ABSTRACT Frailty and Alzheimer's Disease (AD), and AD-related dementias ([ADRD]hereafter dementia) are progressive conditions that disproportionally affect the same age group and share many risk factors and clinical features. In fact, frailty and dementia are interrelated such that dementia might precipitate manifestation of frailty, and frailty might influence the clinical manifestation of dementia in person with AD brain pathology. Given that no treatments prevent and slow the progression of dementia, frailty might be a practical target for interventions aimed at reducing the severity of the cognitive decline in persons with dementia. Lifestyle interventions such as healthy eating reduce risks of frailty and brain degeneration. While several frailty and brain-friendly dietary interventions exist, the Mediterranean diet (MedD), is especially pertinent because of cardioprotective, anti- inflammatory and pro-metabolic properties, all of which are linked to the pathophysiology of frailty and AD. Evidence also emerge on cognitive benefits of MedD in persons with AD. Previous behavioral dietary interventions, however, were limited for implementation at the population level because of the high cost of intervention delivery. Mobile-based health (mHealth) interventions, being inexpensive and technologically advanced, present an attractive alternative for delivering scalable dietary interventions in this population. We propose to extend our previous work, in which we developed a mHealth intervention to improve adherence to MedD in older adults with frailty but without cognitive deficits, to a growing multimorbid population of older adults with frailty as well as cognitive impairment. Specifically, we propose to use principles of human-centered design to tailor our previously developed app to also accommodate older adults with mild-to-moderate dementia and their care partners. We envision the use of the app as a shared tool, where the user with dementia may work with their care partners for some aspects of its use. The proposed study activities will include interviews with experts in dementia, nutrition, and behavioral health and focus groups with individuals with mild-to-moderate dementia and their care partners. We will also involve human-computer interaction experts with experience in accessible design. We will employ iterative design principles to refine and enhance the mobile app during usability studies. This is a perfect opportunity to extend our current work and engage people with an early cognitive loss and their care partners to ensure that the app is accessible by this population. In the original application, we suggested to exclude people with cognitive deficits, but by involving people with different levels of cognitive abilities in the app development process, we will ensure that the ultimate design will support access by the broadest demographic. As such, the app may be used in the future in secondary dementia risk reduction studies.