High-frequency rTMS of the left dorsolateral prefrontal cortex for post-stroke depression: A systematic review and meta-analysis.

OBJECTIVE: This meta-analysis investigated the therapeutic efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) for treatment of post-stroke depression (PSD). METHODS: Ten articles with 266 patients in rTMS group and 258 patients in control group were included. The primary outcome was performed to examine the efficacy of rTMS for PSD. Secondary outcomes of response rates and remission rates and subgroup analyses were further explored. RESULTS: Our meta-analysis revealed a significant pooled effect size (the standard mean difference (SMD) was -1.45 points (95% CI, -2.04 to -0.86; p < 0.00001)). The odds ratio (OR) of the response rate and remission rate were 8.41 (95% CI, 2.52-28.12, p = 0.0005) and 6.04 (95% CI, 1.5-24.39, p = 0.01). Moreover, rTMS treatment for PSD patients in subacute phase and targeting the left DLPFC at 5-cm anterior to the left motor hotspot or the midpoint of the middle frontal gyrus showed significant antidepressant effect. In addition, the Hamilton Depression Rating Scale (HAMD) was sensitive to detect depressive changes in patients. CONCLUSIONS: Our meta-analysis elucidated that the application of high-frequency rTMS over the left DLPFC was an effective treatment alternative for PSD. SIGNIFICANCE: Our meta-analysis may help to develop more reasonable treatment strategies in clinical practice for PSD patients.

Depression circuit adaptation in post-stroke depression.

BACKGROUND: Lesion locations of post-stroke depression (PSD) mapped to a depression circuit which centered by the left dorsolateral prefrontal cortex (DLPFC). However, it remains unknown whether the compensatory adaptations that may occur in this depression circuit due to the lesions in PSD. METHODS: Rs-fMRI data were collected from 82 non-depressed stroke patients (Stroke), 39 PSD patients and 74 healthy controls (HC). We tested the existence of depression circuit, examined PSD-related alterations of DLPFC-seeded connectivity and their associations with depression severity, and analyzed the connectivity between each repetitive transcranial magnetic stimulation (rTMS) target and DLPFC to find the best treatment target for PSD. RESULTS: We found that: 1) the left DLPFC showed significantly stronger connectivity to lesions of PSD than Stroke group; 2) in comparison to both Stroke and HC groups, PSD exhibited increased connectivity with DLPFC in bilateral lingual gyrus, contralesional superior frontal gyrus, precuneus, and middle frontal gyrus (MFG); 3) the connectivity between DLPFC and the contralesional lingual gyrus positively correlated with depression severity; 4) the rTMS target in center of MFG showed largest between-group difference in connectivity with DLPFC, and also reported the highest predicted clinical efficacy. LIMITATIONS: Longitudinal studies are required to explore the alterations of depression circuit in PSD as the disease progress. CONCLUSION: PSD underwent specific alterations in depression circuit, which may help to establish objective imaging markers for early diagnosis and interventions of the disease.

Repetitive transcranial magnetic stimulation modulates cortical-subcortical connectivity in sensorimotor network.

Repetitive transcranial magnetic stimulation (rTMS) holds the ability to modulate the connectivity within the stimulated network. However, whether and how the rTMS targeted over the primary motor cortex (M1) could affect the connectivity within the sensorimotor network (SMN) is not fully elucidated. Hence, in this study, we investigated the after-effects of rTMS over left M1 at different frequencies on connectivity within SMN. Forty-five healthy participants were recruited and randomly divided into three groups according to rTMS frequencies (high-frequency [HF], 3 Hz; low-frequency [LF], 1 Hz; and SHAM). Participants received 1-Hz, 3-Hz or sham stimulation and underwent two functional magnetic resonance imaging (fMRI) scanning sessions before and after rTMS intervention. Using resting-state functional connectivity (FC) approach, we found that high- and low-frequency rTMS had opposing effects on FC within the SMN, especially for connectivity with subcortical regions (i.e., putamen, thalamus and cerebellum). Specifically, the reductions in connectivity between cortical and subcortical regions within cortico-basal ganglia thalamo-cortical circuits and the cognitive loop of cerebellum, and increased connectivity between cortical and subdivisions within the sensorimotor loop of cerebellum were observed after high-frequency rTMS intervention, whereas the thalamus and cognitive cerebellum subdivisions exhibited increased connectivity, and sensorimotor cerebellum subdivisions showed decreased connectivity with stimulated target after low-frequency stimulation. Collectively, these findings demonstrated the alterations of connectivity within SMN after rTMS intervention at different frequencies and may help to understand the mechanisms of rTMS treatment for movement disorders associated with deficits in subcortical regions such as Parkinson's disease, Huntington's disease and Tourette's syndrome.