Background Individuals with dementia are particularly vulnerable during emergency situations due to challenges with cognition, mobility, and daily functioning. However, little is known about how disruptive events may specifically impact the health of those with dementia. Objective To evaluate changes in health outcomes for individuals with and without dementia surrounding the Israel-Gaza war in October 2023. Specifically, we analyzed and compared changes in mental health status, medication adherence, healthcare service utilization, and associated costs between individuals with dementia (Study Group) and those without dementia (Control Group) during the period surrounding the Israel-Gaza war in October 2023. Method A prospective cohort study compared outcomes between individuals with dementia (Study Group, n = 24,178) and without (Control Group, n = 250,652) before and after the crisis onset. The conflict precipitously threw national systems into disarray, recruited healthcare personnel to the war effort, and disrupted supply chains. Results Compared to baseline, analysis revealed alterations in patterns of dementia diagnoses, healthcare service utilization, medication adherence, and associated costs during the crisis period for both groups. However, the Study Group experienced comparatively larger declines. Conclusions Findings provide insights into how humanitarian emergencies, through disruption of health systems and care networks, differentially impact continuity of dementia care. This underscores the need for tailored crisis response strategies to address the heightened vulnerabilities of patients with dementia.