Relationship between plasma clozapine/N-desmethylclozapine and changes in basal forebrain-dorsolateral prefrontal cortex coupling in treatment-resistant schizophrenia

Resting-state functional MRI in treatment-resistant schizophrenia

“…The cross-sectional CLZ study by Ganella et al ( 2017 ) described with the same TRS and HC cohorts as Ganella et al ( 2018 ) where an additional cohort of 16 unaffected family members (UFM) was investigated. Blazer et al ( 2022 ) presented the data of three additional participants compared to Sarpal et al ( 2022a ) in their longitudinal CLZ study. The study on ECT by Huang et al ( 2018 ), Jiang et al ( 2019a , b ), Wang et al ( 2020 ), Hu H. et al ( 2022 ), and Hu Q. et al ( 2022 ) reported on exactly the same patient cohort of 21 TRS individuals receiving a regular course of modified ECT combined with antipsychotics (MSZ), 21 SCZ individuals taking only antipsychotics (DSZ), and 23 HC, although one of the mentioned studies (Hu H. et al, 2022 ) listed (likely by mistake) different age characteristics for DSZ.…”

“…The study by McNabb and coworkers applied a multiband fMRI acquisition with an additional fieldmap sequence (McNabb et al, 2018a ). There were other studies which acquired longer rs-fMRI sequences (totaling 11.5 min over two separate acquisitions) with a multiband sequence (Blazer et al, 2022 ; Sarpal et al, 2022a ). Multiecho fMRI sequence was also reported (Pillinger et al, 2019 ).…”

“…During rs-fMRI acquisition, some studies told the participants to keep their eyes open and to look at a fixation cross (White et al, 2016 ; McNabb et al, 2018a , b ; Pillinger et al, 2019 ; Blazer et al, 2022 ; Sarpal et al, 2022a ), while in other studies, they were asked to close their eyes (Alonso-Solís et al, 2015 ; Huang et al, 2018 ; Jiang et al, 2019a , b ; Wang et al, 2020 ; Hu H. et al, 2022 ; Hu Q. et al, 2022 ; Kim et al, 2022 ). Some studies did not report whether the acquisitions were done with open or closed eyes (Ganella et al, 2017 , 2018 ; Gao et al, 2018 ; Yang et al, 2020 ).…”

“…Another study noted that corticostriatal connectivities (i.e., between the right dorsal caudate and the right anterior insula as well as the right inferior frontal gyrus) before the initiation of treatment with CLZ could predict CLZ efficacy, i.e., a reduction in positive symptoms post-treatment (Blazer et al, 2022 ). Furthermore, another study noted that functional connectivity between the basal forebrain and the dorsolateral PFC before the initiation of treatment with CLZ correlated negatively with scores on the Brief Psychiatric Rating Scale (BPRS; Hedlund and Vieweg, 1980 ; Sarpal et al, 2022a ).…”

“…Based on studies in CLZ-treated patients, it seems that the fronto-temporal hypoconnectivity may be specific for non-responders. Five studies (three separate cohorts) investigated individuals with TRS treated with CLZ and reported consistently lower functional connectivity compared to controls (Ganella et al, 2017 , 2018 ; McNabb et al, 2018b ; Blazer et al, 2022 ; Sarpal et al, 2022a ). TRS had lower connectivity predominantly in frontal, temporal, and occipital regions compared to HC (Ganella et al, 2017 ), and in frontal and temporal regions compared to UFM (Ganella et al, 2018 ).…”