Cigarette smoking is associated with thinner cingulate and insular cortices in patients with severe mental illness

• Published in: Journal of psychiatry & neuroscience 2015-07, Vol.40 (4), p.241-249
• Main Authors: Jørgensen, Kjetil Nordbø, MPhil, Skjærvø, Ingeborg, MD, PhD, Mørch-Johnsen, Lynn, MD, Haukvik, Unn Kristin, MD, PhD, Lange, Elisabeth Heffermehl, MD, PhD, Agartz, Ingrid, Melle, Ingrid, MD, PhD, Andreassen, Ole Andreas, Psychol, Cand, MD
• Format: Article
• Language: English
• Subjects: Adult; Aging - pathology; Alcohol; Anniversaries; Bipolar disorder; Bipolar Disorder - complications; Bipolar Disorder - pathology; Brain research; Cerebral Cortex - pathology; Cigarettes; Cingulate cortex; Complications and side effects; Drug use; Female; Health aspects; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Medical Education; Mental disorders; Mentally ill; Organ Size; Patients; Physiological aspects; Psychiatric Status Rating Scales; Psychiatry; Psychosis; Psychotic Disorders - complications; Psychotic Disorders - pathology; Regions; Research Paper; Schizophrenia; Schizophrenia - complications; Schizophrenia - pathology; Severity of Illness Index; Smoking; Smoking - pathology; Tobacco Use Disorder - complications; Tobacco Use Disorder - pathology
• ISSN: 1180-4882; 1488-2434
• DOI: 10.1503/jpn.140163

Background Magnetic resonance imaging (MRI) studies show reduced cortical thickness in patients with schizophrenia and bipolar disorder. These subtle brain abnormalities may provide insight into illness mechanisms. However, environmental and lifestyle-related factors, such as cigarette smoking, may contribute to brain structure changes. Cigarette smoking is highly prevalent in patients with severe mental illness. In nonpsychiatric samples, smoking has been associated with reduced thickness in the anterior (ACC) and posterior cingulate cortices, the insular cortex (INS), the dorsolateral prefrontal cortex and the orbitofrontal cortex. Methods We examined MRI scans from patients with schizophrenia, other psychotic disorders or bipolar disorder and healthy controls using FreeSurfer. Results We included 506 patients (49% smokers) and 237 controls (20% smokers) in our study. We found reduced cortical thickness in the left rostral ACC and the left INS in smoking patients compared with nonsmoking patients, but this difference was not found among healthy controls. No dose–response relationship was found between amount of smoking and cortical thickness in these regions. Among patients, maps of thickness along the whole cortical surface revealed reduced insular thickness but no effects in other regions. Among healthy controls, similar analyses revealed increased age-related cortical thinning in the left occipital lobe among smokers compared with nonsmokers. Limitations The causal direction could not be determined owing to the cross-sectional design and lack of detailed data on smoking addiction and smoking history. Conclusion The effect of cigarette smoking should be considered in MRI studies of patients with severe mental illness.