Dementia and frailty increase health adversities in older adults, which are topics of growing research interest. Frailty is considered to correspond to a biological syndrome associated with age. Frail patients may ultimately develop multiple dysfunctions across several systems, including stroke, transient ischemic attack, vascular dementia, Parkinson's disease, Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, cortico-basal degeneration, multiple system atrophy, amyotrophic lateral sclerosis, and Creutzfeldt-Jakob disease. Patients with dementia and frailty often develop malnutrition and weight loss. Rigorous nutritional, pharmacological, and non-pharmacological interventions generally are required for these patients, which is a challenging issue for healthcare providers. A healthy diet and lifestyle instigated at an early age can reduce the risk of frailty and dementia. For optimal treatment, accurate diagnosis involving clinical evaluation, cognitive screening, essential laboratory evaluation, structural imaging, functional neuroimaging, and neuropsychological testing is necessary. Diagnosis procedures best apply the clinical diagnosis, identifying the cause(s) and the condition(s) appropriate for treatment. The patient's history, caregiver's interview, physical examination, cognitive evaluation, laboratory tests, and structural imaging should best be involved in the diagnostic process. Varying types of physical exercise can aid the treatment of these disorders. Nutrition maintenance is a particularly significant factor, such as exceptionally high-calorie dietary supplements and a Mediterranean diet to support weight gain. The core purpose of this article is to investigate trends in the management of dementia and frailty, focusing on improving diagnosis and treatment. Substantial evidence builds the consensus that a combination of balanced nutrition and good physical activity is an integral part of treatment. Notably, more evidence-based medicine knowledge is required.