This gray matter reduction does not seem to be related to neuronal loss occurring after the second trimester. Indeed, only a few studies have found evidence for gliosis, a reputedly robust marker of neuronal necrosis, in the brains of patients with schizophrenia.8,9 It might be possible that some neurons are lost by apoptosis not necessarily accompanied by gliosis, but the general consensus is that most gray matter atrophy represents a reduction in neuronal volume.10 As a matter of fact, cortical neurons are generally described as being smaller with higher density in pathological studies. Many authors have pointed out that the compartment showing the larger reduction could be the volume of axons and dendrites. In other words, there should be a reduction in the connecting parts of the neurons. In line with these arguments, synaptic spines and synaptic markers are reduced,11 as well as synaptic gene expression.12
