Zang YF papers

Disrupted intrinsic functional brain topology in patients with major depressive disorder

Fri, 08/13/2021 - 18:00

Mol Psychiatry. 2021 Aug 12. doi: 10.1038/s41380-021-01247-2. Online ahead of print.


Aberrant topological organization of whole-brain networks has been inconsistently reported in studies of patients with major depressive disorder (MDD), reflecting limited sample sizes. To address this issue, we utilized a big data sample of MDD patients from the REST-meta-MDD Project, including 821 MDD patients and 765 normal controls (NCs) from 16 sites. Using the Dosenbach 160 node atlas, we examined whole-brain functional networks and extracted topological features (e.g., global and local efficiency, nodal efficiency, and degree) using graph theory-based methods. Linear mixed-effect models were used for group comparisons to control for site variability; robustness of results was confirmed (e.g., multiple topological parameters, different node definitions, and several head motion control strategies were applied). We found decreased global and local efficiency in patients with MDD compared to NCs. At the nodal level, patients with MDD were characterized by decreased nodal degrees in the somatomotor network (SMN), dorsal attention network (DAN) and visual network (VN) and decreased nodal efficiency in the default mode network (DMN), SMN, DAN, and VN. These topological differences were mostly driven by recurrent MDD patients, rather than first-episode drug naive (FEDN) patients with MDD. In this highly powered multisite study, we observed disrupted topological architecture of functional brain networks in MDD, suggesting both locally and globally decreased efficiency in brain networks.

PMID:34385597 | DOI:10.1038/s41380-021-01247-2

High-frequency rTMS over the dorsolateral prefrontal cortex on chronic and provoked pain: A systematic review and meta-analysis

Mon, 07/19/2021 - 18:00

Brain Stimul. 2021 Jul 16:S1935-861X(21)00142-X. doi: 10.1016/j.brs.2021.07.004. Online ahead of print.


BACKGROUND: High-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) has demonstrated mixed effects on chronic and provoked pain.

OBJECTIVES/METHODS: In this study, a meta-analysis was conducted to characterise the potential analgesic effects of high-frequency rTMS over the DLPFC on both chronic and provoked pain.

RESULTS: A total of 626 studies were identified in a systematic search. Twenty-six eligible studies were included for the quantitative review, among which 17 modulated chronic pain and the remaining investigated the influence on provoked pain. The left side DLPFC was uniformly targeted in the chronic pain studies. While our data identified no overall effect of TMS across chronic pain conditions, there was significant short-term analgesia in neuropathic pain conditions only (SMD = -0.87). In terms of long-lasting analgesia, there was an overall pain reduction in the mid-term (SMD = -0.53, 24.6 days average) and long-term (SMD = -0.63, 3 months average) post DLPFC stimulation, although these effects were not observed within specific chronic pain conditions. Surprisingly, the number of sessions was demonstrated to have no impact on rTMS analgesia. In the analysis of provoked pain, our data also indicated a significant analgesic effect following HF-rTMS over the DLPFC (SMD = -0.73). Importantly, we identified a publication bias in the studies of provoked pain but not for chronic pain conditions.

CONCLUSIONS: Overall, our findings support that HF-DLPFC stimulation is able to induce an analgesic effect in chronic pain and in response to provoked pain. These results highlight the potential of DLPFC-rTMS in the management of certain chronic pain conditions and future directions are discussed to enhance the potential long-term analgesic effects.

PMID:34280583 | DOI:10.1016/j.brs.2021.07.004

Interhemispheric co-alteration of brain homotopic regions

Fri, 06/25/2021 - 18:00

Brain Struct Funct. 2021 Jun 25. doi: 10.1007/s00429-021-02318-4. Online ahead of print.


Asymmetries in gray matter alterations raise important issues regarding the pathological co-alteration between hemispheres. Since homotopic areas are the most functionally connected sites between hemispheres and gray matter co-alterations depend on connectivity patterns, it is likely that this relationship might be mirrored in homologous interhemispheric co-altered areas. To explore this issue, we analyzed data of patients with Alzheimer's disease, schizophrenia, bipolar disorder and depressive disorder from the BrainMap voxel-based morphometry database. We calculated a map showing the pathological homotopic anatomical co-alteration between homologous brain areas. This map was compared with the meta-analytic homotopic connectivity map obtained from the BrainMap functional database, so as to have a meta-analytic connectivity modeling map between homologous areas. We applied an empirical Bayesian technique so as to determine a directional pathological co-alteration on the basis of the possible tendencies in the conditional probability of being co-altered of homologous brain areas. Our analysis provides evidence that: the hemispheric homologous areas appear to be anatomically co-altered; this pathological co-alteration is similar to the pattern of connectivity exhibited by the couples of homologues; the probability to find alterations in the areas of the left hemisphere seems to be greater when their right homologues are also altered than vice versa, an intriguing asymmetry that deserves to be further investigated and explained.

PMID:34170391 | DOI:10.1007/s00429-021-02318-4