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Effect of Vagus Nerve Stimulation on Attention and Working Memory in Neuropsychiatric Disorders: A Systematic Review

  • Daruj Aniwattanapong
    Correspondence
    Address correspondence to: Daruj Aniwattanapong, MD, Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Rd, Pathum Wan, Bangkok 10330, Thailand.
    Affiliations
    Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand

    Chulalongkorn Cognitive, Clinical & Computational Neuroscience Lab, Chula Neuroscience Center, King Chulalongkorn Memorial Hospital, Bangkok, Thailand

    Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
    Search for articles by this author
  • Justine J. List
    Affiliations
    Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA

    Mental Health Care Line, Michael E. DeBakey Veterans Affairs Medical Center, Baylor College of Medicine, Houston, TX, USA
    Search for articles by this author
  • Nithya Ramakrishnan
    Affiliations
    Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA

    Mental Health Care Line, Michael E. DeBakey Veterans Affairs Medical Center, Baylor College of Medicine, Houston, TX, USA
    Search for articles by this author
  • Gursimrat S. Bhatti
    Affiliations
    Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA

    Mental Health Care Line, Michael E. DeBakey Veterans Affairs Medical Center, Baylor College of Medicine, Houston, TX, USA
    Search for articles by this author
  • Ricardo Jorge
    Affiliations
    Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA

    Mental Health Care Line, Michael E. DeBakey Veterans Affairs Medical Center, Baylor College of Medicine, Houston, TX, USA
    Search for articles by this author
Published:January 26, 2022DOI:https://doi.org/10.1016/j.neurom.2021.11.009

      Abstract

      Background

      It has been suggested that vagus nerve stimulation (VNS) may enhance attention and working memory. The neuromodulator effects of VNS are thought to activate the release of neurotransmitters involving cognition and to promote neuronal plasticity. Therefore, VNS has been studied for its effects on attention and working memory impairment in neuropsychiatric disorders.

      Objectives

      This study aimed to assess the effects of VNS on attention and working memory among patients with neuropsychiatric disorders, examine stimulation parameters, provide mechanistic hypotheses, and propose future studies using VNS.

      Materials and Methods

      We conducted a systematic review using electronic databases MEDLINE (Ovid), Embase (Ovid), Cochrane library, and PsycINFO (Ovid). Narrative analysis was used to describe the therapeutic effects of VNS on attention and working memory, describe stimulation parameters, and propose explanatory mechanisms.

      Results

      We identified 20 studies reporting VNS effects on attention and working memory in patients with epilepsy or mood disorders. For epilepsy, there was one randomized controlled trial from all 18 studies. It demonstrated no statistically significant differences in the cognitive tasks between active and control VNS. From a within-subject experimental design, significant improvement of working memory after VNS was demonstrated. One of three nonrandomized controlled trials found significantly improved attentional performance after VNS. The cohort studies compared VNS and surgery and found attentional improvement in both groups. Nine of 12 pretest-posttest studies showed improvement of attention or working memory after VNS. For mood disorders, although one study showed significant improvement of attention following VNS, the other did not.

      Conclusions

      This review suggests that, although we identified some positive results from eligible studies, there is insufficient good-quality evidence to establish VNS as an effective intervention to enhance attention and working memory in persons with neuropsychiatric disorders. Further studies assessing the efficacy of such intervention are needed.

      Keywords

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