Vitamin D and Cognition Trial

This study is testing whether taking vitamin D supplements for 18 months can slow down memory and thinking problems in older adults who have mild cognitive impairment (MCI) and low vitamin D levels. MCI is when a person notices some memory or thinking changes, but they are still able to carry out daily activities. Low vitamin D levels are common in older adults and have been linked to brain health. This trial aims to find out if correcting low vitamin D can protect the brain from getting worse. Researchers will also look at quality of life, walking, balance, and muscle strength. You may be eligible if: - You are over 65 years of age - You have been diagnosed with mild cognitive impairment (MCI) - Your vitamin D blood level is between 12.5 and 50 nmol/L (low range) You may NOT be eligible if: - You have been diagnosed with dementia - You have osteoporosis that requires treatment - You have no family member or friend who can provide information about you - You have had a stroke, heart attack, or fall in the last 3 months - You have had a fall with a fracture after the age of 65 - You have kidney or bladder stones - You have current severe depression or a history of schizophrenia - You have a significant hearing or vision problem that would interfere with tests Talk to your doctor about whether this trial might be right for you.