Uncovering the intricacies of IGF-1 in Alzheimer's disease: new insights from regulation to therapeutic targeting.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-β plaques and tau tangles, leading to cognitive decline and dementia. Insulin-like Growth Factor-1 (IGF-1) is similar in structure to insulin and is crucial for cell growth, differentiation, and regulating oxidative stress, synaptic plasticity, and mitochondrial function. IGF-1 exerts its physiological effects by binding to the IGF-1 receptor (IGF-1R) and activating PI3K/Akt pathway. In addition to the physiological activities in the brain, numerous studies point to a potential protective role of the IGF-1 pathway in the pathogenesis of neurodegenerative diseases, such as AD. Interestingly, patients with AD often exhibit altered insulin and IGF-1 levels, along with an inadequate insulin response. Dysregulation of IGF-1 signaling contributes to hyperphosphorylation of tau, NFT accumulation, increased β- and γ-secretase activity, elevated Aβ production, and impaired Aβ clearance, highlighting the need to explore the role of this signaling for potential therapeutic targets of AD. This review explores the role of IGF signaling in AD pathology, highlighting IGF-1 as a promising therapeutic target due to its significant involvement in disease mechanisms. Modulating IGF-1 activity could help mitigate neurodegeneration and preserve cognitive function in AD. A comprehensive understanding of the mechanisms underlying IGF-1 dysregulation is crucial for developing targeted therapeutic strategies to address the complex and multifaceted nature of AD.