Patients with schizophrenia have decreased chronnectomic density in the dorsolateral prefrontal cortex, compared with healthy controls, and cigarette smoking in patients with schizophrenia may be associated with a degree of preserved function in that brain region, researchers reported. The results indicate that smoking may be associated with a preservation effect, but it “cannot restore patients’ prefrontal dysfunction to normal levels,” the researchers said.
Thedepicts how brain functional connectivity patterns (i.e., the connectome) vary over time. “Therefore, the chronnectome may be an effective index to evaluate the smoking-related prefrontal functional changes in schizophrenia,” said Yun-Shuang Fan, a researcher at the Clinical Hospital of Chengdu Brain Science Institute in China, and colleagues in the , which was published in Progress in Neuro-Psychopharmacology & Biological Psychiatry.
The investigators studied 49 patients with schizophrenia, including 22 smokers and 27 nonsmokers, and 43 healthy controls, including 22 smokers and 21 nonsmokers. Participants underwent resting-state functional magnetic resonance imaging, and the researchers analyzed chronnectomic density using a sliding-window method. The investigators examined interactions between smoking status and diagnosis.
Smoking was associated with reduced chronnectomic density in healthy controls, but increased density in patients with schizophrenia. The study provides a “framework to elaborate upon the self-medication hypothesis in schizophrenia” and sheds “some fresh light on the elevated rates of smoking in schizophrenia,” they said.
The study was relatively small, and patients’ use of antipsychotic medications, which can affect the connectome, may limit the results. In addition, the study’s cross-sectional design precludes knowing whether “smoking behavior is the cause or result of the prefrontal chronnectome alterations in schizophrenia,” the authors added.
The study was supported by the National Natural Science Foundation of China and the Sichuan Science and Technology Program. The researchers had no conflicts of interest.
SOURCE: Fan YS et al. Prog Neuropsychopharmacol Biol Psychiatry. 2020 Apr 20. doi: 10.1016/j.pnpbp.2020.109860.