Alzheimer's disease
Alzheimer's disease is a progressive neurodegenerative disorder that primarily affects memory, thinking, and behavior. It is the most common cause of dementia, a term used to describe a decline in cognitive function severe enough to interfere with daily life. The disease is characterized by the accumulation of abnormal proteins in the brain, specifically amyloid plaques and tau tangles, which lead to the death of brain cells (neurons) and the loss of connections between them.
General Symptoms of Alzheimer's Disease:
1. Memory Loss: One of the earliest and most common signs, especially forgetting recently learned information. People may repeatedly ask the same questions or rely increasingly on memory aids, like notes or reminders.
2. Difficulty with Problem Solving and Planning: Trouble managing finances, following a recipe, or keeping track of monthly bills due to reduced ability to develop or follow a plan.
3. Confusion with Time or Place: Losing track of dates, seasons, or the passage of time. Individuals may forget where they are or how they got there.
4. Challenges in Completing Familiar Tasks: Difficulty performing daily activities, such as driving to a familiar location, remembering the rules of a game, or managing tasks at work.
5. Trouble Understanding Visual Images and Spatial Relationships: People may have difficulty reading, judging distance, or determining color contrast, which can affect driving or walking.
6. Problems with Words in Speaking or Writing: Difficulty following or joining conversations. Individuals may stop in the middle of a conversation and not know how to continue or struggle to find the right word.
7. Misplacing Things and Losing the Ability to Retrace Steps: They may put things in unusual places and are unable to retrace their steps to find them. This can also lead to accusing others of stealing.
8. Decreased or Poor Judgment: Decline in judgment, particularly with decision-making. This might include making poor financial choices or neglecting personal hygiene.
9. Withdrawal from Work or Social Activities: As cognitive symptoms progress, individuals may begin to avoid social activities, hobbies, or work projects.
10. Changes in Mood and Personality: Individuals with Alzheimer's can become confused, suspicious, depressed, fearful, or anxious. They may easily become upset in unfamiliar settings.
Alzheimer's typically develops slowly, with symptoms worsening over time. While there is currently no cure for Alzheimer's, treatments exist to temporarily alleviate some symptoms, and ongoing research aims to find better management and potential prevention strategies.
what are the risk factors for developing Alzheimer's disease
Several risk factors are associated with the development of Alzheimer's disease, although the exact cause is still not fully understood. These risk factors can be grouped into modifiable and non-modifiable categories.
Non-Modifiable Risk Factors
1. Age:
Advancing age is the most significant risk factor. Most individuals with Alzheimer's are 65 or older, and the risk of developing the disease doubles every five years after age 65. However, Alzheimer's can also occur in people in their 40s or 50s, known as early-onset Alzheimer's.
2. Genetics/Family History:
Having a family history of Alzheimer's disease increases the likelihood of developing the condition. Specific genes, such as the APOE-e4gene, are known to increase the risk, especially for late-onset Alzheimer's.
Rarely, early-onset Alzheimer's can be caused by mutations in genes such as APP, PSEN1, or PSEN2. These are inherited and can lead to Alzheimer's developing before the age of 65.
3. Gender:
Women are more likely to develop Alzheimer's than men, though the reasons are not entirely clear. It may be related to women living longer, or hormonal differences, particularly related to estrogen.
4. Down Syndrome:
People with Down syndrome have a significantly higher risk of developing Alzheimer's disease, often in middle age, due to an extra copy of chromosome 21, which contains the gene responsible for producing amyloid precursor protein (APP).
Modifiable Risk Factors
1. Cardiovascular Health:
Conditions that affect the heart and blood vessels, such as high blood pressure (hypertension), high cholesterol, diabetes, and atherosclerosis, increase the risk of Alzheimer's. Damage to blood vessels in the brain due to poor cardiovascular health may contribute to cognitive decline.
2. Lifestyle and Habits:
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Physical inactivity: A sedentary lifestyle is associated with a higher risk of Alzheimer's. Regular physical activity can help maintain brain health.
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Diet: A poor diet, particularly one high in saturated fats and sugars, may increase the risk. Diets like the Mediterranean or DASH (Dietary Approaches to Stop Hypertension) diet, which are rich in fruits, vegetables, and healthy fats, may help protect against Alzheimer's.
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Smoking: Smoking damages the blood vessels and increases the risk of Alzheimer's and other forms of dementia.
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Excessive alcohol consumption: Heavy alcohol use has been linked to an increased risk of cognitive decline.
3. Cognitive Activity and Education:
Lower levels of educationand lack of cognitive engagementin midlife are associated with an increased risk. Keeping the brain active by engaging in mentally stimulating activities (such as reading, puzzles, or learning new skills) is thought to be protective.
4. Social Engagement:
Social isolationand a lack of meaningful relationships can increase the risk of cognitive decline. Staying socially active helps maintain cognitive health.
5. Head Trauma:
Traumatic brain injury (TBI), especially repeated injuries, may increase the likelihood of developing Alzheimer's. Wearing helmets during sports and seat belts in vehicles can reduce the risk of TBI.
6. Sleep Disorders:
Chronic sleep problems, especially sleep apnea and insomnia, have been linked to an increased risk of developing Alzheimer's. Poor sleep can lead to the buildup of amyloid plaques in the brain.
Emerging Risk Factors
1. Chronic Inflammation:
Long-term, chronic inflammation in the body, which can be caused by various conditions (such as infections, autoimmune diseases, or obesity), is increasingly being recognized as a potential contributor to Alzheimer's.
2. Mental Health Conditions:
Conditions such as depression, anxiety,and chronic stresshave been linked to a higher risk of Alzheimer's. Managing mental health through therapy, medication, and stress-reduction techniques may lower risk.
Summary
While some risk factors for Alzheimer's disease, such as age and genetics, cannot be changed, others can be managed through lifestyle modifications. Maintaining heart health, staying physically and mentally active, engaging in social interactions, and adopting a healthy diet can help reduce the risk. Additionally, managing conditions such as diabetes, high blood pressure, and sleep disorders may offer protective benefits.
Citations:
[1] https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors
[2] https://www.nia.nih.gov/health/alzheimers-causes-and-risk-factors/what-causes-alzheimers-disease
[3] https://www.jax.org/news-and-insights/2019/december/will-i-get-alzheimers
[4] https://stanfordhealthcare.org/medical-conditions/brain-and-nerves/dementia/risk-factors.html
[5] https://www.nia.nih.gov/health/alzheimers-causes-and-risk-factors/thinking-about-your-risk-alzheimers-disease-five
[6] https://www.alzheimers.org.uk/about-dementia/types-dementia/who-gets-alzheimers-disease
[7] https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/symptoms-causes/syc-20350447
[8] https://www.alzint.org/about/risk-factors-risk-reduction/
How can environmental factors increase the risk of developing Alzheimer’s disease
Environmental factors, although not the primary cause of Alzheimer's disease, are increasingly recognized as potential contributors to the risk of developing the condition. These factors can influence brain health over time, often through prolonged exposure or chronic impact. Below are some key environmental factors that may increase the risk of Alzheimer's disease:
1. Air Pollution
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Fine particulate matter (PM2.5): Long-term exposure to air pollution, particularly fine particulate matter (PM2.5) and nitrogen dioxide (NO2), has been linked to an increased risk of cognitive decline and Alzheimer's. Pollutants may cause inflammation in the brain, oxidative stress, and damage to the blood-brain barrier, which can contribute to the buildup of amyloid plaques and tau tangles.
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Traffic-related air pollution: Studies have shown that individuals living in areas with high levels of traffic pollution are more likely to experience cognitive decline as they age.
2. Heavy Metals and Toxins
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Lead: Long-term exposure to lead, particularly during early developmental stages, may have lasting impacts on cognitive health. Lead exposure has been associated with accelerated cognitive aging and neurodegeneration.
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Mercury: Mercury exposure, often through certain types of fish or industrial contamination, can affect the brain. Mercury may contribute to neurodegenerative changes, although its direct link to Alzheimer's is still under study.
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Aluminum: While the role of aluminum in Alzheimer's is controversial, some research suggests that exposure to high levels of aluminum (found in certain water supplies, cookware, and antiperspirants) may contribute to the development of the disease.
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Pesticides: Exposure to certain pesticides, particularly organophosphates, may increase the risk of neurodegenerative diseases, including Alzheimer's. Pesticides can induce oxidative stress and damage neural pathways, contributing to cognitive decline.
3. Chronic Exposure to Solvents and Chemicals
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Industrial chemicals: Prolonged exposure to chemicals like solvents(used in paints, degreasers, and cleaning products), as well as polychlorinated biphenyls (PCBs)(used in manufacturing), has been linked to an increased risk of dementia. These chemicals may lead to oxidative stress and inflammation in the brain, promoting neurodegeneration.
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Agricultural exposure: Workers exposed to herbicides, fungicides,and pesticidesin agricultural settings may have a higher risk of developing Alzheimer's. These chemicals may disrupt normal brain function over time.
4. Occupational Exposure
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Construction and manufacturing: Certain professions, particularly those involving exposure to toxins like asbestos, heavy metals, and other industrial chemicals, may increase the risk of Alzheimer's due to prolonged inhalation or contact with harmful substances.
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Veterans: Veterans who have experienced combat, especially those exposed to explosions, burn pits, or chemical agents, may have a higher likelihood of developing cognitive impairments that could lead to Alzheimer's later in life.
5. Traumatic Brain Injury (TBI)
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Individuals who have experienced repeated head injuries(such as athletes in contact sports or those in high-risk occupations) are at an increased risk of developing Alzheimer's disease. TBI can damage brain cells, promote inflammation, and increase the buildup of amyloid plaques, leading to cognitive decline.
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Chronic Traumatic Encephalopathy (CTE), a condition often seen in athletes who experience repeated head trauma, has been linked to neurodegenerative diseases, including Alzheimer's.
6. Epidemiological Studies
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Several population-based studies have investigated the link between pesticide exposure and Alzheimer's risk:
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Farmers and agricultural workers, who are frequently exposed to pesticides, have been shown to have higher rates of cognitive impairment and Alzheimer's disease compared to the general population.
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A study published in JAMA Neurologyfound that individuals with higher levels of DDE(a breakdown product of DDT) in their blood were more likely to have Alzheimer's disease. This suggests a direct relationship between exposure to organochlorine pesticides and the risk of developing Alzheimer's.
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Another study in France, known as the PAQUID Study, showed that individuals exposed to pesticides in their occupations were more likely to experience cognitive decline and develop dementia, including Alzheimer's disease.
7. Occupational Exposure
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People working in agriculture, landscaping, or pest control are at higher risk due to frequent, prolonged contact with pesticides. The risk increases with the duration and intensity of exposure. These individuals may inhale pesticides or absorb them through the skin, which can lead to higher levels of toxins in their system over time.
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The cumulative effect of low-dose exposure over many years is thought to be particularly harmful, as it can lead to a slow buildup of neurotoxic substances in the brain.
8. Genetic Susceptibility
Some individuals may be genetically predisposed to be more sensitive to the effects of pesticide exposure. For example, people carrying the APOE-e4allele, which is associated with a higher risk of Alzheimer's, may be more vulnerable to the neurotoxic effects of pesticides.
9. Prevention and Regulation
In response to growing evidence of the harmful effects of certain pesticides, many countries have implemented regulations to limit or ban the use of particularly dangerous chemicals, such as DDT.
However, pesticide residuein food, water, and the environment still poses a potential risk to the general population. Reducing exposure to pesticides by:
- Choosing organic produce.
- Washing fruits and vegetables thoroughly.
- Avoiding pesticide use in homes or gardens.
- Wearing protective gear when working with pesticides.
10. Long-Term Impact
While the direct causality between pesticides and Alzheimer's disease continues to be studied, the evidence suggests that long-term pesticide exposure, particularly to organophosphates and organochlorines, is linked to a higher risk of cognitive decline and the development of Alzheimer's disease. Public health initiatives aimed at reducing pesticide exposure may help mitigate this risk.
Conclusion
Chronic exposure to pesticides, particularly organophosphates and organochlorines like DDT, has been associated with an increased risk of Alzheimer's disease. Pesticides can induce oxidative stress, neuroinflammation, and disruption of neurotransmitter systems, all of which are key factors in the development of Alzheimer's. Occupational exposure, especially for agricultural workers, poses a significant risk, and efforts to reduce pesticide exposure through regulation, protective measures, and lifestyle choices may help lower the risk of neurodegenerative diseases like Alzheimer's.
Citations:
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5007474/
[2] https://www.nature.com/articles/nrneurol.2010.80
[3] https://ehjournal.biomedcentral.com/articles/10.1186/s12940-019-0494-2
[5] https://www.wjgnet.com/2307-8960/full/v11/i24/5628.htm
[6] https://link.springer.com/article/10.1007/s11356-020-08243-z
[7] https://bmcgeriatr.biomedcentral.com/articles/10.1186/s12877-016-0342-y
Pesticides and Alzheimer’s disease
Pesticides have been increasingly studied as potential environmental risk factors for Alzheimer's disease.
Chronic exposure to certain types of pesticides, especially in agricultural or industrial settings, can have neurotoxic effects that may contribute to the development of Alzheimer's and other neurodegenerative diseases. Here's a closer look at the relationship between pesticides and Alzheimer's disease:
1. Neurotoxic Effects of Pesticides
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Pesticides, particularly organophosphates, organochlorines, and carbamates, are known to have neurotoxic properties. These chemicals can interfere with normal brain function by:
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Disrupting neurotransmitter systems (especially acetylcholine, which is critical for memory and learning).
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Inducing oxidative stress, which leads to the production of free radicals that damage brain cells.
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Triggering inflammation in the brain, a key contributor to neurodegenerative diseases.
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Promoting the buildup of beta-amyloid plaquesand tau tangles, which are hallmark features of Alzheimer's disease.
2. Organophosphate Pesticides
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Organophosphates, commonly used in agricultural and household settings, inhibit the enzyme acetylcholinesterase, which breaks down the neurotransmitter acetylcholine. This leads to an accumulation of acetylcholine, disrupting communication between neurons and potentially causing long-term brain damage.
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Research has shown that chronic exposure to organophosphates is linked to cognitive decline and an increased risk of Alzheimer's, especially for individuals with prolonged exposure, such as farmers or agricultural workers.
3. Organochlorine Pesticides
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Organochlorines, including chemicals like DDT(dichlorodiphenyltrichloroethane), were widely used in the past and persist in the environment due to their slow degradation. Although banned in many countries, organochlorines remain present in some areas and can accumulate in the body over time.
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Studies have found higher levels of DDT and its metabolite DDE(dichlorodiphenyldichloroethylene) in the brains of individuals diagnosed with Alzheimer's disease. The presence of these chemicals has been linked to increased beta-amyloid production, which contributes to the progression of Alzheimer's.
4. Carbamates
Carbamatesare another class of pesticides that, like organophosphates, inhibit acetylcholinesterase. Chronic exposure to these chemicals has been linked to memory problems, reduced cognitive function, and an increased risk of Alzheimer's.
5. Increased Inflammation and Oxidative Stress
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Many pesticides are associated with increased levels of oxidative stressand chronic inflammationin the brain. Oxidative stress refers to an imbalance between the production of free radicals and the body's ability to counteract their harmful effects. Chronic inflammation and oxidative damage are known contributors to Alzheimer's disease.
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Pesticides may also disrupt the blood-brain barrier, a protective barrier that prevents harmful substances from entering the brain. Once the blood-brain barrier is compromised, toxins and other harmful compounds can more easily damage brain cells.
6. Lifestyle and Diet Influenced by the Environment
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Urban living: Individuals living in urban environments may have limited access to green spaces, fresh food, and clean air, leading to a higher risk of poor lifestyle choices, such as sedentary behavior, poor diet, and social isolation, all of which increase Alzheimer's risk.
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Food contaminants: Exposure to food additives, preservatives, and contaminants such as pesticidesand heavy metalsin water or food supplies can increase the risk of Alzheimer's by contributing to oxidative stress and inflammation in the brain.
7. Radiation Exposure
Radiation therapy or environmental radiation: Although not a major risk factor for most individuals, those exposed to high levels of radiation (from treatments like radiation therapy or environmental exposure) may experience damage to brain cells, increasing the risk of cognitive impairment and Alzheimer's.
8. Socioeconomic and Psychosocial Factors
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Low socioeconomic status: People from lower socioeconomic backgrounds may experience more environmental stressors, limited access to healthcare, poor nutrition, and more exposure to environmental pollutants, all of which can increase Alzheimer's risk.
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Psychosocial stress: Environmental stressors, including chronic exposure to stressful environments, can lead to prolonged stress, which is associated with changes in brain structure, neuroinflammation, and an increased risk of Alzheimer's.
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Urban noise pollution: Constant exposure to high levels of noise, particularly in densely populated urban areas, may increase stress and sleep disturbances, both of which have been linked to cognitive decline.
9. Sleep Disturbances
Environmental factors affecting sleep: Living in environments with excessive noise, light pollution, or other disturbances may lead to chronic sleep problems. Sleep is essential for clearing amyloid-beta proteins from the brain, and chronic sleep deprivation has been linked to an increased risk of Alzheimer's.
10. Infections
Viral and bacterial infections: There is ongoing research into whether certain infections, like herpes simplex virus type 1 (HSV-1), may play a role in the development of Alzheimer's. Chronic infections may trigger inflammatory responses in the brain that promote amyloid plaque accumulation.
Conclusion
Environmental factors, such as exposure to air pollution, toxins, heavy metals, and certain chemicals, as well as traumatic brain injuries and chronic stress, may increase the risk of Alzheimer's disease. While these factors do not cause Alzheimer's directly, they may contribute to brain changes that increase vulnerability to cognitive decline. Reducing exposure to harmful environmental agents, improving air quality, and addressing occupational hazards may help lower the risk of Alzheimer's disease.
Citations:
[1] https://link.springer.com/article/10.1007/s11356-020-08243-z
[2] https://bmcgeriatr.biomedcentral.com/articles/10.1186/s12877-016-0342-y
[3] https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2022.1042488/full
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5059894/
[5] https://today.usc.edu/alzheimers-environmental-risk-factors-usc-research/
[6] https://www.mayoclinic.org/diseases-conditions/alzheimers-disease/symptoms-causes/syc-20350447
[8] https://www.nia.nih.gov/health/alzheimers-causes-and-risk-factors/what-causes-alzheimers-disease
What are the most common pesticides linked to Alzheimer's disease
Based on the search results, several types of pesticides have been linked to an increased risk of Alzheimer's disease (AD):
Organochlorines
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DDT and its metabolite DDE have been associated with increased AD risk in multiple studies[1][3].
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Elevated concentrations of organochlorine pesticides were linked to cognitive decline[1].
Organophosphates
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Occupational exposure to organophosphates was shown to significantly increase the risk of developing AD later in life[3].
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Organophosphates are known to affect central nervous system functioning as acetylcholinesterase inhibitors[3].
Other Pesticide Classes
Carbamates, pyrethroids, and neonicotinoids have also been associated with tau hyperphosphorylation and neuroinflammation, which are linked to AD pathology[4].
Specific Pesticides
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Paraquat has been implicated in some studies as potentially increasing AD risk[2].
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Glyphosate was found to cross the blood-brain barrier in studies, potentially increasing risk of neurological diseases like AD[1].
General Pesticide Exposure
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Multiple meta-analyses and systematic reviews have found a positive association between overall pesticide exposure and increased risk of AD[2][3].
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Living near chemical-intensive agricultural environments has been linked to heightened AD risk[1].
While the evidence suggests associations between various pesticides and AD risk, more research is still needed to establish definitive causal relationships for specific pesticides. The mechanisms may involve oxidative stress, mitochondrial dysfunction, neuroinflammation, and alterations in tau protein phosphorylation.
Citations:
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5007474/
[3] https://www.nature.com/articles/nrneurol.2010.80
[4] https://www.wjgnet.com/2307-8960/full/v11/i24/5628.htm
[5] https://ehjournal.biomedcentral.com/articles/10.1186/s12940-019-0494-2
[6] https://www.center4research.org/pesticides-alzheimers-disease/
[8] https://link.springer.com/article/10.1007/s11356-020-08243-z