seniors

Smoking, hypertension, diabetes & obesity each linked to poor brain health

  • A large study has found that smoking, high blood pressure, diabetes, and obesity are each linked to more brain atrophy, and damage to white matter.
  • The more of these you have, the greater the shrinkage and damage.

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.

https://www.eurekalert.org/pub_releases/2019-03/esoc-shb030719.php

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).

https://www.eurekalert.org/pub_releases/2018-09/w-rem091818.php

Reference: 

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

[4395] Mankovsky, B., Zherdova N., van den Berg E., Biessels G.-J., & de Bresser J.
(2018).  Cognitive functioning and structural brain abnormalities in people with Type 2 diabetes mellitus.
Diabetic Medicine. 35(12), 1663 - 1670.

 

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Air pollution substantially reduces cognitive ability in older adults

  • A very large study shows that greater exposure to air pollution was linked to poorer cognitive performance in older adults, especially men and the less educated.

A large Chinese study involving 20,000 people has found that the longer people were exposed to air pollution, the worse their cognitive performance in verbal and math tests. The effect of air pollution on verbal tests became more pronounced with age, especially for men and the less educated.

The study followed the participants from 2010 to 2014, meaning that the same individuals could be assessed as air pollution varied from one year to the next.

The findings add to previous research showing the harmful effects of air pollution on cognitive performance in children.

https://www.theguardian.com/environment/2018/aug/27/air-pollution-causes-huge-reduction-in-intelligence-study-reveals

Reference: 

Xin Zhang, Xi Chen, Xiaobo Zhang. 2018. The impact of exposure to air pollution on cognitive performance. Proceedings of the National Academy of Sciences Sep 2018, 115 (37) 9193-9197; DOI: 10.1073/pnas.1809474115

 

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Depression linked to faster cognitive decline in older adults

  • A review of 34 studies confirms depression is linked to faster cognitive decline in older adults.

A review of 34 longitudinal studies, involving 71,244 older adults, has concluded that depression is associated with greater cognitive decline.

The study included people who presented with symptoms of depression as well as those that were diagnosed as clinically depressed, but excluded any who were diagnosed with dementia at the start of study.

Previous research has found that depression is associated with an increased dementia risk.

The researchers recommend that preventative measures such as exercising, practicing mindfulness, and undertaking recommended therapeutic treatments, such as Cognitive Behaviour Therapy, might help protect cognitive health.

While the review included some studies into anxiety, the numbers were insufficient to draw a conclusion.

https://www.eurekalert.org/pub_releases/2018-05/uos-dsu052318.php

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Fruit & veges slow memory decline in long-running study

  • A large, long-running study has found an association between consumption of fruit & vegetables and subjectively assessed memory skills in older men.

A study following nearly 28,000 older men for 20 years has found that regular consumption of leafy greens, dark orange and red vegetables and berry fruits, and orange juice, was associated with a lower risk of memory loss.

The study looked at 27,842 male health professionals, who were an average age of 51 in 1986, when the study began. Participants filled out questionnaires about how many servings of fruits, vegetables and other foods they had each day, at the beginning of the study and then every four years.

Specifically:

  • those who consumed the most vegetables (around six servings a day) were 34% less likely to develop poor thinking skills than the men who consumed the least amount of vegetables (around two servings)
  • 6.6% of men who consumed the most vegetables developed poor cognitive function, compared to 7.9% of men who consumed the least
  • those who drank orange juice every day were 47% less likely to develop poor thinking skills than those who drank less than one serving per month
  • 6.9% of men who drank orange juice every day developed poor cognitive function, compared to 8.4 % of men who drank orange juice less than once a month

Interestingly, those who ate larger amounts of fruits and vegetables 20 years earlier were less likely to develop cognitive problems, whether or not they kept eating larger amounts of fruits and vegetables about six years before the memory test.

Cognition was not, however, assessed objectively, nor was it tested at baseline. In 2008 and 2012, participants were given a short cognitive test to assess their subjective judgments of their memory and cognition. The brief test included such questions as:

  • "Do you have more trouble than usual remembering a short list of items, such as a shopping list?"
  • "Do you have more trouble than usual following a group conversation or a plot in a TV program due to your memory?"

Just over half the participants (55%) had good thinking and memory skills, 38% had moderate skills, and 7% had poor thinking and memory skills.

https://www.eurekalert.org/pub_releases/2018-11/aaon-ojl111918.php

Reference: 

Changzheng Yuan et al. 2019. Long-term intake of vegetables and fruits and subjective cognitive function in US men. Neurology, 92 (1) e63-e75.

 

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Poor sleep drives Alzheimer’s progression

  • Getting a good night’s sleep is given greater importance with the discovery that sleep deprivation appears to rapidly increase the spread of tau tangles.

Poor sleep has been associated with the development of Alzheimer's disease, and this has been thought to be in part because the protein amyloid beta increases with sleep deprivation. A new study explains more.

Experiments with mice show that sleep deprivation also rapidly increases levels of the other key Alzheimer’s disease protein, tau tangles.

The work built on findings that tau is high in older people who sleep poorly, and that, when people are kept awake all night, their tau levels rise by about 50%.

When mice had tau proteins seeded in the hippocampus of their brains, those who were kept awake for long periods each day (mice are nocturnal), showed significantly greater spread of tau tangles than those mice allowed to sleep normally. Moreover, the new tangles appeared in the same areas of the brain affected in people with Alzheimer’s.

Disrupted sleep also increased release of synuclein protein, a hallmark of Parkinson’s disease. People with Parkinson’s—like those with Alzheimer’s—often have sleep problems.

All of this supports the idea that sleep directly protects against the development of Alzheimer's.

https://www.futurity.org/alzheimers-disease-sleep-tau-1966962/

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Exercise improves brain function in older adults with MCI

  • A short exercise program improved cognition and brain blood flow in older adults with mild cognitive impairment.

A small study has found that a 12-week exercise program significantly improved cognition in both older adults with MCI and those who were cognitively healthy, but that effect on blood flow in the brain was different in these two groups.

While the exercise increased cerebral blood flow in the frontal cortex of those in the healthy group, those with MCI experienced decreases in cerebral blood flow. It has been speculated that the brain responds to early difficulties by increasing cerebral blood flow. This suggests that exercise may have the potential to reduce this compensatory blood flow and improve cognitive efficiency in those who are in the very early stages of Alzheimer's Disease.

The exercise training program consisted of four 30-minute sessions of moderate-intensity treadmill walking per week.

Both working memory and verbal fluency were tested (using the Rey Auditory Verbal Learning Test, and the Controlled Oral Word Association Test).

Changes in cerebral blood flow were measured in specific brain regions that are known to be involved in the pathogenesis of Alzheimer's disease, including the insula, the anterior cingulate cortex, and the inferior frontal gyrus.

Among those with MCI, decreased blood flow in the left insula and anterior cingulate cortex was strongly associated with improved verbal fluency.

https://www.eurekalert.org/pub_releases/2019-01/uom-usf013119.php

Reference: 

Alfini, A. J. et al. 2019. Resting Cerebral Blood Flow After Exercise Training in Mild Cognitive Impairment. Journal of Alzheimer's Disease, 67 (2), 671-684.

 

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Intensive hypertension treatment reduces risk of cognitive impairment

  • A large clinical trial comparing the effects on cardiovascular disease of standard blood pressure control vs stricter control, has found that stricter control significantly reduced the risk of mild cognitive impairment.

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.

Participants were randomly assigned to a systolic blood pressure goal of either less than 120 mm HG (intensive treatment) or less than 140 mm HG (standard treatment). They were then classified after five years as having no cognitive impairment, MCI or probable dementia.

The trial was stopped early due to its success in reducing cardiovascular disease. As a result, participants were on intensive blood pressure lowering treatment for a shorter period than originally planned. This impacted the number of cases of dementia occurring.

Hypertension affects more than half of Americans over age 50 and more than 75% of those older than 65.

https://www.eurekalert.org/pub_releases/2019-01/wfbm-lbp012419.php

Reference: 

The SPRINT MIND Investigators for the SPRINT Research Group. (2019). Effect of Intensive vs Standard Blood Pressure Control on Probable Dementia: A Randomized Clinical Trial. JAMA, 321(6), 553–561.

 

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Psychological distress a risk factor for dementia

  • A large Danish study has found that the greater number of symptoms of distress in late midlife, the more likely the individual was to develop dementia later in life.

Survey data from 6,807 Danish older adults (average age 60) in the Copenhagen City Heart Study, has found that being distressed in late midlife is associated with a higher risk of dementia in later life.

The survey measured “vital exhaustion”, which is operationalized as feelings of unusual fatigue, increased irritability and demoralization and can be considered an indicator of psychological distress. Vital exhaustion is suggested to be a response to unsolvable problems in individuals' lives, in particular when being incapable of adapting to prolonged exposure to stressors.

The study found a dose-response relation between symptoms of vital exhaustion reported in late midlife and the risk of dementia later in life:

  • for every additional symptom, dementia incidence increased by 2%
  • those reporting 5 to 9 symptoms had a 25% higher risk of dementia compared to those with no symptoms
  • those reporting 10 to 17 symptoms (the maximum) had a 40% higher risk of dementia compared with not having symptoms.

Results were adjusted for gender, marital status, lower educational level, lifestyle factors and comorbidities.

https://www.eurekalert.org/pub_releases/2019-01/ip-pdi011719.php

Full paper available at: https://content.iospress.com/articles/journal-of-alzheimers-disease/jad180478

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Poor sleep in older adults may increase Alzheimer’s risk

  • Older people who spend less time in slow-wave sleep (deep sleep) have higher levels of the Alzheimer’s brain protein tau.

Poor sleep has been associated with Alzheimer's disease risk, but a new study suggests a specific aspect of sleep is important.

The study, involving 119 older adults (60+), of whom 80% were cognitively normal and the remainder very mildly impaired, found that decreased slow-wave sleep coincided with higher levels of tau in the brain and a higher tau-to-amyloid ratio in the cerebrospinal fluid.

Amyloid plaques and tau tangles develop for decades before cognitive symptoms of dementia emerge. Identifying the process at an early stage offers a possible window of opportunity for successful intervention.

Participants’ sleep at home was monitored over the course of a normal week, and participants also kept sleep logs of nighttime sleep and daytime napping. Thirty-eight people underwent PET brain scans for amyloid-beta and tau proteins, and 104 people underwent spinal taps to provide cerebrospinal fluid. Twenty-seven did both.

Those with increased tau pathology actually slept more, during both night and day, but their quality of sleep was poorer. In fact, daytime napping alone was significantly associated with high levels of tau, making it a useful indicator of risk.

https://www.futurity.org/alzheimers-disease-sleep-1954732/

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Lower tau levels may obscure early Alzheimer’s in black patients

  • Two large studies show an association between the Alzheimer's protein tau and the Alzheimer's gene APOE4, but the association varies across race and gender.

Data from 1,215 older adults, of whom 173 (14%) were African-American, has found that, although brain scans showed no significant differences between black and white participants, cerebrospinal fluid (CSF) showed significantly lower levels of the brain protein tau in African-Americans.

While both groups showed the same (expected) pattern of higher tau levels being associated with greater chance of cognitive impairment, the absolute amounts of tau protein were consistently lower in African-Americans.

However, when APOE status was taken into account, it was found that those who held the low-risk variants of the “Alzheimer’s gene” had similar levels of tau, regardless of race. It was only African-Americans with the APOE4 gene variant that showed lower levels of tau.

This suggests that the APOE4 risk factor has different effects in African-Americans compared to non-Hispanic white Americans, and points to the need for more investigation into how Alzheimer’s develops in various populations.

Interestingly, another study, using data from 1798 patients (of whom 1690 were white), found that there was a strong gender difference in the association between APOE status and tau levels in the CSF.

Previous research has shown that the link between APOE4 and Alzheimer's is stronger in women than men. This study points to a connection with tau levels, as there was no gender difference in the association between APOE and amyloid-beta levels, amyloid plaques, or tau tangles.

https://www.futurity.org/alzheimers-disease-black-patients-1951502/

Reference: 

Morris JC, Schindler SE, McCue LM, et al. Assessment of Racial Disparities in Biomarkers for Alzheimer Disease. JAMA Neurol. Published online January 07, 2019. doi:10.1001/jamaneurol.2018.4249

Hohman TJ, Dumitrescu L, Barnes LL, et al. Sex-Specific Association of Apolipoprotein E With Cerebrospinal Fluid Levels of Tau. JAMA Neurol. 2018;75(8):989–998. doi:10.1001/jamaneurol.2018.0821

 

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