Mild cognitive impairment (MCI) and early Alzheimer's disease (AD) present significant challenges in aging populations, as cognitive decline impacts daily life and overall well-being. There has been a growing interest in non-pharmacological interventions that can mitigate the progression of these conditions. This review explores the impact of various interventions, including physical activity, nutrition, cognitive training, and multidomain approaches, on cognitive function in individuals with MCI or early AD. Studies have demonstrated the potential of exercise, particularly aerobic and strength training, to improve cognitive health by preserving brain structure and function. Nutritional interventions, particularly those focusing on Mediterranean-style diets, offer promising cognitive benefits due to their anti-inflammatory properties. Cognitive training programs have shown improvements in specific cognitive domains, but results regarding their long-term effectiveness are still inconclusive. Multidomain interventions that combine exercise, nutrition, and cognitive training show potential for optimizing cognitive function and reducing the risk of further cognitive decline. However, while these studies offer promising results, more large-scale, long-term trials are needed to confirm the sustained impact of these interventions and identify the most effective strategies for preventing dementia.