PLoS ONE (Jan 2023)

Outcomes and clinical implications of intranasal insulin on cognition in humans: A systematic review and meta-analysis.

  • Sally Wu,
  • Nicolette Stogios,
  • Margaret Hahn,
  • Janani Navagnanavel,
  • Zahra Emami,
  • Araba Chintoh,
  • Philip Gerretsen,
  • Ariel Graff-Guerrero,
  • Tarek K Rajji,
  • Gary Remington,
  • Sri Mahavir Agarwal

DOI
https://doi.org/10.1371/journal.pone.0286887
Journal volume & issue
Vol. 18, no. 6
p. e0286887

Abstract

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BackgroundAberrant brain insulin signaling has been posited to lie at the crossroads of several metabolic and cognitive disorders. Intranasal insulin (INI) is a non-invasive approach that allows investigation and modulation of insulin signaling in the brain while limiting peripheral side effects.ObjectivesThe objective of this systematic review and meta-analysis is to evaluate the effects of INI on cognition in diverse patient populations and healthy individuals.MethodsMEDLINE, EMBASE, PsycINFO, and Cochrane CENTRAL were systematically searched from 2000 to July 2021. Eligible studies were randomized controlled trials that studied the effects of INI on cognition. Two independent reviewers determined study eligibility and extracted relevant descriptive and outcome data.ResultsTwenty-nine studies (pooled N = 1,726) in healthy individuals as well as those with Alzheimer's disease (AD)/mild cognitive impairment (MCI), mental health disorders, metabolic disorders, among others, were included in the quantitative meta-analysis. Patients with AD/MCI treated with INI were more likely to show an improvement in global cognition (SMD = 0.22, 95% CI: 0.05-0.38 p = ConclusionsThis review demonstrates that INI may be associated with pro-cognitive benefits for global cognition, specifically for individuals with AD/MCI. Further studies are required to better understand the neurobiological mechanisms and differences in etiology to dissect the intrinsic and extrinsic factors contributing to the treatment response of INI.