Recent work by Howes and colleagues found that in the earliest stages of schizophrenia, people experience a surge in the number and activity of immune cells in the brain. As well as fighting infection, these cells, called microglia, have a “gardening” role, pruning unwanted connections between neurons. But in schizophrenia patients, the pruning appears to become more aggressive, leading to vital connections being lost.
“We studied people in that [initial] phase of the illness and saw microglial changes,” said Howes. “It shows that it’s something [happening] very early on and seems to be driving the illness.”
The most extensive pruning appears to occur in the frontal cortex, the brain’s master control centre, and also the auditory regions, which could explain why patients often hear voices. The frontal cortex indirectly controls the brain’s levels of dopamine – a surge in this brain chemical is thought to explain the delusions and paranoia experienced by those with schizophrenia.
