy controls. The healthy controls and patients not experiencing delusions strongly activated a brain network involved in visual attention; patients with delusional beliefs showed no increased activity in this network. Essentially, delusional thinking manifests as reduced information analysis during the early stages of visual information processing whereby weak evidence is incorrectly stamped as conclusive.

Today, almost two thousand different religions are practiced by humans. Religious beliefs are a form of extremely resistant personal delusions that are held with certainty and are resilient to contradictory evidence. A recent study investigated which resting-state brain circuits are utilized by religious non-believers, as compared to religious believers. Previous studies have demonstrated that a resting-state analysis is objective, stable, and capable of revealing individual differences in how the brain functions. Essentially, the analysis provides a kind of neural fingerprint of which brain regions are involved in the processing of emotions, memories, and thoughts.

Heuristic or Analytic Reasoning
The believers self-identified as Christian, Jewish, Muslim, Buddhist, or Hindu. The non-believers self-identified as atheists or agnostics. The believers and non-believers did not significantly differ with regard to gender (only slightly more were female), standard markers of intelligence, social status, a predisposition towards anxiousness, or emotional instability. The study concluded that not believing in a deity is due to the activation of distinct higher-order brain networks. The results demonstrated that religious believers are more likely to use more intuitive and heuristic reasoning and that religious non-believers are more likely to use more deliberate and analytic reasoning. For example, non-believers are more likely to process sensory information, particularly visual information, in a more deliberative manner that involves higher cortical areas, called top-down processing, involved in reasoning.

In contrast, religious believers are more likely to interpret visual information in a more emotional or intuitive manner, called bottom-up processing, which involves more ancient brain systems. Religious believers share this bottom-up processing bias with people who believe in supernatural or paranormal activity, such as telekinesis or clairvoyance.

Delusions may not always indicate a severe mental illness, sometimes they are just evidence of variations in the inherited brain circuitry of people who easily embrace wildly improbable beliefs that are powerfully held despite incontrovertible counterevidence.