Latest Research News
Brain scans of 9,772 people aged 44 to 79, who were enrolled in the UK Biobank study, have revealed that smoking, high blood pressure, high pulse pressure, diabetes, and high BMI — but not high cholesterol — were all linked to greater brain shrinkage, less grey matter and less healthy white matter.
Smoking, high blood pressure, and diabetes were the most important factors, but there was also a compound effect, with the number of vascular risk factors being associated with greater damage to the brain. On average, those with the highest vascular risk had nearly 3% less volume of grey matter, and one-and-a-half times the damage to their white matter, compared to people who had the lowest risk.
The brain regions affected were mainly those involved in ‘higher-order’ thinking, and those known to be affected early in the development of dementia.
The associations were as strong for middle-aged adults as for older ones, suggesting the importance of tackling these factors early.
While the effect size was small, the findings emphasize how vulnerable the brain is to vascular factors even in relatively healthy adults. This also suggests the potential of lifestyle changes for fighting cognitive decline.
Although this study didn't itself examine cognitive performance in its participants, other studies have shown links between cognitive impairment and vascular risk factors, particularly diabetes, obesity, hypertension, and smoking.
Cognitive decline in type 2 diabetes linked to white matter hyperintensities
While type 2 diabetes has been associated with cognitive problems, the mechanism has been unclear. Now a study involving 93 people with type 2 diabetes has found that greater white matter hyperintensities (indicative of cerebral small vessel disease) were associated with decreased processing speed (but not with memory or executive function).
Cox, Simon R. et al. 2019. Associations between vascular risk factors and brain MRI indices in UK Biobank. European Heart Journal. doi:10.1093/eurheartj/ehz100
(2018). Cognitive functioning and structural brain abnormalities in people with Type 2 diabetes mellitus.
Diabetic Medicine. 35(12), 1663 - 1670.
As we all know, people are living longer and obesity is at appalling levels. For both these (completely separate!) reasons, we expect to see growing rates of dementia. A new analysis using data from the long-running Framingham Heart Study offers some hope to individuals, however.
Looking at the rate of dementia during four distinct periods in the late 1970s, late 1980s, 1990s, and 2000s, using data from 5205 older adults (60+), the researchers found that there was a progressive decline in the incidence of dementia at a given age, with an average reduction of 20% per decade since the 1970s (22%, 38%, and 44% during the second, third, and fourth epochs, respectively).
There are two important things to note about this finding:
- the decline occurred only in people with a high school education and above
- the decline was more pronounced with dementia caused by vascular diseases, such as stroke.
The cumulative risk over five years, adjusted for age and gender, were:
- 3.6 per 100 persons during the first period (late 1970s and early 1980s)
- 2.8 per 100 persons during the second period (late 1980s and early 1990s)
- 2.2 per 100 persons during the third period (late 1990s and early 2000s)
- 2.0 per 100 persons during the fourth period (late 2000s and early 2010s).
Part of the reason for the decline is put down to the decrease in vascular risk factors other than obesity and diabetes, and better management of cardiovascular diseases and stroke. But this doesn't completely explain the decrease. I would speculate that other reasons might include:
- increased mental stimulation
- improvements in lifestyle factors such as diet and exercise
- better health care for infectious and inflammatory conditions.
The finding is not completely unexpected. Recent epidemiological studies in the U.S., Canada, England, the Netherlands, Sweden and Denmark have all suggested that “a 75- to 85-year-old has a lower risk of having Alzheimer’s today than 15 or 20 years ago.” Which actually cuts to the heart of the issue: individual risk of dementia has gone down (for those taking care of their brain and body), but because more and more people are living longer, the numbers of people with dementia are increasing.
(2016). Incidence of Dementia over Three Decades in the Framingham Heart Study.
New England Journal of Medicine. 374(6), 523 - 532.
Blood pressure data from 378 participants in the Framingham Heart Study has revealed that those who had high systolic blood pressure when they were 50-60 years old scored worse on a working memory test 30 years later. However, an association with verbal fluency was only significant for those with the 'Alzheimer's' APOe4 gene.
The finding adds to increasing evidence that managing health conditions such as cardiovascular health, diabetes, and hypertension, in midlife is important for cognitive health in old age, but tempers the message by suggesting that effects may be quite specific, with some applying mainly to those who are genetically vulnerable.
Nishtala A, Himali JJ, Beiser A, Murabito JM, Seshadri S, Wolf PA, Au R (2015) Midlife Hypertension Risk and Cognition in the Non-Demented Oldest Old: Framingham Heart Study. J Alzheimers Dis 47, 197-204.
Brain scans of 61 older adults (65-90), of whom 30 were cognitively healthy, 24 cognitively impaired and 7 diagnosed with dementia, found that, across all groups, both memory and executive function correlated negatively with brain infarcts, many of which had been clinically silent. The level of amyloid in the brain did not correlate with either changes in memory or executive function, and there was no evidence that amyloid interacted with infarcts to impair thinking.
Bottom line: vascular brain injury was far more important than amyloid burden for memory and executive function. The finding highlights the role of vascular injury in mild cognitive impairment.
(2013). The aging brain and cognition: Contribution of vascular injury and aβ to mild cognitive dysfunction.
JAMA Neurology. 1 - 8.
I’ve reported before on the evidence suggesting that carriers of the ‘Alzheimer’s gene’, APOE4, tend to have smaller brain volumes and perform worse on cognitive tests, despite being cognitively ‘normal’. However, the research hasn’t been consistent, and now a new study suggests the reason.
The e4 variant of the apolipoprotein (APOE) gene not only increases the risk of dementia, but also of cardiovascular disease. These effects are not unrelated. Apoliproprotein is involved in the transportation of cholesterol. In older adults, it has been shown that other vascular risk factors (such as elevated cholesterol, hypertension or diabetes) worsen the cognitive effects of having this gene variant.
This new study extends the finding, by looking at 72 healthy adults from a wide age range (19-77).
Participants were tested on various cognitive abilities known to be sensitive to aging and the effects of the e4 allele. Those abilities include speed of information processing, working memory and episodic memory. Blood pressure, brain scans, and of course genetic tests, were also performed.
There are a number of interesting findings:
- The relationship between age and hippocampal volume was stronger for those carrying the e4 allele (shrinkage of this brain region occurs with age, and is significantly greater in those with MCI or dementia).
- Higher systolic blood pressure was significantly associated with greater atrophy (i.e., smaller volumes), slower processing speed, and reduced working memory capacity — but only for those with the e4 variant.
- Among those with the better and more common e3 variant, working memory was associated with lateral prefrontal cortex volume and with processing speed. Greater age was associated with higher systolic blood pressure, smaller volumes of the prefrontal cortex and prefrontal white matter, and slower processing. However, blood pressure was not itself associated with either brain atrophy or slower cognition.
- For those with the Alzheimer’s variant (e4), older adults with higher blood pressure had smaller volumes of prefrontal white matter, and this in turn was associated with slower speed, which in turn linked to reduced working memory.
In other words, for those with the Alzheimer’s gene, age differences in working memory (which underpin so much of age-related cognitive impairment) were produced by higher blood pressure, reduced prefrontal white matter, and slower processing. For those without the gene, age differences in working memory were produced by reduced prefrontal cortex and prefrontal white matter.
Most importantly, these increases in blood pressure that we are talking about are well within the normal range (although at the higher end).
The researchers make an interesting point: that these findings are in line with “growing evidence that ‘normal’ should be viewed in the context of individual’s genetic predisposition”.
What it comes down to is this: those with the Alzheimer’s gene variant (and no doubt other genetic variants) have a greater vulnerability to some of the risk factors that commonly increase as we age. Those with a family history of dementia or serious cognitive impairment should therefore pay particular attention to controlling vascular risk factors, such as hypertension and diabetes.
This doesn’t mean that those without such a family history can safely ignore such conditions! When they get to the point of being clinically diagnosed as problems, then they are assuredly problems for your brain regardless of your genetics. What this study tells us is that these vascular issues appear to be problematic for Alzheimer’s gene carriers before they get to that point of clinical diagnosis.
(Submitted). Age-Related Differences in Memory and Executive Functions in Healthy APOE ɛ4 Carriers: The Contribution of Individual Differences in Prefrontal Volumes and Systolic Blood Pressure.
Neuropsychologia. 50(5), 704 - 714.
Damage to the retina (retinopathy) doesn’t produce noticeable symptoms in the early stages, but a new study indicates it may be a symptom of more widespread damage. In the ten-year study, involving 511 older women (average age 69), 7.6% (39) were found to have retinopathy. These women tended to have lower cognitive performance, and brain scans revealed that they had more areas of small vascular damage within the brain — 47% more overall, and 68% more in the parietal lobe specifically. They also had more white matter damage. They did not have any more brain atrophy.
These correlations remained after high blood pressure and diabetes (the two major risk factors for retinopathy) were taken into account. It’s estimated that 40-45% of those with diabetes have retinopathy.
Those with retinopathy performed similarly to those without on a visual acuity test. However, testing for retinopathy is a simple test that should routinely be carried out by an optometrist in older adults, or those with diabetes or hypertension.
The findings suggest that eye screening could identify developing vascular damage in the brain, enabling lifestyle or drug interventions to begin earlier, when they could do most good. The findings also add to the reasons why you shouldn’t ignore pre-hypertensive and pre-diabetic conditions.
(2012). Cognitive Function and Retinal and Ischemic Brain Changes The Women's Health Initiative.
Neurology. 78(13), 942 - 949.
The study involved 104 healthy older adults (average age 87) participating in the Oregon Brain Aging Study. Analysis of the nutrient biomarkers in their blood revealed that those with diets high in omega 3 fatty acids and in vitamins C, D, E and the B vitamins had higher scores on cognitive tests than people with diets low in those nutrients, while those with diets high in trans fats were more likely to score more poorly on cognitive tests.
These were dose-dependent, with each standard deviation increase in the vitamin BCDE score ssociated with a 0.28 SD increase in global cognitive score, and each SD increase in the trans fat score associated with a 0.30 SD decrease in global cognitive score.
Trans fats are primarily found in packaged, fast, fried and frozen food, baked goods and margarine spreads.
Brain scans of 42 of the participants found that those with diets high in vitamins BCDE and omega 3 fatty acids were also less likely to have the brain shrinkage associated with Alzheimer's, while those with high trans fats were more likely to show such brain atrophy.
Those with higher omega-3 scores also had fewer white matter hyperintensities. However, this association became weaker once depression and hypertension were taken into account.
Overall, the participants had good nutritional status, but 7% were deficient in vitamin B12 (I’m surprised it’s so low, but bear in mind that these are already a select group, being healthy at such an advanced age) and 25% were deficient in vitamin D.
The nutrient biomarkers accounted for 17% of the variation in cognitive performance, while age, education, APOE genotype (presence or absence of the ‘Alzheimer’s gene’), depression and high blood pressure together accounted for 46%. Diet was more important for brain atrophy: here, the nutrient biomarkers accounted for 37% of the variation, while the other factors accounted for 40% (meaning that diet was nearly as important as all these other factors combined!).
The findings add to the growing evidence that diet has a significant role in determining whether or not, and when, you develop Alzheimer’s disease.
(2012). Nutrient biomarker patterns, cognitive function, and MRI measures of brain aging.
Neurology. 78(4), 241 - 249.
In the last five years, three studies have linked lower neighborhood socioeconomic status to lower cognitive function in older adults. Neighborhood has also been linked to self-rated health, cardiovascular disease, and mortality. Such links between health and neighborhood may come about through exposure to pollutants or other environmental stressors, access to alcohol and cigarettes, barriers to physical activity, reduced social support, and reduced access to good health and social services.
Data from the large Women’s Health Initiative Memory Study has now been analyzed to assess whether the relationship between neighborhood socioeconomic status can be explained by various risk and protective factors for poor cognitive function.
Results confirmed that higher neighborhood socioeconomic status was associated with higher cognitive function, even after individual factors such as age, ethnicity, income, education, and marital status have been taken into account. A good deal of this was explained by vascular factors (coronary heart disease, diabetes, stroke, hypertension), health behaviors (amount of alcohol consumed, smoking, physical activity), and psychosocial factors (depression, social support). Nevertheless, the association was still (barely) significant after these factors were taken account of, suggesting some other factors may also be involved. Potential factors include cognitive activity, diet, and access to health services.
In contradiction of earlier research, the association appeared to be stronger among younger women. Consistent with other research, the association was stronger for non-White women.
Data from 7,479 older women (65-81) was included in the analysis. Cognitive function was assessed by the Modified MMSE (3MSE). Neighborhood socioeconomic status was assessed on the basis of: percentage of adults over 25 with less than a high school education, percentage of male unemployment, percentage of households below the poverty line, percentage of households receiving public assistance, percentage of female-headed households with children, and median household income. Around 87% of participants were White, 7% Black, 3% Hispanic, and 3% other. Some 92% had graduated high school, and around 70% had at least some college.
(2011). Neighborhood Socioeconomic Status and Cognitive Function in Women.
Am J Public Health. 101(9), 1721 - 1728.
Lang IA, Llewellyn DJ, Langa KM, Wallace RB, Huppert FA, Melzer D. 2008. Neighborhood deprivation, individual socioeconomic status, and cognitive function in older people: analyses from the English Longitudinal Study of Ageing. J Am Geriatr Soc., 56(2), 191-198.
Sheffield KM, Peek MK. 2009. Neighborhood context and cognitive decline in older Mexican Americans: results from the Hispanic Established Populations for Epidemiologic Studies of the Elderly. Am J Epidemiol., 169(9), 1092-1101.
Wight RG, Aneshensel CS, Miller-Martinez D, et al. 2006. Urban neighborhood context, educational attainment, and cognitive function among older adults. Am J Epidemiol., 163(12), 1071-1078.
Growing evidence links obesity and poorer cognitive performance. Many factors associated with obesity, such as high blood pressure, type 2 diabetes and sleep apnea, damage the brain.
A study involving109 bariatric surgery patients and 41 obese control subjects has found that the bariatric surgery patients demonstrated improved memory and concentration 12 weeks after surgery, improving from the slightly impaired range to the normal range. That of the obese controls actually declined over this period. The improvement of those who had surgery seemed to be particularly related to improved blood pressure.
Study participants will be tested one year and two years after surgery.
(2010). Improved memory function 12 weeks after bariatric surgery.
Surgery for Obesity and Related Diseases.
Lesions of the brain microvessels include white-matter hyperintensities and the much less common silent infarcts leading to loss of white-matter tissue. White-matter hyperintensities are common in the elderly, and are generally regarded as ‘normal’ (although a recent study suggested we should be less blasé about them — that ‘normal’ age-related cognitive decline reflects the presence of these small lesions). However, the degree of white-matter lesions is related to the severity of decline (including increasing the risk of Alzheimer’s), and those with hypertension or diabetes are more likely to have a high number of them.
A new study has investigated the theory that migraines might also lead to a higher number of white-matter hyperintensities. The ten-year French population study involved 780 older adults (65+; mean age 69). A fifth of the participants (21%) reported a history of severe headaches, of which 71% had migraines.
Those with severe headaches were twice as likely to have a high quantity of white-matter hyperintensities as those without headaches. However, there was no difference in cognitive performance between the groups. Those who suffered from migraines with aura (2% of the total), also showed an increased number of silent cerebral infarcts — a finding consistent with other research showing that people suffering from migraine with aura have an increased risk of cerebral infarction (or strokes). But again, no cognitive decline was observed.
The researchers make much of their failure to find cognitive impairment, but I would note that, nevertheless, the increased number of brain lesions does suggest that, further down the track, there is likely to be an effect on cognitive performance. Still, headache sufferers can take comfort in the findings, which indicate the effect is not so great that it shows up in this decade-long study.
(2011). Headache, migraine, and structural brain lesions and function: population based Epidemiology of Vascular Ageing-MRI study.
BMJ. 342(jan18 2), c7357-c7357 - c7357-c7357.
Research into the link, if any, between cholesterol and dementia, has been somewhat contradictory. A very long-running Swedish study may explain why. The study, involving 1,462 women aged 38-60 in 1968, has found that cholesterol measured in middle or old age showed no link to dementia, but there was a connection between dementia and the rate of decline in cholesterol level. Those women whose cholesterol levels decreased the most from middle to older age were more than twice as likely to develop dementia as those whose cholesterol levels increased or stayed the same (17.5% compared to 8.9%).After 32 years, 161 women had developed dementia.
Later in life, women with slightly higher body mass index, higher levels of cholesterol and higher blood pressure tend to be healthier overall than those whose weight, cholesterol and blood pressure are too low. But it is unclear whether "too low" cholesterol, BMI and blood pressure are risk factors for dementia or simply signs that dementia is developing, for reasons we do not yet understand.
On the other hand, a recent rat study has found that consuming a high cholesterol diet for five months caused memory impairment, cholinergic dysfunction, inflammation, enhanced cortical beta-amyloid and tau and induced microbleedings — all of which is strikingly similar to Alzheimer's pathology. And this finding is consistent with a number of other studies. So it does seem clear that the story of how exactly cholesterol impacts Alzheimer’s is a complex one that we are just beginning to unravel.
In light of other research indicating that the response of men and women to various substances (eg caffeine) may be different, we should also bear in mind that the results of the Swedish study may apply only to women.
(2010). The 32-year relationship between cholesterol and dementia from midlife to late life.
Neurology. 75(21), 1888 - 1895.
(2010). Hypercholesterolemia in rats impairs the cholinergic system and leads to memory deficits.
Molecular and Cellular Neuroscience. 45(4), 408 - 417.
Older news items (pre-2010) brought over from the old website
High blood pressure linked to memory problems in middle age
A study involving nearly 20,000 people age 45 and older, of whom nearly half were taking medication for high blood pressure, has found that those with high diastolic blood pressure (the bottom number of a blood pressure reading) were more likely to have cognitive impairment than those with normal diastolic readings. For every 10 point increase in the reading, the odds of a person having cognitive problems was 7% higher. There was no correlation with systolic blood pressure. The results were adjusted for age, smoking status, exercise level, education, diabetes and high cholesterol. High diastolic blood pressure is known to lead to weakening of small arteries in the brain.
(2009). Association of higher diastolic blood pressure levels with cognitive impairment.
Neurology. 73(8), 589 - 595.
A diet that may reduce age-related cognitive decline
The Dietary Approaches to Stop Hypertension (DASH) diet lowers blood pressure and is often recommended by physicians to people with high blood pressure or pre-hypertension. An 11-year study of over 3800 seniors found that those with higher DASH diet adherence scores had higher cognitive scores at the beginning of the study and increasingly so over time. Four of the nine food-group/nutrient components were independently associated with cognitive scores -- vegetables, whole grains, low-fat dairy, nut/legumes. When a score based on just these four components was used, the difference between those in the highest quintile and those in the lowest was even greater, particularly by the end of the study.
Wengreen, H.J. et al. 2009. DASH diet adherence scores and cognitive decline and dementia among aging men and women: Cache County study of Memory Health and Aging. Presented at the Alzheimer's Association International Conference on Alzheimer's Disease July 11-16 in Vienna.
Factors helping you maintain cognitive function in old age
An 8-year study of over 2,500 seniors in their 70s, has found that 53% showed normal age-related decline, 16% showed major cognitive decline, and an encouraging 30% had no change or improved on the tests over the years. The most important factors in determining whether a person maintained their cognitive health was education and literacy: those with a ninth grade literacy level or higher were nearly five times as likely to stay sharp than those with lower literacy levels; those with at least a high school education were nearly three times as likely to stay sharp as those who have less education. Lifestyle factors were also significant: non-smokers were nearly twice as likely to stay sharp as smokers; those who exercised moderately to vigorously at least once a week were 30% more likely to maintain their cognitive function than those who do not exercise that often; people working or volunteering and people who report living with someone were 24% more likely to maintain cognitive function.
(2009). Predictors of maintaining cognitive function in older adults: The Health ABC Study.
Neurology. 72(23), 2029 - 2035.
Hypertension in children linked to cognitive problems
A study of 32 newly diagnosed hypertensive children and adolescents (10 to 18 years old) plus 32 matched children with normal blood pressure has revealed that, according to parental assessment, those with high blood pressure scored significantly lower on executive function — that is, were poorer at planning, at complicated goal-directed tasks, and had more working memory problems. Additionally, more than half the children with both hypertension and obesity demonstrated clinically significant anxiety and depression.
Lande, M.B. et al. 2009. Parental Assessments of Internalizing and Externalizing Behavior and Executive Function in Children with Primary Hypertension. Journal of Pediatrics, 154 (2), 207-212.
High blood pressure may make it difficult for the elderly to think clearly
A study involving 36 community-dwelling elderly (60-87 years old) whose blood pressure and cognitive functioning was monitored for 60 days has found that those with high blood pressure tended to perform more poorly on one of the three cognitive tasks, and this was particularly so when their blood pressure was higher than normal. The finding suggests that high blood pressure impacts on inductive reasoning, and thus the ability to work flexibly with unfamiliar information and find solutions. It also suggests that, for those with high blood pressure, such reasoning will be particularly difficult when they are stressed.
Gamaldo, A.A., Weatherbee, S.R. & Allaire, J.C. 2008. Exploring the Within-Person Coupling of Blood Pressure and Cognition in Elders. Journal of Gerontology: Psychological Science, 63, 386-389.
High blood pressure associated with risk for mild cognitive impairment
A study of nearly 1000 older adults (average age 76.3) without mild cognitive impairment at the start of the study found that over the follow-up period (average: 4.7 years), 334 individuals developed mild cognitive impairment, of which 160 were amnestic (reduced memory) and 174 were non-amnestic. Hypertension (high blood pressure) was associated with an increased risk of non-amnestic mild cognitive impairment; but not with amnestic mild cognitive impairment.
(2007). Hypertension and the Risk of Mild Cognitive Impairment.
Arch Neurol. 64(12), 1734 - 1740.
Memory tasks require more coordinated brain blood flow for people with high blood pressure
Previous studies have found an association between high blood pressure and cognitive decline in older adults, but the evidence hasn’t been entirely consistent. Now a new study helps explain why the situation is not entirely straightforward. It appears that people with high blood pressure required more blood flow to the parts of the brain that support memory function than those with normal blood pressure. Moreover, and surprisingly, it turned out that antihypertensive medication actually made it worse, increasing the inefficiency of the brain’s work during memory tasks.
The findings were reported at the American Heart Association’s 61st Annual Fall Conference of the Council for High Blood Pressure Research.
Lowering blood pressure doesn't prevent cognitive impairment, dementia
A review of three large-scale studies of patients with hypertension who were treated with either medication or lifestyle strategies found no convincing evidence that lowering blood pressure prevents the development of dementia or cognitive impairment in hypertensive patients without apparent prior cerebrovascular disease. However, there is some evidence that midlife hypertension but not late life hypertension is related to cognitive decline; these studies involved patients aged 60 and older.
McGuiness, B., et al. The effects of blood pressure lowering on development of cognitive impairment and dementia in patients without apparent prior cerebrovascular disease. The Cochrane Database of Systematic Reviews 2006, Issue 2.
Review supports link between lifestyle factors and cognitive function in older adults
A review of 96 papers involving 36 very large, ongoing epidemiological studies in North America and Europe looking at factors involved in maintaining cognitive and emotional health in adults as they age has concluded that controlling cardiovascular risk factors, such as reducing blood pressure, reducing weight, reducing cholesterol, treating (or preferably avoiding) diabetes, and not smoking, is important for maintaining brain health as we age. The link between hypertension and cognitive decline was the most robust across studies. They also found a consistent close correlation between physical activity and brain health. However, they caution that more research is needed before specific recommendations can be made about which types of exercise and how much exercise are beneficial. They also found protective factors most consistently reported for cognitive health included higher education level, higher socio-economic status, emotional support, better initial performance on cognitive tests, better lung capacity, more physical exercise, moderate alcohol use, and use of vitamin supplements. Psychosocial factors, such as social disengagement and depressed mood, are associated with both poorer cognitive and emotional health in late life. Increased mental activity throughout life, such as learning new things, may also benefit brain health.
(2006). The NIH Cognitive and Emotional Health ProjectReport of the Critical Evaluation Study Committee.
Alzheimer's and Dementia. 2(1), 12 - 32.
Uncontrolled high blood pressure means more cognitive problems in old age
A study involving a subset of men (average age 67 years) in the VA Normative Aging Study has found that those men with uncontrolled hypertension performed significantly worse on tests of verbal fluency and short-term memory. Those whose hypertension was controlled did as well as those with normal blood pressure. In the United States, hypertension affects 60% of adults age 60 and older, and a high proportion of these are untreated or inadequately treated.
Brady, C.B., Spiro, A. III & Gaziano, J.M. 2005. Effects of Age and Hypertension Status on Cognition: The Veterans Affairs Normative Aging Study. Neuropsychology, 19 (6).
High blood pressure has stronger effect on cognitive function in African-Americans
Analysis of a large longitudinal study (the Maine-Syracuse Longitudinal Study 1976—2002) has found significant associations of high blood pressure to lower cognitive performance in the areas of abstract reasoning, psychomotor skills and visual organization skills. This association, moreover, was significantly greater for African-Americans, although it should be noted that there were only 147 African-Americans among the 1,563 participants. The effect was independent of age.
(2005). Blood pressure and cognitive function in an African-American and a Caucasian-American sample: the Maine-Syracuse Study.
Psychosomatic Medicine. 67(5), 707 - 714.
High blood pressure may be a factor in "senior moments"
An imaging study of seniors (average age 60) found that those with high blood pressure showed reduced blood flow to active brain areas when performing various everyday memory tasks, such as looking up a phone number then walking to another room to pick up the phone and dial the number. The diminished blood flow correlated to slightly worse scores on the memory tests. The differences weren’t large, but may help account for "senior moments" - memory problems commonly associated with age. It’s estimated that as many as a third of those with high blood pressure are not aware they have it.
Jennings, J.R., Muldoon, M.F., Meltzer, C.C., Ryan, C. & Price, J. 2003. Human Cerebral Blood Flow Responses to Information Processing Tasks are Decreased in Hypertensives Relative to Normotensives. Report presented at the American Heart Association's 57th Annual High Blood Pressure Research Conference, September 23.
Effects of high blood pressure on cognition may have been overstated
Epidemiological studies have suggested hypertensive patients perform worse than individuals with normal blood pressure on cognition tests. A new study has investigated performance on specific cognitive tasks (visual and memory search involving computer displays) by those with high blood pressure who were not on medication and had no detectable cardiovascular disease. Participants ranged in age from 20 to 80. Contrary to expectation, high blood pressure slowed performance only in the middle-aged group (40-59), not in those younger or older.
Madden, D., Langley, L., Thurston, R., Whiting, W. & Blumenthal, J. 2003. Interaction of Blood Pressure and Adult Age in Memory Search and Visual Search Performance. Aging, Neuropsychology and Cognition, 10 (4), 241-54.
Treatment to lower blood pressure reduces risk of cognitive decline in stroke patients
High blood pressure and stroke are associated with increased risks of dementia and cognitive impairment. In a study aimed to determine whether blood pressure lowering would reduce the risks of dementia and cognitive decline among individuals with cerebrovascular disease, 6105 people with prior stroke or transient ischemic attack were given either active treatment (perindopril for all participants and indapamide for those with neither an indication for nor a contraindication to a diuretic) or matching placebo(s). Over some 4 years, dementia was found in 6.3% of those given active treatment and 7.1% of those in the placebo group. Cognitive decline occurred in 9.1% of the actively treated group and 11.0% of the placebo group. The researchers concluded that blood pressure lowering with perindopril and indapamide therapy was helpful for those with cerebrovascular disease, in terms of reduced risks of dementia and cognitive decline.
(2003). Effects of Blood Pressure Lowering With Perindopril and Indapamide Therapy on Dementia and Cognitive Decline in Patients With Cerebrovascular Disease.
Arch Intern Med. 163(9), 1069 - 1075.
Age-related changes in the brain's white matter affect cognitive function
From around age 60, "white-matter lesions" appear in the brain, significantly affecting cognitive function. But without cognitive data from childhood, it is hard to know how much of the difference in cognitive abilities between elderly individuals is due to aging. A longitudinal study has been made possible by the Scottish Mental Survey of 1932, which gave 11-year-olds a validated cognitive test. Scottish researchers have tracked down healthy living men and women who took part in this Survey and retested 83 participants. Testing took place in 1999, when most participants were 78 years old.
It was found that the amount of white-matter lesions made a significant contribution to general cognitive ability differences in old age, independent of prior ability. The amount of white-matter lesions contributed 14.4% of the variance in cognitive scores; early IQ scores contributed 13.7%. The two factors were independent.
Although white-matter lesions are viewed as a normal part of aging, they are linked with other health problems, in particular to circulatory problems (including hypertension, diabetes, heart disease and cardiovascular risk factors).
(2003). Cerebral white matter abnormalities and lifetime cognitive change: a 67-year follow-up of the Scottish Mental Survey of 1932.
Psychology and Aging. 18(1), 140 - 148.
Sunflower seeds helpful in reducing hypertension and associated cognitive impairment
Research in rats has found that linoleic acid improved not only blood pressure, but also hypertension-induced memory decline, suggesting that the early incorporation of linoleic acid in the diet, may not only help in controlling hypertension, but may also improve hypertension-induced cognitive impairment. Linoleic acid is found in vegetable seed oils, such as safflower, sunflower, and hemp seed.
Holloway, V. 2002. Effects of early nutritional supplementation of linoleic acid in Hypertension. Paper presented at an American Physiological Society (APS) conference, "The Power of Comparative Physiology: Evolution, Integration and Application", August 24-28 in San Diego, CA.
High blood pressure increases risk of cognitive decline in older adults
A large-scale six-year study of people aged 40 to 70 years old found that people with diabetes and high blood pressure are more likely to experience cognitive decline. Diabetes was associated with greater cognitive decline for those younger than 58 as well as those older than 58, but high blood pressure was a risk factor only for the 58 and older group.
(2001). Cardiovascular risk factors and cognitive decline in middle-aged adults.
Neurology. 56(1), 42 - 48.
Untreated hypertension linked to severe cognitive decline in older adults
A large-scale study of French people aged 59 to 71 found that, after four years, 21.7% of those with untreated high blood pressure experienced severe cognitive decline. Of those with high blood pressure whose treatment didn't bring the blood pressure down to normal, 12.5% had severe cognitive decline. Of those whose high blood pressure was successfully treated, 7.8% had severe cognitive decline. Only 7.3% of those with normal blood pressure had severe cognitive decline.
Tzourio, C., Dufouil, C., Ducimetière, P., Alpérovitch, A. and for the EVA Study Group. 1999. Cognitive decline in individuals with high blood pressure: A longitudinal study in the elderly. Neurology, 53, 1948.