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Biol Psychiatry. 2020 Feb 1;87(3):271-281. doi: 10.1016/j.biopsych.2019.08.015. Epub 2019 Aug 29.

Longitudinal Cortical Thickness Changes in Bipolar Disorder and the Relationship to Genetic Risk, Mania, and Lithium Use.

Author information

1
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. Electronic address: christoph.abe@ki.se.
2
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
3
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
4
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
5
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the Gothenburg University, Gothenburg, Sweden; Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet and Stockholm County, Stockholm, Sweden.

Abstract

BACKGROUND:

Bipolar disorder (BD) is a highly heritable psychiatric disorder characterized by episodes of manic and depressed mood states and associated with cortical brain abnormalities. Although the course of BD is often progressive, longitudinal brain imaging studies are scarce. It remains unknown whether brain abnormalities are static traits of BD or result from pathological changes over time. Moreover, the genetic effect on implicated brain regions remains unknown.

METHODS:

Patients with BD and healthy control (HC) subjects underwent structural magnetic resonance imaging at baseline (123 patients, 83 HC subjects) and after 6 years (90 patients, 61 HC subjects). Cortical thickness maps were generated using FreeSurfer. Using linear mixed effects models, we compared longitudinal changes in cortical thickness between patients with BD and HC subjects across the whole brain. We related our findings to genetic risk for BD and tested for effects of demographic and clinical variables.

RESULTS:

Patients showed abnormal cortical thinning of temporal cortices and thickness increases in visual/somatosensory brain areas. Thickness increases were related to genetic risk and lithium use. Patients who experienced hypomanic or manic episodes between time points showed abnormal thinning in inferior frontal cortices. Cortical changes did not differ between diagnostic BD subtypes I and II.

CONCLUSIONS:

In the largest longitudinal BD study to date, we detected abnormal cortical changes with high anatomical resolution. We delineated regional effects of clinical symptoms, genetic factors, and medication that may explain progressive brain changes in BD. Our study yields important insights into disease mechanisms and suggests that neuroprogression plays a role in BD.

KEYWORDS:

Bipolar disorder; Cortical thickness; Lithium; Longitudinal study; Mania; Polygenic risk score

PMID:
31635761
DOI:
10.1016/j.biopsych.2019.08.015
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