Early intervention 20 years before Alzheimer's disease symptom onset results in greater prevention efficacy compared to treatment initiated after clinical diagnosis.

Study: An online multidomain lifestyle intervention to prevent cognitive decline in at-risk older adults: a randomized controlled trial

This study showed that helping older adults eat better, exercise more, stay mentally active, and manage mood can improve their memory and thinking skills over three years — suggesting that making healthy changes early may help prevent or delay dementia.

Study: The associations between fresh vegetable and fruit consumption and plasma and PET biomarkers in preclinical Alzheimer's disease: A cross-sectional and longitudinal study of Chinese population

Eating more fruits and vegetables early on, before memory problems start, was linked to less buildup of harmful brain proteins and slower memory loss. This suggests stopping Alzheimer’s before symptoms appear might work better than trying to fix it after it’s already causing damage.

Study: Intervention on Modifiable Lifestyle and Physiological Factors via Variational Autoencoder Reveals Changes in Functional Connectivity-Mediated Risk for Alzheimer’s Disease

This study shows that things like smoking, being overweight, or not sleeping well when you're young can change your brain in ways that make Alzheimer’s more likely later. Fixing these habits early may stop the disease before it starts—much better than trying to fix it after memory problems appear.