Hypertension may predict dementia in older adults with particular cognitive deficits

A study following 837 people with MCI, of whom 414 (49.5%) had at least one vascular risk factor, has found that those with risk factors such as high blood pressure, diabetes, cerebrovascular disease and high cholesterol were twice as likely to develop Alzheimer's disease. Over five years, 52% of those with risk factors developed Alzheimer's, compared to 36% of those with no risk factors In total, 298 people (35.6%) developed Alzheimer's.

Two mouse experiments have found that the drug carvedilol, prescribed for the treatment of hypertension, significantly improved synaptic transmission in Alzheimer's disease-type brains, and at a behavioral level significantly improved learning and memory.

Part of the Women's Health Initiative study looking at the effect of hormone therapy on thinking and memory in postmenopausal women, involving over 1400 women, has found those who had high blood pressure at the start of the study (eight years earlier) had significantly higher amounts of white matter lesions. Damage to white matter seems to be an independent risk factor for dementia. The finding adds to evidence suggesting that preventing hypertension helps protect against dementia. High blood pressure is common in the U.S.

A large meta-analysis has concluded that having diabetes increases the chance that a person with mild cognitive impairment will progress to dementia by 65%.

There was no consistent evidence that hypertension or cholesterol levels increased the risk of someone with MCI progressing to dementia. Smoking was similarly not associated with increased risk, although the reason for this probably lies in mortality: smokers tend to die before developing dementia.

Memory tests predict brain atrophy and Alzheimer's disease

Data from the Alzheimer's Disease Neuroimaging Initiative (ADNI), involving 230 cognitively normal individuals and 394 individuals with diagnosed with MCI on the basis of one episodic test, has found that performance on two tests markedly improved the identification of those whose MCI was more serious.

MCI can be a step on the road to Alzheimer's, but it can also be a reversible condition, and it’s obviously helpful to be able to distinguish the two.

A long-running study comparing African-Americans and Nigerians has found the incidence of dementia has fallen significantly over two decades among the African-Americans, but remained the same for the Nigerians (for whom it was lower anyway).

The study enrolled two cohorts, one in 1992 and one in 2001, who were evaluated every 2–3 years until 2009. The 1992 cohort included 1440 older African-Americans (70+) and 1774 Nigerian Yoruba; the 2001 cohort included 1835 African-Americans and 1895 Yoruba. None of the participants had dementia at study beginning.

Optimal levels of cardiovascular health in older age associated with lower dementia risk

A French study involving 6,626 older adults (65+) found that having optimal levels in more measures of cardiovascular health (nonsmoking, weight, diet, physical activity, cholesterol, blood glucose and blood pressure) was associated with lower dementia risk and slower rates of cognitive decline. Dementia risk and rates of cognitive decline lowered with each additional metric at the recommended optimal level.

A large study using data from the famous Framingham Heart Study has compared changes in dementia onset over the last three decades. The study found that over time the age of onset has increased while the length of time spent with dementia has decreased.

A clinical trial involving 9361 older adults (50+) with hypertension but without diabetes or history of stroke has found that intensive control of blood pressure significantly reduced the risk of developing mild cognitive impairment.

While there was also a 15% reduction in dementia, this result did not reach statistical significance. This may have been due to the small number of new cases of dementia in the study groups.