Ageing Flashcards
How does the allostatic load contribute to ageing?
- Social, psychological, lifestyle and nutritional factors all interact with our genome to create resilliance to ageing or accelerated deterioration
- Exposure to toxins (environment, household, cosmetics), inadequate exercise, poor nutrition, high stress, genetic susceptibility, chronic inflammation and dysbiosis all play a role at a physiological and molecular level.
How can mitochondrial dysfunction lead to chronic diseases?
Mitochondria are the main source of ROS in a cell.
* Oxidative stress within mitochondria leads to mtDNA mutations, reduced ATP and energy.
* Mitochondrial dysfunction leads to apoptosis, linked to MS, Alzheimer’s and Parkinson’s diseases and many chronic inflammatory diseases.
What is inflammageing and what is it a result of?
- Chronic low-grade inflammation that increases as we age , leading to many age-related diseases.
- Inflammageing is the result of pathological stimulation of the innate immune system.
- Pathogens, damaged tissues, altered gut microbiota, antibiotics, steroids, and antihistamines all promote chronic inflammation.
What is hormesis and what are some things that induce it? Why does it extend life and health span?
“A process in which exposure to a low level of stress or toxicity induces an adaptive beneficial effect in a cell or organism”.
eg Calorie restriction, phytochemicals, exercise, cognitive stimulation, intermittent cold and heat mildly stress the body
They can all extend lifespan and healthspan because healthy body responds to mild stress by increasing the production of endogenous antioxidants (glutathione, catalase, superoxide dismutase and phase II detoxification enzymes) cellular quality control mechanisms.
How is NrF2 implicated in hormesis?
Nrf2 is a transcription factor which senses cellular stress and then responds by attaching to the antioxidant response element (ARE) within DNA and upregulating the expression of glutathione enzymes, superoxide dismutase, catalase and phase II detoxification enzymes.
This increases the production of endogenous antioxidants
How is calorie restriction and exercise anti-ageing?
Calorie restriction and exercise
induce stress partly by depleting cellular energy ATP ADP NADH NAD.
This activates AMPK, a pro-longevity protein.
and the sirtuins (SIRT 1-7), a family of anti-ageing proteins.
AMPK and sirtuins initiate numerous processes that improve health and prolong life including autophagy (self-eating)
where worn-out or damaged cellular components are digested to improve the quality of the whole organism.
Exercise increases levels of PGC1-alpha, a protein that enables the synthesis of brand new mitochondria
Why is mitophagy important in a healthy cell?
- In a healthy cell, mitochondria undergo mitophagy every 9-25 days after biogenesis as part of quality control to maintain their ability to produce energy
- Liver mitochondria are turned over more rapidly than heart, kidney and brain mitochondria due to toxicity
What are the 9 key signatures of ageing?
Genome instability.
* Telomere shortening.
* Epigenetic alterations.
* Loss of protein regulation and disposal — a
hallmark of Alzheimer’s and Parkinson’s diseases.
* Insulin resistance and poor nutrient sensing.
* Cell senescence (biological ageing).
* Stem cell loss.
* Altered intercellular communication.
Why is social connection important? who is it most important for?
- Social connection is most important for children and the elderly.
- Poor childhood social connection predisposes a person to inflammatory diseases in later life.
- In the elderly, social connection is a powerful anti-inflammatory — as strong as smoking cessation or exercise!
- BMI, blood pressure and inflammation can all be reduced by good social connections — social stress has the opposite effect
Why is excess phase 1 detoxification linked to ageing and cancer? What can slow down this process?
- Phase I detoxification enzymes transform xenobiotics, steroid hormones and drugs into reactive intermediates by the addition of oxygen, more toxic than they were to start with
- Hydrocarbons are common xenobiotics which induce phase I detoxification enzymes.
- Cells detect many xenobiotics via the aryl hydrocarbon receptor AhR which binds to the DNA xenobiotic response element (XRE) to drive gene expression of phase I enzymes.
- Over-activation of the aryl hydrocarbon receptor (AhR) leads to accelerated ageing, cardiovascular disease and cancer.
- Green tea, turmeric, quercetin and resveratrol desensitise the AhR, slow down phase I and protect against cancer.
How does calorie restriction help with healthy ageing? how can a ketogenic diet help?
- Activate sirtuins, anti-ageing proteins which improve insulin sensitivity, mitochondrial activity, cardiovascular health, fat metabolism, DNA integrity and also lower inflammation.
- Promote autophagy to aid cellular rejuvenation.
- Increase adiponectin, an adipokine associated
with longevity. - Ketogenic diets may mimic some of the health benefits
of fasting by shifting metabolism toward beta-oxidation
and ketone synthesis.
Also activates AMPK which initiates numerous processes that improve health and prolong life including autophagy (self-eating)
How does obesity and insulin resistance increase accelerated ageing?
Leads to:
* Mitochondrial dysfunction and reduced biogenesis, hindering tissue repair and renewal.
* Increased inflammaging.
- Proteins modified by glycation are able to bind to AGE receptors (RAGEs) and promote inflammation, strongly associated with accelerated ageing,
neurodegeneration, diabetes and cancer.
What is dementia and what is the most common one?
Dementia describes a syndrome of cognitive impairment that affects memory recall, cognitive abilities and behaviour, and significantly interferes with a person’s ability to perform daily activities.
* Alzheimer’s disease (AD) is the most common form of dementia and accounts for 60–80% of all dementia cases.
Name some dementia risk factors
Chronic / acute stress.
* Proton pump inhibitor medication.
* Poor diet (junk food, sugars).
* Vitamin and nutritional deficiencies,
e.g., vitamin A, D, C, B6, B9, B12 etc.
* Poor lifestyle (e.g., smoking and
drinking alcohol)
* Vaccinations.
* Hypertension and diabetes.
* Mental inactivity.
* Obesity.
* Physical inactivity.
* Social isolation.
* Environmental toxins.
* ApoE4 polymorphism.
* Mid-life depression.
What are the four main types of dementia?
1) Frontotemporal dementia: Behavioural, language and movement difficulties, driven by atrophy of frontal and temporal lobes.
2) Vascular dementia: Impaired blood flow to the brain leading to cognitive decline. Often associated with cardiovascular disease.
3) Lewy body dementia: Lewy bodies are abnormal clumps of protein that cause alterations in thoughts, perceptions and movement. Lewy bodies are also found in Parkinson’s disease patients.
4) Alzheimer’s disease: Amyloid beta and tau are two proteins which correlate with Alzheimer’s disease. Patients suffer progressive loss of memory, language and reasoning.
How are a build up of amyloid beta and tau proteins implicated in AD?
- Amyloid plaques and misfolded tau proteins are characteristic of AD, They are symptoms and not the cause!
- Infection, inflammation and oxidative stress drive amyloid production.
- Amyloid beta is now thought to be the brain’s protective response to a threat rather than the cause of Alzheimer’s disease.
What are Dr Bredesens 3 catagories of AD?
- Inflammation or ‘hot’: Associated with increased innate immune system activation, inflammation, pro-inflammatory microglia (M1) and reduced sirtuin (SIRT1) activity compared to NF kappa B.
- Atrophic or ‘cold’: Loss of trophic support from neurotrophins such as brain-derived neurotrophic factor (BDNF).
- Cortical or ‘toxic’: associated with environmental toxins, leading to chronic inflammation and general brain atrophy.
What are microglia, how can they shift including transcription factors and why is this protective?
Microglia are the resident immune cells of the brain:
*M1 are the proinflammatory type, but can be polarised to an M2 (anti-inflammatory) type. This shift is supported by transcription factor NrF2, which can be protective in Alzheimer’s disease.
- The inflammatory transcription factor NF Kappa B promotes the neuroinflammatory M1 phenotype.
How are TLR’s implicated in microglial- related inflammation? What can suppress this inflammatioon?
- Dysbiosis of gut microbiota and pathogens leads to pro-inflammatory communication to TLRs on brain microglia via the microbiota-gut-brain axis. Oral dysbiosis: P. gingivalis
is associated with a significantly ↑ Alzheimer’s risk. - TLRs on brain microglia are sensitive to our own damaged tissue, leading to a spiral of inflammation and neuronal loss.
- Oxytocin, produced during enriched social interactions, can act through the Vagus nerve to suppress microglia-related inflammation.
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