In patients with depression, increases in cortical thickness have been observed following the use of electroconvulsive therapy (ECT), but these increases are transient. A longitudinal magnetic resonance (MRI) study (ClinicalTrials.gov identifier: NCT03040388) on the subject was conducted in Denmark, with the results published in the journal Acta Psychiatrica Scandinavica.
The investigators sought to describe changes in cortical thickness of the entire cortex both immediately after and 6 months following a series of ECT sessions compared with baseline measurements — the primary aim of the current study. The secondary aim was to examine whether these changes are associated with either the antidepressant effect of the treatment or with cognitive impairment. With the use of a 3 Tesla MRI scanner, they obtained T1-weighted brain images from 18 severely depressed patients at three separate time points: before, immediately after, and six months following a series of ECT sessions. They determined the thickness of 68 cortical regions via the utilization of Free Surfer. A Linear Mixed Model was used to assess the longitudinal changes.
Immediately following a series of ECT sessions, significant increases were observed in the cortical thickness of 26 regions, primarily within the frontal, temporal, and insular cortex. At six-month follow-up, however, this thickness returned to baseline values. There were no significant decreases observed in cortical thickness. The increase in the thickness of the right lateral orbitofrontal cortex was linked to a significantly greater antidepressant effect (P =.0005). In addition, none of the cortical regions demonstrated any relationships with cognitive adverse events.
A major limitation of the present study is the fact that because of the small sample size, potential important effects of ECT may have gone unrecognized. Moreover, the lack of a control group makes it difficult to differentiate the effect of ECT from the effects of time, medication, and depression.
The investigators concluded that additional multimodal MRI studies are warranted in order to evaluate the neural correlates of these increases in cortical thickness and their relationship with the antidepressant effect.
Gbyl K, Rostrup E, Raghava JM, et al. Cortical thickness following electroconvulsive therapy in patients with depression – a longitudinal MRI study [published online July 2, 2019]. Acta Psychiatr Scand. doi:10.1111/acps.13068