MT, as a form of auditory stimulation, has been extensively studied for its application in patients with dementia. Although patients with dementia exhibit severe deficits in episodic and certain semantic memory, their musical memory remains relatively intact, allowing them to learn new songs, encode new linguistic information, and elicit emotional responses to music^[20]. Therefore, MT can exert a certain influence on patients with dementia by stimulating their auditory system. Bleibel et al.^[21] found that MT can effectively improve cognitive function in patients with dementia and have long-term effects, particularly when patients actively engage in music-making through active music intervention. Meanwhile, Lin et al.^[22], using the Mini-Mental State Examination to assess the impact of MT on Asian patients with dementia, reported that MT may slow down the progression of disease severity. Additionally, Tsoi et al.^[23] found that receptive music therapy can reduce agitation, behavioral problems, and anxiety in patients with dementia and may be more effective than interactive music therapy. Therefore, MT can serve as a valuable strategy for treating patients with dementia and warrants further research into its practical clinical application value.

Visual stimulation has a positive impact on the cognition and mental behavior of patients with Alzheimer's disease. The main forms of visual stimulation applied to these patients are light therapy or horticultural therapy (HT). Sleep disorders may lead to cognitive decline by affecting the clearance of Aβ metabolism in the brain, altering central nervous system plasticity, activating glial cells, and triggering neuroinflammation, thereby increasing the risk of dementia^[24]. Relevant studies have shown that the prevalence of sleep disorders among Alzheimer's patients can be as high as 40%, with symptoms including disrupted sleep architecture, altered sleep-wake rhythms, and sleep-disordered breathing^[25-27]. Different durations and intensities of light exposure in light therapy have varying effects on Alzheimer's patients. Studies indicate that daily light exposure for 2 hours over a period of more than 2 weeks can effectively improve sleep architecture disturbances in Alzheimer's patients and is relatively safe. Light intensities ranging from 3,000 to 8,000 lux can adjust patients' sleep rhythms, enhance daytime circadian stimulation, and improve nighttime sleep quality. Short-wavelength blue light and white light can effectively correct circadian rhythm disturbances, helping to regulate patients' sleep-wake cycles, though further research is still needed^[28]. In addition to sleep disorders, Alzheimer's patients may also experience other mental health issues. Zou et al.^[29]conducted a 4-week randomized controlled trial and found that one course of 4-week phototherapy significantly reduced delirium in patients with psychiatric and psychological conditions by regulating their biological rhythms, effectively alleviating the caregiving burden on caregivers. Apathy is one of the most common behavioral and psychological symptoms in Alzheimer's patients^[30], and effective interventions should be implemented to improve apathy in these patients. Horticultural therapy (HT) is a therapeutic approach that utilizes plants, gardening activities, and natural environments to enhance participants' cognitive, physical, psychological, and social well-being^[31]. Yang et al.^[32]conducted a randomized controlled study and found that HT can effectively reduce apathy and promote cognitive function in Alzheimer's patients, though there are fewer reports on its effects on improving patients' quality of life. Future research should focus on the role of visual stimulation in enhancing the quality of life for Alzheimer's patients.

Changes in olfactory function are considered an early biomarker of neurodegenerative changes^[12], making the study of olfactory stimulation in patients with dementia equally important. Aromatherapy (AT) is a traditional complementary and alternative therapy that focuses on preventing and treating diseases by inhaling aromatic plant extracts^[33]. As an economical, safe, and effective non-pharmacological intervention, the application of AT in dementia patients has become a research hotspot among foreign scholars, while in China, research on AT in elderly dementia patients is still at an initial stage. Among sensory systems, the olfactory system has the most direct and close physiological and pathological connections with the brain. Olfaction plays a regulatory role in various physiological and psychological states of humans, including emotions, learning, and memory. AT can be used to intervene or assist in the intervention of neurological disorders^[34]. Abroad, especially in medical institutions, it is commonly used to improve cognitive function, psychiatric symptoms, and sleep in elderly dementia patients. Early studies have found that AT has certain potential in improving cognitive function in elderly dementia patients^[35]. However, a systematic review on the effects of AT interventions in dementia patients published by Ball et al.^[36]indicated that the efficacy of AT remains uncertain, but at the same time highlighted its non-invasive safety, suggesting that more high-quality clinical trials are needed in the future to confirm its effectiveness.

Forms of tactile stimulation applied to patients with dementia primarily include massage/touch therapy and DT. Massage refers to the stimulation of superficial and deep tissues of muscles and connective tissues using various techniques^[37], and is a type of tactile stimulation. Behavioral and psychological symptoms of dementia (BPSD) are common psychiatric symptoms in patients with dementia. Abraha et al.^[38], through a search of multiple databases, found that massage/touch can effectively improve BPSD symptoms in patients with dementia, thus healthcare professionals and family caregivers should be encouraged to provide massage to these patients. Meanwhile, Rodríguez-Mansilla et al.^[39], through a randomized controlled trial conducted on dementia patients in a certain region of Spain, found that massage therapy could effectively alleviate pain, anxiety, depression, and other symptoms. In addition, Wan Chengxian et al.^[40], after performing acupoint massage on 80 elderly dementia patients for 6 months, measured their cognitive abilities using the Mini-Mental State Examination scale after the intervention, and found that appropriate head acupoint massage could effectively improve cognition in elderly dementia patients. DT is a person-centered and humanistic non-pharmacological treatment method. The forms of interaction between dementia patients and dolls are diverse, including talking to dolls, hugging them, feeding them, and dressing them^[41]. Yilmaz et al.^[42], after conducting an 8-week DT intervention on 29 elderly dementia patients in a Turkish nursing home, found that DT could effectively improve individual cognitive function and reduce agitation and other behavioral disturbances in elderly dementia patients. Furthermore, Santagata et al.^[43], through a randomized controlled trial involving 52 dementia patients in Italian nursing homes, showed that DT could reduce BPSD symptoms and mental confusion, thereby alleviating the burden on caregivers and improving their quality of life. Therefore, applying tactile stimulation to elderly dementia patients through massage therapy or DT significantly improves their cognition and BPSD symptoms.

Taste dysfunction is considered a sensitive indicator for detecting preclinical AD in patients with subjective cognitive decline^[44]. Therefore, it is essential to apply certain methods to provide taste stimulation for AD patients. Currently, research on the application of taste stimulation in elderly dementia patients is limited. Wang et al.^[45] found through in vitro and in vivo studies that capsaicin intake can reduce the production of brain β-amyloid and alleviate AD-like pathological features and cognitive deficits in amyloid precursor protein/pre-senilin 1 transgenic mice. Additionally, Wang et al.^[46] focused on dietary factors and proposed an intervention phase, finding that modified Mediterranean-ketogenic diets, nuts, vitamin B, and Bifidobacterium A1, among others, effectively improve cognitive function in dementia patients by stimulating taste buds through various flavors. Therefore, relevant taste stimulation interventions are crucial for elderly dementia patients, and future research should focus more on this area.

Multisensory environmental therapy can enhance the initiative of elderly patients with dementia to a certain extent through multisensory stimulation, potentially improving interaction and communication between patients and caregivers, thereby enhancing their quality of life and reducing the burden on caregivers^[48]. Snoezelen is a multisensory environmental therapy originating from the Netherlands, which creates a comfortable and relaxing atmosphere to help individuals with special needs (such as autism and dementia) improve their mood, behavior, and cognitive abilities^[49]. Klages et al.^[50]conducted multisensory stimulation sessions twice a week for 30 minutes in a Snoezelen room with nine elderly dementia patients and found that the Snoezelen room has the potential to improve balance in dementia patients, thus warranting further large-scale, long-term follow-up studies to explore its long-term effectiveness. Pinto et al.^[10]research indicated that the Snoezelen room has positive effects on the behavioral and psychological aspects of dementia patients, but future follow-up evaluations are still needed to assess its effectiveness. In addition to the Snoezelen room, healing gardens and sensory gardens also have certain effects on the behavior and mental-psychological state of elderly dementia patients. Gueib et al.^[51]found that healing gardens can effectively improve self-awareness in elderly dementia patients. Sensory gardens are surrounded by fences or walls, ensuring patient safety while utilizing fresh air, floral scents, birdsong, warm sunlight, and other stimuli to activate various sensory systems, thereby alleviating negative emotions and sleep disorders in elderly dementia patients^[52]. However, currently there is limited research in China on healing gardens and sensory gardens, and more comprehensive studies are still needed in the future to explore how they can bring greater health benefits to elderly dementia patients.

In recent years, virtual reality (VR) technology has been applied as a novel sensory stimulation method for patients with dementia. VR technology creates a three-dimensional space through digital means, allowing people to interact within it and receive various sensory inputs^[53]. VR can be either fully immersive or partially immersive, with the degree of immersion enabling individuals to experience a sense of real presence in the environment^[53]. Oliveira et al.^[54]conducted a study involving 17 dementia patients from Portuguese nursing homes and found that non-immersive VR technology, by providing visual and auditory stimuli to create an immersive experience, effectively stimulates neurocognition in dementia patients and helps maintain their cognitive function. Additionally, the duration of intervention may lead to different therapeutic effects. Basic VR training promotes real-time interaction among visual, auditory, and tactile senses through multiple sensory channels, simultaneously stimulating motor and cognitive processes^[55-57]. Studies have shown that VR-based rehabilitation training can effectively improve cognition, motor skills, and daily functioning in dementia patients. Immersive VR-based training has a greater impact on cognitive and motor functions compared to non-immersive VR-based training; however, non-immersive VR-based training is more convenient for patients whose activities are restricted due to their condition^[58]. Furthermore, interventions lasting 5 to 8 weeks, conducted at a frequency of ≥3 sessions per week for more than 30 minutes each, achieved the best results^[58]. In summary, multisensory stimulation therapy is a promising treatment approach that plays an important role in alleviating symptoms and managing dementia. However, its underlying mechanisms and specific forms of stimulation still require further exploration and refinement.