4.1. Describe causes of age associated diseases

This guide will help you answer 4.1. Describe causes of age associated diseases.

As people age, their bodies go through changes that can affect how well their organs and systems work. These changes increase the likelihood of developing age-associated diseases. These conditions are diseases that are more common in older adults and result from a combination of genetic, environmental, lifestyle, and biological factors. This guide will look at some of the causes behind these diseases and their contributors.

Biological Ageing

Biological ageing refers to the natural wear and tear of body systems over time. This process can be affected by oxidative stress, which is when harmful substances called free radicals damage the cells. Free radicals are molecules produced by chemical reactions in the body, such as during metabolism (how the body processes food for energy). Over time, the damage done by free radicals builds up and can impair the normal functioning of organs.

Another important biological cause is cellular senescence. Cellular senescence occurs when cells stop dividing and die, causing a decrease in cell renewal. This leads to age-related problems, such as weaker tissues that struggle to repair themselves. For example, in older individuals, bone cells may not replace themselves as quickly, contributing to conditions like osteoporosis (weakened bones).

Inflammation, often referred to as “chronic inflammation,” also plays a major role. As individuals age, their immune systems become less effective. This is called immunosenescence. The body may also stay in a state of low-grade inflammation, known as “inflammaging,” which can lead to diseases such as arthritis or cardiovascular disease.

Genetics

Genes can influence how people age and their likelihood of developing specific diseases. Some people inherit mutations—changes in their DNA—that make them more prone to certain conditions. For example:

• Alzheimer’s disease: Certain genetic combinations, like the APOE4 allele, can increase the risk of developing this neurodegenerative disease, which causes memory loss and cognitive decline.
• Cancer: Aging increases the chance of genetic mutations in cells. Over decades, damaged DNA can accumulate, leading to uncontrolled cell division and tumour growth.

Although genetics plays a role, lifestyle and environmental factors can trigger or worsen the effects of these inherited tendencies.

Cardiovascular System Changes

The heart and blood vessels experience physical changes as part of ageing. Blood vessels lose some of their elasticity, which forces the heart to work harder to pump blood effectively. This can raise blood pressure, leading to hypertension (high blood pressure). Hypertension, in turn, increases an individual’s risk of stroke, heart attack, and kidney damage.

A build-up of fatty deposits, known as plaques, can occur inside arteries. This process is called atherosclerosis. Reduced blood flow caused by narrowed arteries can increase the risk of coronary artery disease, heart attacks, and peripheral vascular disease (reduced blood flow to limbs).

Diabetes and high cholesterol are additional causes that damage blood vessels over time, contributing to these conditions.

Weakened Musculoskeletal System

The musculoskeletal system—the body’s framework of bones, muscles, and joints—weakens with age. Several factors affect this process:

• Osteoporosis: Low bone density or fragile bones can develop because bones lose calcium and other minerals. Older adults may absorb nutrients less efficiently from their diet, which can contribute to the loss of bone strength.
• Sarcopenia: The natural loss of muscle mass as people grow older makes individuals weaker and more frail. Reduced physical activity, hormonal changes, and poor nutrition are leading causes.
• Osteoarthritis: This is a wear-and-tear condition where the cartilage (the cushion between bones in joints) degenerates. This causes pain, stiffness, and swelling in commonly used joints, such as knees, hips, and hands.

These changes result in mobility issues, reduced physical strength, and an increased risk of falls or fractures.

Neurological Changes

As people age, their brain and nervous system can decline in function. These changes are commonly linked to neurodegeneration, where nerve cells (neurons) are progressively damaged or lost. Causes of age-related neurological diseases include:

• Alzheimer’s and dementia: These conditions result from abnormal changes in brain proteins, such as amyloid plaques and tau tangles, which lead to brain cell death.
• Parkinson’s disease: Due to the loss of dopamine-producing neurons in the brain, movement becomes impaired, leading to symptoms like tremors and stiffness.
• Stroke: Blood clotting or ruptured blood vessels in the brain can reduce blood supply, causing brain cell damage. Stroke is often linked to cardiovascular problems, like high blood pressure or atherosclerosis.

These conditions heavily impair cognitive abilities, memory, mood, and physical coordination—greatly impacting daily life for older individuals.

Changes in the Endocrine System

The endocrine system produces hormones that regulate key bodily functions. Hormones decline naturally with age, leading to a variety of health conditions, such as:

• Diabetes: Insulin resistance develops when the body becomes less effective at processing glucose (sugar), leading to type 2 diabetes. This risk increases with obesity and inactivity.
• Thyroid disorders: Problems with the thyroid gland, like hypothyroidism (underactive thyroid), become more common, affecting metabolism, energy levels, and weight regulation.
• Menopause and andropause: Hormonal shifts during middle age, such as reduced production of oestrogen in women or testosterone in men, can lead to osteoporosis, heart disease, and sexual health concerns.

Digestive System Function

Ageing can affect the digestive system by slowing down processes and reducing its overall efficiency. Common causes of age-related digestive problems include:

• Weakened muscles: Reduced muscle tone in the digestive tract can cause constipation by slowing the movement of food and waste.
• Nutritional deficiencies: The stomach may produce less acid, which affects the absorption of nutrients like vitamin B12, iron, and calcium.
• Gastrointestinal diseases: Older adults may be at higher risk of conditions like diverticulosis (formation of pouches in the intestinal wall), ulcers, and gastroesophageal reflux disease (GERD).
• Medications and lifestyle: Many older adults take prescription drugs that may have gastrointestinal side effects.

Immune System Decline

The immune system weakens as individuals grow older, leaving the body more vulnerable to infections, cancer, and autoimmune diseases. This decline in immunity is often called immunosenescence. Some of the factors contributing to this are:

• The reduced production of immune cells, such as white blood cells.
• Delays in the immune system recognising and fighting infections.
• Poor response to vaccines, which makes infections like flu or pneumonia more dangerous for the elderly.

Cancer risk also rises with age because the immune system becomes less effective at destroying abnormal or mutated cells.

Respiratory System

The respiratory system shows signs of ageing as lung tissue becomes less elastic, and chest wall muscles become weaker. This may make breathing slightly more difficult over time. Diseases associated with this include:

• Chronic obstructive pulmonary disease (COPD): Linked to smoking or exposure to pollutants, older adults with damaged airways often develop COPD.
• Pneumonia: A weakened immune system makes older people more prone to severe chest infections.
• Asthma: Some individuals may develop adult-onset asthma linked to chronic inflammation of airways.

Skin, Vision, and Hearing Changes

Age-related damage can affect skin, vision, and hearing. Changes in these areas might seem minor compared to internal diseases but can cause discomfort or impair wellbeing.

• Skin: Over time, the skin loses collagen (a protein giving skin its elasticity) and becomes thinner. This leads to dryness, wrinkles, and a higher risk of pressure sores or skin infections.
• Eyes: Conditions like cataracts (clouding of the eye lens), macular degeneration (loss of central vision), and glaucoma (increased eye pressure damaging the optic nerve) are common.
• Hearing: Damage to small sensory cells in the inner ear from long-term noise exposure or ageing results in hearing loss, known as presbycusis.

Lifestyle Risk Factors

Although biological ageing contributes to diseases, choices people make during their life also play a role. Common contributing factors include:

• Poor diet: High-fat, high-sugar diets lead to obesity, high cholesterol, and insulin resistance.
• Smoking: Damages lung tissues, accelerates cardiovascular disease, and increases cancer risk.
• Alcohol consumption: Overconsumption puts a strain on the liver, brain, and other organs.
• Lack of exercise: Physical inactivity reduces cardiovascular health, bone density, and muscle mass.
• Stress and mental health: Chronic stress significantly contributes to high blood pressure, poor sleep, and immune suppression.

Environmental Factors

Exposure to toxins and pollutants can cause age-related illnesses. Aerosol sprays, industrial waste, or ultraviolet (UV) radiation can increase inflammation, promote DNA damage, and raise cancer risks. For example, long-term UV exposure may result in skin cancers or damage connective tissues that repair the skin barrier.

Reducing Age-Related Disease Risks

While you cannot eliminate the effects of ageing, certain steps can reduce the risk of diseases:

• Eating a balanced diet rich in fruits, vegetables, and lean proteins.
• Regular exercise to maintain healthy bones, muscles, and cardiovascular fitness.
• Avoiding smoking and excessive alcohol intake.
• Staying mentally and socially active to protect brain function.
• Attending regular check-ups to detect health issues early.

Understanding the causes of age-associated diseases is key to preventing them wherever possible. Building a healthier lifestyle earlier in life can significantly lower risks as you grow older.