Older adults with significant fluctuations in cholesterol levels are at increased risk for dementia and cognitive decline, even without medication changes. Researchers studied nearly 10,000 older adults, tracking their cholesterol levels and cognitive function over six years. High variability in total and LDL ("bad") cholesterol was associated with a 60% increase in dementia and 23% increase in cognitive decline.

Higher levels of HDL, the so-called "good cholesterol," may not protect against Alzheimer's in postmenopausal women, with the risk potentially tied to the quality, not quantity, of HDL particles. A new study shows that larger HDL particles, which increase during menopause, lose efficiency in supporting cognitive health.