Common Chronic Diseases

Why This Matters

Chronic diseases aren't just isolated health problems—they're interconnected conditions that share common risk factors, biological mechanisms, and prevention strategies. You're being tested on understanding how lifestyle factors, genetics, and environmental exposures contribute to disease development, and why certain conditions cluster together in the same individuals. The connections between obesity, hypertension, diabetes, and heart disease, for example, demonstrate the concept of metabolic syndrome and the cascading effects of inflammation throughout the body.

Don't just memorize a list of symptoms and treatments. Know what modifiable vs. non-modifiable risk factors each disease involves, understand the difference between primary prevention (stopping disease before it starts) and secondary prevention (early detection and management), and recognize how health behaviors create ripple effects across multiple body systems. When you can explain why smoking damages both lungs and blood vessels, or how chronic inflammation links arthritis to heart disease, you're thinking like a health professional—and that's exactly what exam questions will demand.

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Cardiovascular and Circulatory Conditions

These conditions share a common thread: damage to blood vessels and disrupted blood flow. Atherosclerosis—the buildup of plaque in arterial walls—underlies most cardiovascular disease and creates the conditions for heart attacks and strokes.

Heart Disease

• Leading cause of death globally—responsible for approximately 1 in 4 deaths, making it the most significant chronic disease burden worldwide
• Modifiable risk factors include hypertension, high cholesterol, smoking, diabetes, and physical inactivity—meaning most cases are preventable
• Prevention focuses on lifestyle modification—heart-healthy diet, 150+ minutes weekly exercise, tobacco cessation, and stress management

Hypertension (High Blood Pressure)

• Called the "silent killer"—typically produces no symptoms until serious damage occurs to heart, brain, or kidneys
• Blood pressure classification uses systolic/diastolic readings; normal is below 120/80 mmHg, while hypertension begins at 130/80 mmHg
• Primary prevention strategy for multiple diseases—controlling blood pressure reduces risk of heart disease, stroke, and kidney failure simultaneously

Stroke

• Brain attack caused by interrupted blood flow—either from a clot (ischemic, 87% of cases) or bleeding (hemorrhagic)
• Time-critical emergency where "time is brain"—every minute without treatment destroys approximately 1.9 million neurons
• FAST recognition saves lives—Face drooping, Arm weakness, Speech difficulty, Time to call emergency services

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Metabolic and Endocrine Disorders

These conditions involve the body's inability to properly process energy or regulate hormones. Insulin resistance and chronic inflammation serve as the biological bridges connecting obesity, diabetes, and cardiovascular disease.

Diabetes (Type 1 and Type 2)

• Type 1 is autoimmune (immune system destroys insulin-producing cells), while Type 2 involves insulin resistance—critically different mechanisms requiring different management approaches
• Complications affect multiple organ systems—uncontrolled blood sugar damages blood vessels, leading to heart disease, kidney failure, blindness, and nerve damage
• Type 2 is largely preventable—lifestyle interventions (weight loss, exercise, diet) can prevent or delay onset in high-risk individuals by up to 58%

Obesity

• Defined by BMI ≥ 30—Body Mass Index calculated as weight in kg divided by height in meters squared
• Central adiposity (belly fat) poses greatest risk—visceral fat releases inflammatory chemicals that promote insulin resistance and cardiovascular disease
• Root cause of metabolic syndrome—obesity increases risk for diabetes, hypertension, heart disease, and certain cancers through shared inflammatory pathways

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Respiratory Conditions

These diseases affect the airways and lung tissue, limiting oxygen exchange. Chronic inflammation and airway obstruction—whether from environmental damage or immune overreaction—define this category.

Chronic Obstructive Pulmonary Disease (COPD)

• Progressive and irreversible lung damage—primarily caused by smoking (85-90% of cases), with emphysema and chronic bronchitis as the two main forms
• Spirometry confirms diagnosis—measures forced expiratory volume to assess airflow limitation; FEV1/FVC ratio below 70% indicates obstruction
• Smoking cessation is the only intervention that slows disease progression—medications manage symptoms but cannot reverse lung damage

Asthma

• Reversible airway obstruction—distinguishes it from COPD; airways narrow due to inflammation and muscle spasm but can return to normal
• Trigger identification is essential—allergens, exercise, cold air, and respiratory infections can provoke attacks in susceptible individuals
• Controller vs. rescue medications—daily anti-inflammatory inhalers prevent attacks, while bronchodilators provide emergency relief during acute episodes

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Neurological and Cognitive Conditions

These conditions involve progressive damage to brain tissue and nervous system function. Neurodegeneration—the gradual loss of neurons—currently cannot be reversed, making early detection and risk reduction critical.

Alzheimer's Disease

• Most common cause of dementia—accounts for 60-80% of dementia cases, characterized by amyloid plaques and tau tangles in brain tissue
• Progressive cognitive decline follows predictable stages—from mild memory loss to complete dependence for basic activities of daily living
• Non-modifiable risk factors dominate—age (risk doubles every 5 years after 65), family history, and APOE-e4 gene; however, cardiovascular health and cognitive engagement may offer some protection

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Musculoskeletal Conditions

These conditions affect joints, bones, and connective tissue, limiting mobility and quality of life. Inflammation—whether from mechanical wear or autoimmune attack—drives joint destruction across different arthritis types.

Arthritis

• Umbrella term for 100+ conditions—osteoarthritis (mechanical wear) and rheumatoid arthritis (autoimmune) are most common but have fundamentally different causes
• Osteoarthritis affects weight-bearing joints—results from cartilage breakdown; risk increases with age, obesity, and previous joint injury
• Rheumatoid arthritis is systemic—immune system attacks joint lining symmetrically (both hands, both knees), causing inflammation throughout the body

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Cellular Dysfunction

Cancer represents a fundamentally different disease mechanism—uncontrolled cell growth rather than organ system failure. Mutations in genes controlling cell division accumulate over time, eventually overriding the body's normal checks on cell reproduction.

Cancer

• Not one disease but hundreds—each cancer type has distinct risk factors, progression patterns, and treatment approaches based on tissue of origin
• Modifiable factors cause 30-50% of cases—tobacco (lung), UV exposure (skin), HPV (cervical), obesity (multiple types), and alcohol contribute to preventable cancers
• Early detection dramatically improves survival—screening programs for breast, cervical, colorectal, and lung cancers catch disease at treatable stages

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Quick Reference Table

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Self-Check Questions

1. Which two conditions share the most risk factors and are often described as part of metabolic syndrome? What biological mechanism connects them?

2. Compare and contrast COPD and asthma—what do they share, and what key feature distinguishes them? Why does this distinction matter for treatment?

3. Why is hypertension called the "silent killer," and which other chronic diseases does controlling blood pressure help prevent?

4. If an exam question asks you to identify a chronic disease caused by autoimmune dysfunction versus one caused by lifestyle factors, which conditions would you contrast? Explain the difference in prevention approaches.

5. A patient has obesity, Type 2 diabetes, and hypertension. Using the concept of shared risk factors and inflammatory pathways, explain why these conditions cluster together and what single intervention would address all three.