Alzheimer's disease (AD) is a prevalent neurodegenerative disorder, characterized by the accumulation of beta-amyloid plaques, the phosphorylation of Tau proteins, and neuronal loss. As the global population ages, the incidence of AD is rising, and there is currently no effective cure.Herbal monomers have garnered interest due to their multifaceted pharmacological effects and low toxicity. This paper aims to provide a comprehensive overview of the mechanisms of Nrf2, NF-κB, PI3K/Akt, MAPK and other signalling pathways in the pathogenesis of AD. It also explores the modulation of these pathways by various TCM monomers, such as leptomeningine and tanshinone IIA, and details the research progress to date. For instance, Leptosine has been shown to activate Nrf2, thereby reducing oxidative stress, while Tanshinone IIA has been observed to inhibit the NF-κB pathway, leading to a reduction in inflammation. Notwithstanding the encouraging indications for the treatment of AD with TCM monomers, there are several challenges that must be addressed. Firstly, the precise mechanism of action remains to be fully elucidated. Secondly, there are significant challenges related to pharmacokinetics and bioavailability. Thirdly, the sample size of clinical studies is limited and of variable quality. Fourthly, the quality control process is complex. Finally, interactions with other drugs must be taken into account.