Posts Tagged ‘healthy lifestyle’

Alzheimer’s Disease (AD)

September 24, 2019

This post is based on an important book by Scott D. Slotnick titled “Cognitive Neuroscience of Memory.” Remember to consult the website http://www.brainfacts.org/
to see the anatomical information referred to in this post.

As AD progresses from earlier to later stages, atrophy starts in the medial temporal lobe, extends to the parietal lobe, and finally includes the frontal lobe. The long-term memory impairment in early AD patients can be attributed to the disrupted processing in the hippocampus and parietal cortex, to regions that have been associated with this cognitive process. As the disease progresses, other cognitive processes are disrupted such as attention and language, which both depend on the dorsolateral prefrontal cortex.

In early AD patients, as atrophy begins in the parietal cortex and the frontal cortex, there have also been reports of increases in fMRI activity within cortical regions. It is unknown whether these increases in cortical fMRI activity reflect a compensatory mechanism, which is often assumed to be the case, or reflect non-compensatory hyperactivity due to neural disruption.

In addition to brain atrophy, AD patients have abnormal high levels of proteins in different brain regions. In the medial temporal lobe, the accumulation of tau protein leads to neurofibrillary tangles. In cortical regions, such as the parietal cortex in early AD, the accumulation of amyloid-B protein leads to amyloid plaques. The neurofibrillary tangles in the medial temporal lobe and amyloid plaques in cortical regions can be assumed to disrupt neural processing in these regions.

Dr. Slotnick writes, “There is an influential hypothesis that there is a causal relationship between default network activity that leads to deposition of amyloid that results in atrophy and disrupted metabolic activity, which impairs long-term memory in AD patients. The regions in the default network are active when participants are not engaged in a task and include the dorsolateral prefrontal cortex, the medial prefrontal cortex, the inferior prefrontal cortex and the medial parietal cortex. In AD patients, amyloid deposition occurs in the same regions, which suggest the default network activity may lead to amyloid deposition. Dr. Slotnick suggests that perhaps higher level of amyloid deposition, which occurs in late AD patients, is necessary to produce atrophy in the frontal cortex.

Healthy memory readers should recognize the similarity between the default network and Kahneman’s System 1 processing. System 1 processing is the default network that needs to be disrupted to engage in System 2 processing, better known as thinking.

Dr. Slotnick continues, “If high amyloid deposition is a causal factor in developing AD, older adults with low levels of amyloid should be at decreased risk for developing this disease. There is some evidence that cognitive engagement and exercise throughout life may reduce the amyloid level in the brains of healthy older adults as a function of cognitive engagement (System 2 processing), and this was compared to the cortical amyloid levels . Participants rated the frequency which they engaged in cognitively demanding tasks such as reading, writing, going to the library, or playing games at five different ages (6, 12, 18, 40, and their current age). Healthy older adults with greater cognitive engagement throughout their lifetime, as measured by the average cognitive activity at the five ages, had lower levels of amyloid in default network regions. Moreover, the healthy older adults in the lowest one-third of lifetime engagement had amyloid levels that were equivalent to AD patients, and the healthy older adults in the highest one-third of lifetime cognitive engagement had amyloid levels that were equivalent to young adults.

It should also be noted that many have died who upon autopsy had levels of amyloid plaque and neurofibrillary tangles definitive of AD, but who never exhibited any of the behavioral or cognitive symptoms characteristics of the disease. The explanation typically offered for these individuals is that they had built a cognitive reserve as a result of the mental activities they had engaged in during their lifetimes.

There is a wide variety of products sold to prevent AD, such as computer games and pills that increase short-term memory. But it should be clear from the posts on cognitive science that the entire brain is involved. That is why the healthy memory blog strongly recommends growth mindsets with continual learning throughout the lifespan. These make heavy use of System 2 processing. Of course, a healthy lifestyle that includes physical exercise must also be part of the mix.

Nice Prize for Alzheimer’s Work

April 5, 2018

The title of this post is identical to the first half of a title of an article by Jacqui Wise in the news section of the 17 March 2018 issue of the New Scientist. The second half if the title is “shame about the lack of a cure.” The following is directly from the article, “In giving the 1 million Euro prize to four researchers in the UK, Germany, and Belgium, Denmark’s Lundbeck Foundation is likely to rekindle hopes of a cure being within reach. However, translating the work—much of it in animals—into drugs remains as frustratingly out of reach as ever.”

There was a healthy memory post on August 20, 2011 titled “The Myth of Alzheimer’s.” That post was on a book by Peter J. Whitehouse, M.D., Ph.D., and Daniel George, M.Sc.. Dr. Whitehouse had been conducting research on destroying or preventing the amyloid plaques and neurofibrillary tangles that are the defining characteristics of the disease. His research was quite profitable and would have been continuing today, had he not come to the firm conclusion that this research would never pay off. He switched to conducting research on humans suffering from the disease.

The following is taken from that 20 August 2011 healthy memory blog post:
“The thesis of the book is best captured from the following excerpt from page 220, …”It is unlikely that there will ever be a panacea for brain aging and baby boomers should not rely on extraordinary advancements being made in their lifetimes besides the promises of the Alzheimer’s disease empire that make their way into our headlines. Our attention must begin shifting from mythical cure to hard-earned prevention, from expecting a symptomatic treatment for Alzheimer’s disease to choosing behaviors that may delay the effects “of cognitive decline over the course of our lives.” Many, if not most, of the behaviors he discusses have been mentioned and advocated in the Healthymemory Blog.

The book provides a superb tutorial on the history of Alzheimer’s disease from its unassuming beginnings to the development of an Alzheimer’s disease empire. It reviews the science underlying Alzheimer’s disease and the role of genetics in Alzheimer’s disease. It discusses past and present treatments for Alzheimer’s disease. It explains how to identify someone who might need a prescription for memory loss, and how to prepare for a doctor’s visit. It presents a new model for living with brain aging as well as a prescription for successful aging across the life span. An epilogue is titled ‘Thinking Like a Mountain: The Future of Aging.’”

The key behavior for minimizing the risk of suffering the symptoms of Alzheimer’s is living a healthy lifestyle that includes cognitive activity, that builds a cognitive reserve. This blog has many posts on both how to have a growth mindset and the benefits of a healthy mindset. Many people have died with amyloid plaque and neurofibrillary tangles, the defining characteristics of Alzheimer’s. Yet these people never knew they had Alzheimer’s as they exhibited none of the behavioral and cognitive symptoms. The reason given for these individuals is that they had a cognitive reserve. Recent research is finding evidence of how the brain changes as the result of cognitive reserve.

HM has a further conjecture that it is a specific type of processing that is beneficial. This is Kahnemans’s Type 2 processing, commonly referred to as thinking. Type 1 processing, our normal mode, called intuition, occurs quickly and with little attentional demands. As we age we tend to slip into more and more Type 1 processing. Entering “Kahneman” into the search block of the healthy memory blog will yield many posts on Kahneman and his Two Process Theory of cognition.

© Douglas Griffith and healthymemory.wordpress.com, 2018. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and
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