Objectives The screening of dementia among geriatrics is necessary to identify probable cases, confirm diagnosis, institute treatment, and plan for future family caregiving strategies. This study aimed to screen the incidence of dementia among geriatric patients using the informant-based Alzheimer's disease eight-item tool for dementia (AD8) in a KSA region. Methods A cross-sectional study was conducted among geriatric patients in the KSA region at selected hospitals from December 2019 to March 2020. The caregivers of 100 geriatric patients were interviewed using the AD8. Results Among the 100 patients, 43% were 65–75 years old, 52% were men, and 48% were women, mean age was (78) for both genders. Diabetes mellitus was the most reported chronic illness, found in 68% of the patients, followed by a history of cerebrovascular disease (52%). Loss of more than four but less than half of the teeth was reported in 41% of the patients, while 10% were reported to be undergoing polypharmacy. Dementia was diagnosed in 74% of patients and had a statistically significant association with a history of stroke ( p < 0.001), number of teeth lost ( p = 0.02), and number of drugs administered ( p = 0.006). A binary logistic regression model fitted to predict dementia based on the effect of a stroke history, number of missing teeth, and number of drugs administered showed that patients with stroke were 1.43 (95% CI 1.4–4.2) times likely to develop dementia than those with no history of stroke. Conclusion Cases of dementia are frequent among geriatric patients in the Qassim region of KSA. A dementia positive screening is correlated with a history of stroke, number of lost teeth, polypharmacy, and age. Stroke prevention and early treatment can potentially reduce the likelihood of dementia occurrence.