Due to the complexity of Alzheimer's disease (AD), its treatment is extremely challenging. However, the multifaceted nature of AD, our incomplete understanding of underlying pathways, and potential limitations of existing drugs contribute to the high treatment failure rate [1]. Traditionally approved and marketed treatments mostly revolve around cholinesterase inhibitors, glutamate modulators, or combinations of these drugs [2]. The failure of several promising drugs in large phase III trials underscores the need for novel approaches. Some new therapeutic approaches have been developed recently, which may address the limitations of conventional approaches. First, monoclonal antibodies targeting Aβ plaques, such as Lecanemab and Donanemab, have demonstrated disease-modifying effects by significantly slowing cognitive decline in early-stage AD patients [3]. Moreover, emerging immunomodulatory strategies focus on microglial dysfunction and neuroinflammation. Inhibition of the cGAS-STING pathway in microglia was shown to reduce Aβ deposition and restore intercellular communication in the AD mice model, suggesting its potential as a dual-target mechanism for both Aβ and neuroinflammation [4]. Additionally, non-pharmacological interventions like gamma-frequency neuromodulation, a digital therapy using 40 Hz audiovisual stimulation, slow the progression of AD by activating the glial lymphatic system of the brain to clear Aβ proteins [5], highlighting the role of neurophysiological modulation. These innovations underscore the importance of combining different therapies to achieve synergistic benefits. Consequently, trials to investigate rational combination treatment should continue.

In fact, many studies have demonstrated the clinical efficacy of combination treatment over monotherapy [6]. The additive effect of combination treatment may be important for patient outcomes. Combination treatment can even lower the dose of a single drug, reducing costs and side effects. Numerous studies have shown that exercise can regulate the transformation of Aβ, inflammation, cerebral blood flow, and the synthesis and release of neurotrophins, all of which positively impact cognition [7]. However, there is also evidence suggesting that exercise interventions do not consistently improve cognitive function in subjects [8]. This implies that the duration, frequency, and/or intervention intensity of exercise need to reach a certain threshold to effectively improve cognitive impairment. Exercise combined with other interventions may weaken the demand for these factors. One study showed that acute and long-term supplementation of luteolin combination during sprint exercise can improve performance, muscle O2 extraction, and brain oxygenation [9], which inspired us to wonder if there is a synergistic effect of luteolin and exercise combination treatment in improving AD-related cognitive impairment (ARCI). In recent years, the potential of luteolin in treating ARCI has been gradually discovered. Luteolin is a kind of flavonoid widely distributed in the plant world, which has antioxidant, anti-inflammatory, neuroprotective, and anticancer effects [10]. Studies have revealed that it can inhibit the endoplasmic reticulum stress-dependent neuroinflammation in AD mice [11]. Additionally, other studies have confirmed its neuroprotective effect on AD-related Aβ accumulation, neuronal apoptosis, and mitochondrial damage in AD mice [11]. Our previous study demonstrated that luteolin and exercise combination treatment (Lut + Exe) can effectively improve ARCI. Compared to monotherapy, this combination approach holds promise as a viable strategy for AD treatment [12]. However, the precise mechanisms and targets underlying this synergistic effect remain incompletely elucidated.

In this study, we postulated that combination treatment could alter the metabolic profile to enhance cognitive impairment by improving the overall state of Aβ1-42 oligomer-induced AD models. To better understand the biological relationship between endogenous metabolites and combination treatment, we employed liquid chromatography-mass spectrometry (UPLC/Q-TOF-MS) to perform plasma metabolomics analysis. Furthermore, we explored the target of combination treatment through differential metabolite analysis and pathway analysis. The objective of our study was to clarify the mechanism by which Lut + Exe ameliorates ARCI, as well as to offer a theoretical and experimental foundation for future applications.