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  • A large long-running study found that stressful life experiences (but not traumatic events) during middle-age were associated with greater memory decline in later life — but only for women.
  • A large long-running study found that middle-aged adults with higher levels of the stress hormone cortisol had poorer cognition than those with average cortisol levels, and this was also associated with greater brain atrophy.
  • A study found that older adults (65-95) who responded to stressful events with more negative emotions showed greater fluctuations in cognitive performance.

Stressors in middle age linked to cognitive decline in older women

Data from some 900 older adults has linked stressful life experiences among middle-aged women, but not men, to greater memory decline in later life.

  • A large study indicates that visual impairment can play a role in age-related cognitive decline.

A study involving more than 2,500 older adults (65+) found that the rate of worsening vision was associated with the rate of cognitive decline. More importantly, vision has a stronger influence on cognition than the reverse.

  • A very large Taiwanese study found that adults with hearing loss had a higher dementia risk, and this was particularly so for those aged 45-64.
  • A very large Japanese study found that a dramatically greater proportion of older adults (65+) with hearing loss reported memory loss, compared to much fewer of those without hearing loss.
  • A very large study found that older adults (50+) who used hearing aids for hearing loss showed better performance on tests of working memory and attention compared with those who didn't use hearing aids for their hearing loss.
  • A large long-running study found that, while hearing impairment was associated with accelerated cognitive decline in older adults (mean age 73.5), the impact might be lessened by higher education.
  • A very large 8-year study found that hearing loss was associated with higher risk of subjective cognitive decline in older men (62+).
  • A very small study suggests that cognitive problems in some older adults may derive directly from hearing impairments, and may be fixed by addressing this.
  • A large, long-running study found that eating a healthy diet was associated with a lower risk of acquired hearing loss in women.

Hearing loss linked to increased dementia risk

  • A very large Canadian study found that older adults with chronic insomnia performed significantly worse on cognitive tests.
  • A small study links older adults' increasing difficulties with consolidating memories to poorer synchronization of brainwaves during sleep.
  • A fruitful study shows that oxidative stress drives sleep, and that this is regulated by a specific molecule that monitors the degree of oxidative stress.

Chronic insomnia linked to memory problems

  • Adults whose sleep quality declined in their 40s and 50s had more amyloid-beta in their brains later in life, while those reporting poorer sleep in their 50s and 60s had more tau tangles.
  • Greater tau protein was associated with less synchronized brainwaves during sleep.
  • Both amyloid-beta and tau levels increase dramatically after a single night of sleep deprivation, suggesting good sleep helps remove these proteins.
  • A large study found that older adults who consistently slept more than nine hours every night had twice the risk of developing dementia and Alzheimer’s disease within the next 10 years.
  • A large Japanese study found that those with sleep durations of less than 5 hours or more than 10 hours were more likely to develop dementia. However, those with short sleep could mitigate the effect with high physical activity.
  • A largish 12-year study found that poorer REM sleep was associated with an increased dementia risk.
  • Sleep apnea has been linked to higher levels of tau in the entorhinal cortex, poorer attention and memory, and slower processing speed.
  • Those with the APOE4 gene may be particularly vulnerable to the ill effects of sleep apnea.

Disrupted sleep in one's 50s, 60s raises Alzheimer's risk

  • A very large Korean study found older adults with chronic periodontitis had a 6% higher risk for dementia.
  • Two animal studies found that the bacteria involved in gum disease increases amyloid-beta, brain inflammation, and neuron death.

Periodontitis raises dementia risk

  • A large study finds those who go on to develop Alzheimer's show atrophy of the hippocampus before age 40, and in the amygdala around age 40.

Brain scans from over 4,000 people, across the age range (9 months to 94 years) and including 1,385 Alzheimer's patients, has revealed an early divergence between those who go on to develop Alzheimer’s and those who age normally.

  • Fruitflies genetically engineered to express amyloid-beta show that neuron loss is not always bad, but reflects the removal of defective neurons.

A fruitfly study suggests that losing neurons is not necessarily a bad thing.

  • A mobile phone game designed to test spatial navigation skills (Sea Hero Quest) has found that performance can distinguish APOE4 carriers from non-carriers.
  • Preliminary findings from a long-term study indicate that middle-aged adults with close relatives with Alzheimer's did worse on a test that measured their ability to visualise their position, and tended to have a smaller hippocampus.
  • A small study found that increasing difficulties with building cognitive maps of new surroundings was linked to Alzheimer's biomarkers. Difficulties in learning a new route appeared later, among those with early Alzheimer's.

Mobile game detects Alzheimer's risk

  • A study involving nearly 600 older adults found that using two different episodic memory tests markedly improved MCI diagnosis, compared with only using one.
  • A large study found that the clock drawing test was better than the MMSE in identifying cognitive impairment, and concludes it should be given to all patients with high blood pressure.
  • A largish study of middle-aged men confirmed that practice effects mask cognitive decline in those who have experience repeated testing.
  • A large study indicates that verb fluency is a better test than the more usual word fluency tests, and poorer verb fluency was linked to faster decline to MCI and progression from MCI to dementia.
  • A smallish study found that a brief, simple number naming test differentiates between cognitively healthy older adults and those with MCI or Alzheimer's 90% of the time.
  • A study involving 450 patients with memory problems found that those with anosognosia (unawareness of such problems) had higher rates of amyloid-beta clumps and were more likely to develop dementia in the next 2 years.
  • Another larger study found that those with anosognosia  had reduced glucose uptake in specific brain regions.
  • A new cognitive test that assesses relational memory has been found to be effective in distinguishing very early mild Alzheimer's from normal aging.

Memory tests predict brain atrophy and Alzheimer's disease

  • A study found an association in healthy older adults between higher amyloid beta levels and worsening anxiety.

Data from the Harvard Aging Brain Study found that higher amyloid beta levels were associated with increasing anxiety symptoms in cognitively normal older adults. The results suggest that worsening anxious-depressive symptoms may be an early predictor of elevated amyloid beta levels.

  • A new test can quickly detect reduced blood capillaries in the back of the eye that are an early indication of Alzheimer's, and shows that it can help distinguish Alzheimer's from MCI.

A study has shown new technology can quickly and non-invasively detect reduced blood capillaries in the back of the eye that are an early indication of Alzheimer's.

  • A long-running study found subtle cognitive deficits evident 11-15 years before clear impairment, as were changes in tau protein.

A very long-running study involving 290 people at risk of Alzheimer's has found that, in those 81 people who developed

  • A large study found that most of those who were very poor at identifying common odors developed dementia within 5 years.
  • A study of older adults with a parent who had Alzheimer's found that those who were poorest at identifying odors showed the most Alzheimer's biomarkers.
  • A largish study found that poorer odor identification in older adults (average age 80) )was associated with a transition to dementia and with cognitive decline.
  • An animal study found olfactory dysfunction precedes cognitive problems, and relates amyloid-beta protein in the olfactory epithelium.
  • A large 13-year study found that a poor sense of smell was linked to a greater risk of death within 10 years, and of death from dementia and Parkinson’s disease in particular.

A long-term study of nearly 3,000 older adults (57-85) has found that those who couldn’t identify at least four out of five common odors were more than twice as likely as those with a normal sense of smell to develop dementia within five years.

  • A blood-clotting protein called fibrinogen has been shown to provoke the brain's immune cells into destroying synapses. The process begins with fibrinogen leaking from the blood into the brain.
  • Another study has found that nearly half of all dementias begin with a breakdown of the gatekeeper cells (pericytes) that help keep fibrinogen out of the brain.

Alzheimer's disease is associated with abnormalities in the vast network of blood vessels in the brain, but it hasn’t been known how this affects cognition. A study has now shown that a blood-clotting protein called fibrinogen plays a part.

  • Blood flow deficits in the brain, seen early on in Alzheimer's, have now been linked to some capilleries being block by white blood cells.

It’s been known that decreased blood flow in the brain occurs in people with Alzheimer's, and recent studies suggest that brain blood flow deficits are one of the earliest detectable symptoms of dementia.

  • A study shows that blood is stored in the blood vessels in the space between the brain and skull, and its flow  is closely linked to the flow of cerebrospinal fluid in and out of the brain's ventricles.
  • A second study shows that capilleries, the smallest blood vessels in the brain, monitor the flow of blood within the brain and actively direct it to the areas that need it the most.

Increases in brain activity are matched by increases in blood flow. Neurons require a huge amount of energy, but can’t store it themselves, so must rely on blood to deliver the nutrients they need.

Two new studies help explain how blood flow is controlled.

  • Age-related changes in gene enhancers have been linked to faster cognitive decline in Alzheimer's brains.

New findings identify a mechanism that accelerates aging in the brain and gives rise to Alzheimer's disease.

  • A mouse study has shown that, as cells age, their ability to remove damaged proteins and structures (autophagy) declines, due to a decrease in the cell components (autophagosomes) that collect the damaged proteins.
  • A study found that the process of breaking down defective mitochondria and recycling the components (mitophagy) is impaired in those with Alzheimer's.
  • Microglia clear damage by engulfing the damaged matter then releasing it inside exosomes, which can be absorbed by other cells. Studies have now shown that these exosomes, designed to transmit information, can also spread harmful tau & amyloid-beta protein.
  • A mouse study has shown how amyloid plaques lead to tau tangles, and that weakened microglia facilitate this. It also links weak microglia to the risky variant of the TREM2 gene.
  • However, the common TREM2 variant is linked to faster plaque growth at later stages.
  • TREM2 appears to modify the way immune cells respond to tau tangles.
  • Another mouse study found that overactive microglia (achieved by turning off another gene) were linked to both better removal of amyloid-beta, and loss of synapses. This may help explain why reducing amyloid plaques often fails to improve cognition.

Aging linked to impaired garbage collection in the brain

  • Study indicates APOE4 carriers are only at greater Alzheimer's risk if they have chronic inflammation.
  • Large study finds increasing inflammation linked to more white matter damage.
  • Common causes of chronic inflammation include cardiovascular disease, heart failure, diabetes, high blood pressure and infections.

Link found between chronic inflammation and Alzheimer's gene risk

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