From Sensory Deprivation to Psychosis: Environmental Mechanisms of Delirium in Dementia—An Eight-Year Retrospective Longitudinal Case Report and Narrative Review

Vollständiger Abstract

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Background/Objectives: Delirium in patients with dementia is a multifactorial condition traditionally attributed to acute medical triggers. However, emerging evidence suggests that non-biological factors, including sensory deprivation and environmental instability, may contribute to delirium vulnerability, particularly in vulnerable populations. To explore the temporal associations between non-biological and environmental factors, particularly sensory deprivation and recurrent delirium in a patient with advanced Alzheimer’s disease and progressive vision loss, a narrative review was conducted. Methods: A narrative review of the literature on delirium risk factors, differential diagnosis, and non-pharmacological interventions was conducted. A retrospective longitudinal case report of a patient with advanced Alzheimer’s disease and progressive visual impairment, based on an eight-year observation, was used to contextualize the literature findings. Results: The literature indicates that delirium arises from the interaction between predisposing factors, such as cognitive impairment and reduced cognitive reserve, and precipitating factors, including both biological and environmental stressors. Sensory deprivation, particularly visual impairment, may significantly disrupt orientation and increase reliance on internally generated perceptual content, predisposing to hallucinations and delusions. Environmental instability, such as changes in caregivers, disrupted routines, and overstimulation, may further exacerbate this vulnerability. Evidence suggests that these factors may contribute to delirium even in the absence of identifiable classical medical triggers. In the presented case, individualized non-pharmacological interventions based on structured routines, environmental predictability, and sensory-adapted engagement were associated with periods of improved behavioral stability. Conclusions: The present case supports the hypothesis that delirium in dementia may involve impaired environmental integration, particularly in the context of sensory deprivation, in addition to established biological mechanisms. Person-centered non-pharmacological strategies aimed at maintaining familiarity, environmental predictability, and appropriate sensory support may represent valuable components of delirium prevention and management. These hypothesis-generating observations require confirmation in prospective studies involving larger patient populations.