Treatment of Bipolar Depression, and Micro Changes in the Structure of Gray Matter

Diffusion tensor imaging (DTI) is one of the most commonly used non-invasive methods being used to determine the integrity of the white matter. DTI measurements give rise to the thoughts that there is a prevalent change in the micro structure of the gray matter in patients with bipolar disorder (BD). A chronotherapeutic combination of total sleep deprivation (TSD) and light therapy (LT) can acutely reverse depressive symptoms in nearly 60% of the patients. Moreover, it was approved as a model antidepressant treatment to research the neurobiological correlations of the fast antidepressant response.

In order to test whether the changes in the DTI measurements of the micro structure of BD were in parallel with the antidepressant response, 44 patients, who were in the major depressive episode of bipolar disorder, were treated with chronotherapeutics for a week.

Fractional anisotropy (FA) is known to be susceptible to the structural changes in myelination, axonal density, axonal caliber and fiber coherence. When compared to the initial level, no significant increase was observed in the measurement of mean fractional anisotropy (FA) for a week of follow-up, and concordantly, a significant reduction was observed in the mean diffusion value (DV) of various white matter (WM) pathways, including cingulum, corpus callosum, corona radiata, corticospinal system, internal capsule, fornix and uncinate fasciculus. The degree of change was found to be associated with the clinical response.

The results of the study provide evidences that increase the role of the chronotherapeutics in primary care for depression. Moreover, they also make contributions to the determination of the neuroimaging-based biomarkers of the antidepressant response.

REFERENCES:
Melloni, E. M. T., Poletti, S., Dallaspezia, S., Bollettini, I., Vai, B., Barbini, B., … Benedetti, F. (2020). Changes of white matter microstructure after successful treatment of bipolar depression. Journal of Affective Disorders. doi:10.1016/j.jad.2020.05.146
https://dergipark.org.tr/en/pub/pgy/issue/26726/281382

ABBREVIATIONS:
DTI: Diffusion tensor imaging is an imaging method that provides pure diffusion images by eliminating the direction-dependent effects of the diffusion.
TSD: Total sleep deprivation
LT: Light therapy