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Quantification of brain proton longitudinal relaxation (T 1 ) in lithium‐treated and lithium‐naïve patients with bipolar disorder in comparison to healthy controls
Author(s) -
Necus Joe,
Smith Fiona Elizabeth,
Thelwall Peter Edward,
Flowers Carly Jay,
Sinha Nishant,
Taylor Peter Neal,
Blamire Andrew Matthew,
Wang Yujiang,
Cousins David Andrew
Publication year - 2021
Publication title -
bipolar disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.285
H-Index - 129
eISSN - 1399-5618
pISSN - 1398-5647
DOI - 10.1111/bdi.12878
Subject(s) - bipolar disorder , lithium (medication) , white matter , psychology , medicine , cardiology , neuroscience , nuclear medicine , gastroenterology , nuclear magnetic resonance , magnetic resonance imaging , radiology , physics
Background Proton longitudinal relaxation (T 1 ) is a quantitative MRI‐derived tissue parameter sensitive to myelin, macromolecular, iron and water content. There is some evidence to suggest that cortical T 1 is elevated in bipolar disorder and that lithium administration reduces cortical T 1 . However, T 1 has not yet been quantified in separate groups containing lithium‐treated patients, lithium‐naïve patients, and matched healthy controls. Methods Euthymic patients with bipolar disorder receiving lithium (n = 18, BDL) and those on other medications but naïve to lithium (n = 20, BDC) underwent quantitative T 1 mapping alongside healthy controls (n = 18, HC). T 1 was compared between groups within the cortex, white matter and subcortical structures using regions of interest (ROI) derived from the Desikan‐Killiany atlas. Effect sizes for each ROI were computed for BDC vs BDL groups and Bipolar Disorder vs HC groups. Results No significant differences in T 1 were identified between BDL and BDC groups when corrected for multiple comparisons. Patients with bipolar disorder had significantly higher mean T 1 in a range of ROIs compared to healthy controls, including bilateral motor, somatosensory and superior temporal regions, subcortical structures and white matter. Conclusions The higher T 1 values observed in the patients with bipolar disorder may reflect abnormal tissue microstructure. Whilst the precise mechanism remains unknown, these findings may have a basis in differences in myelination, macromolecular content, iron and water content between patients and controls.