Environmental factors in the daily lives of people with dementia are not disease-modifying agents that directly influence neurodegenerative pathology. However, inadequate lighting, reduced nighttime visibility, complex pathways, excessive sensory stimulation, and unpredictable environmental changes frequently trigger delirium, nighttime agitation, falls, sleep fragmentation, and behavioral and psychological symptoms of dementia (BPSD). These in turn significantly accelerate disease progression, leading to increased rates of hospitalization, institutionalization, and caregiving breakdown.Many existing environmental improvement strategies are based on architectural ideals or comprehensive design theories, often lacking sufficient consideration for feasibility or sustainability in home or care settings. The aim of this paper is to redefine environmental interventions for people with dementia not as a form of treatment, but as a method to control progression-accelerating factors. By decomposing existing guidelines and environmental design research into "core active ingredients" and "excessive cognitive or operational burdens," we propose a minimal intervention model that can be sustainably implemented in real-world care settings.From an integrated review of the literature, we identify three core environmental intervention components for dementia care: (1) lighting that provides clear temporal cues for day and night; (2) simplified and visible nighttime pathways; and (3) optimization of sensory input, particularly through reduction of noise and unpredictable stimuli. These components do not halt disease progression, but they serve as a highly practical foundation for non-pharmacological interventions by mitigating acute deterioration events such as delirium, falls, BPSD, and hospitalization. This paper presents a model that organizes these relationships into a cascade of progression accelerators and proposes a feasible environmental intervention framework.