Non-communicable diseases: causes, risk factors and prevention

What you'll learn

Non-communicable diseases (NCDs) are major health challenges in the Caribbean, accounting for over 70% of deaths in the region. This guide covers the causes, risk factors and prevention strategies for the key NCDs tested in CXC CSEC Human and Social Biology examinations. You will learn to distinguish between different types of NCDs, explain their underlying causes, and recommend evidence-based prevention measures relevant to Caribbean populations.

Key terms and definitions

Non-communicable disease (NCD) — a disease that cannot be transmitted from one person to another; often chronic and progressing slowly over time

Risk factor — a characteristic, condition or behaviour that increases the likelihood of developing a disease

Lifestyle disease — a disease associated with the way a person or group of people lives, including diet, physical activity levels, smoking and alcohol consumption

Hypertension — persistently high blood pressure (above 140/90 mmHg), placing strain on the cardiovascular system

Type 2 diabetes mellitus — a metabolic disorder characterized by high blood glucose levels due to insulin resistance or insufficient insulin production

Atherosclerosis — the accumulation of fatty deposits (plaques) on the inner walls of arteries, narrowing the blood vessels

Coronary heart disease (CHD) — disease of the blood vessels supplying the heart muscle, often caused by atherosclerosis

Body Mass Index (BMI) — a measure of body weight relative to height, calculated as weight (kg) ÷ height² (m²), used to classify overweight and obesity

Core concepts

Non-communicable diseases overview

NCDs differ fundamentally from communicable diseases because they cannot be spread through pathogens. They typically develop over extended periods and are strongly influenced by modifiable lifestyle factors.

Major NCDs in the Caribbean:

• Cardiovascular diseases (heart attacks, strokes, hypertension)
• Type 2 diabetes mellitus
• Chronic respiratory diseases (asthma, chronic obstructive pulmonary disease)
• Cancers (particularly lung, breast, prostate, colon and cervical)
• Kidney disease

Caribbean countries including Jamaica, Barbados, Trinidad and Tobago face particularly high rates of diabetes and hypertension. These conditions place significant burdens on regional healthcare systems and economies through lost productivity and treatment costs.

Characteristics of NCDs:

• Long duration and generally slow progression
• Not caused by infectious agents
• Often preventable through lifestyle modifications
• May have genetic predisposition factors
• Frequently linked to aging populations
• Can lead to serious complications if unmanaged

Cardiovascular diseases

Cardiovascular diseases affect the heart and blood vessels, representing the leading cause of death in the Caribbean region.

Hypertension (High Blood Pressure)

Blood pressure measures the force blood exerts on artery walls. Normal blood pressure is approximately 120/80 mmHg. Hypertension occurs when readings consistently exceed 140/90 mmHg.

Causes and risk factors:

• Excessive salt intake (common in Caribbean diets with processed foods and preserved meats)
• Obesity and overweight
• Physical inactivity
• Excessive alcohol consumption
• Chronic stress
• Genetic predisposition
• Age (risk increases after 45 years)
• Smoking

Hypertension damages arteries, forcing the heart to work harder. This increases risk of heart attacks, strokes, kidney disease and heart failure.

Atherosclerosis and Coronary Heart Disease

Atherosclerosis develops when fatty deposits accumulate in artery walls, forming plaques. These plaques narrow arteries, restricting blood flow and reducing oxygen delivery to tissues.

In coronary arteries supplying the heart muscle, atherosclerosis causes coronary heart disease. If a plaque ruptures, blood clots form, potentially blocking the artery completely and causing a myocardial infarction (heart attack).

Risk factors for atherosclerosis and CHD:

• High blood cholesterol (particularly LDL cholesterol)
• Hypertension
• Smoking (damages artery walls)
• Diabetes mellitus
• Obesity
• High saturated fat diet
• Physical inactivity
• Family history of heart disease

Stroke

A stroke occurs when blood supply to part of the brain is interrupted, either by a blocked artery (ischemic stroke) or burst blood vessel (hemorrhagic stroke). Brain cells deprived of oxygen die rapidly, causing permanent damage.

Strokes share similar risk factors with CHD, particularly hypertension, diabetes, smoking and atherosclerosis.

Diabetes mellitus

Type 1 Diabetes

Type 1 diabetes results from the immune system destroying insulin-producing beta cells in the pancreas. Without insulin, glucose cannot enter cells and accumulates in the blood. Type 1 diabetes typically develops in childhood or adolescence and requires lifelong insulin injections. It is not preventable and represents a smaller proportion of diabetes cases.

Type 2 Diabetes

Type 2 diabetes accounts for approximately 90% of diabetes cases in the Caribbean. It develops when cells become resistant to insulin or the pancreas cannot produce sufficient insulin to maintain normal blood glucose levels.

Causes and risk factors:

• Obesity (particularly abdominal fat)
• Physical inactivity
• High-sugar, high-carbohydrate diets (excessive consumption of sweetened beverages popular in Caribbean markets)
• Family history of diabetes
• Age (risk increases after 45 years)
• Ethnicity (higher prevalence in people of African and Indian descent)
• Previous gestational diabetes

Complications of uncontrolled diabetes:

• Cardiovascular disease (heart attacks and strokes)
• Kidney damage (diabetic nephropathy) leading to kidney failure
• Nerve damage (diabetic neuropathy) causing pain and numbness
• Eye damage (diabetic retinopathy) potentially causing blindness
• Poor wound healing and increased infection risk
• Foot ulcers and amputations

Caribbean countries experience particularly high rates of diabetes-related amputations and kidney disease.

Cancer

Cancer involves uncontrolled cell division producing malignant tumors that invade surrounding tissues and spread (metastasize) to other body parts.

Common cancers with lifestyle risk factors:

Lung cancer:

• Smoking (primary cause in 85-90% of cases)
• Secondhand smoke exposure
• Air pollution
• Occupational exposure to carcinogens (asbestos, radon)

Breast cancer:

• Family history and genetic mutations (BRCA1, BRCA2)
• Obesity after menopause
• Excessive alcohol consumption
• Physical inactivity
• Hormone replacement therapy

Colon cancer:

• High-fat, low-fiber diets
• Excessive red and processed meat consumption
• Obesity
• Physical inactivity
• Smoking and alcohol
• Age (risk increases after 50 years)

Cervical cancer:

• Human papillomavirus (HPV) infection (though HPV itself is communicable, cervical cancer is not)
• Smoking
• Weakened immune system
• Multiple sexual partners

Prostate cancer:

• Age (most common after 65 years)
• Family history
• African ancestry (higher risk)
• High-fat diets

Obesity as a major risk factor

Obesity represents one of the most significant modifiable risk factors for multiple NCDs. It is measured using Body Mass Index:

• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25.0-29.9
• Obese: BMI ≥30.0

Obesity particularly increases risk of:

• Type 2 diabetes
• Hypertension
• Coronary heart disease
• Stroke
• Certain cancers
• Osteoarthritis
• Sleep apnea

Causes of obesity:

• Energy imbalance (calorie intake exceeding expenditure)
• High consumption of energy-dense processed foods
• Large portion sizes
• Excessive sugar intake (particularly sweetened beverages)
• Physical inactivity
• Sedentary lifestyles
• Genetic factors
• Certain medications

Caribbean populations face rising obesity rates, partly attributed to nutrition transition toward processed foods and decreased physical activity levels.

Prevention strategies for NCDs

Dietary modifications:

• Reduce salt intake (avoid adding salt at table, limit processed foods)
• Decrease saturated fat consumption (limit fried foods, fatty meats, full-fat dairy)
• Increase fiber intake (more fruits, vegetables, whole grains, ground provisions like yam, cassava, dasheen)
• Reduce sugar consumption (limit sweetened beverages, desserts)
• Control portion sizes
• Choose healthier cooking methods (grilling, baking, steaming instead of frying)
• Increase consumption of fish (rich in omega-3 fatty acids)
• Include more legumes (red beans, black-eyed peas, pigeon peas)

Physical activity:

• Aim for at least 150 minutes of moderate-intensity aerobic activity weekly
• Include muscle-strengthening activities twice weekly
• Reduce sedentary time (limit screen time)
• Use active transportation (walking, cycling)
• Participate in Caribbean recreational activities (swimming, cricket, football, dancing)

Smoking cessation:

• Eliminate tobacco use completely
• Avoid secondhand smoke exposure
• Seek support through cessation programs
• Use nicotine replacement therapy if needed

Alcohol moderation:

• Limit consumption to recommended levels
• Avoid binge drinking
• Choose alcohol-free days weekly

Regular health screening:

• Blood pressure checks (annually for adults)
• Blood glucose testing (especially if overweight or family history)
• Cholesterol screening (every 4-6 years for adults)
• Cancer screening (mammograms, Pap smears, colonoscopy as recommended)
• BMI monitoring

Stress management:

• Practice relaxation techniques
• Ensure adequate sleep
• Maintain social connections
• Seek professional help when needed

Public health measures:

Caribbean governments implement various NCD prevention strategies:

• Food labeling regulations
• Taxes on sugar-sweetened beverages
• School nutrition programs
• Public education campaigns
• Smoke-free legislation
• HPV vaccination programs
• Physical activity promotion initiatives

Worked examples

Example 1: Structured question on diabetes

Question: Explain how lifestyle factors contribute to the development of Type 2 diabetes mellitus. (6 marks)

Model answer:

Obesity is a major risk factor because excess body fat, particularly around the abdomen, causes cells to become resistant to insulin [1 mark]. This means glucose cannot enter cells efficiently and blood glucose levels remain high [1 mark].

Physical inactivity contributes because exercise helps cells use glucose and increases insulin sensitivity [1 mark]. Without regular physical activity, glucose uptake is reduced and diabetes risk increases [1 mark].

Diets high in sugar and refined carbohydrates cause frequent blood glucose spikes [1 mark]. Over time, this can lead to insulin resistance and exhaustion of pancreatic beta cells [1 mark].

Example 2: Data interpretation question

Question: The table shows BMI categories and their associated risk for Type 2 diabetes:

(a) Calculate the BMI for a person weighing 90 kg with height 1.5 m. (2 marks) (b) State this person's risk category for Type 2 diabetes. (1 mark) (c) Suggest TWO lifestyle changes to reduce their diabetes risk. (2 marks)

Model answer:

(a) BMI = 90 ÷ (1.5)² [1 mark] = 90 ÷ 2.25 = 40 kg/m² [1 mark]

(b) Severely obese / 20 times higher risk than normal weight [1 mark]

(c) Any TWO from:

• Reduce calorie intake / eat smaller portions [1 mark]
• Increase physical activity / exercise regularly [1 mark]
• Reduce sugar and refined carbohydrate consumption [1 mark]
• Eat more fiber-rich foods / vegetables / ground provisions [1 mark]

Example 3: Prevention question

Question: A health educator is planning a campaign to reduce hypertension in a Caribbean community.

(a) State THREE dietary changes that could reduce hypertension risk. (3 marks) (b) Explain why reducing salt intake lowers blood pressure. (2 marks)

Model answer:

(a) Any THREE from:

• Reduce salt intake / avoid adding salt to food [1 mark]
• Reduce consumption of processed/preserved meats [1 mark]
• Increase intake of fresh fruits and vegetables [1 mark]
• Reduce saturated fat intake [1 mark]
• Reduce alcohol consumption [1 mark]

(b) High salt intake causes water retention in the blood [1 mark]. This increases blood volume, putting more pressure on artery walls / making the heart work harder [1 mark].

Common mistakes and how to avoid them

• Confusing Type 1 and Type 2 diabetes: Remember Type 2 is preventable through lifestyle changes and linked to obesity; Type 1 is autoimmune and not preventable. Exam questions about prevention specifically refer to Type 2.

• Listing symptoms instead of causes: When asked about causes or risk factors, focus on what increases disease likelihood (smoking, obesity, diet), not the effects (chest pain, fatigue, thirst). Read command words carefully.

• Vague prevention advice: Avoid general statements like "eat healthy" or "exercise more." Be specific: "reduce saturated fat intake," "engage in 150 minutes of moderate physical activity weekly," "limit sugar-sweetened beverage consumption."

• Forgetting the mechanism: Don't just state that smoking causes lung cancer; explain that tobacco contains carcinogens that damage DNA in lung cells, leading to uncontrolled cell division. Examiners reward mechanistic understanding.

• Confusing risk factors with causes: A risk factor increases likelihood but doesn't guarantee disease development. Family history is a risk factor, not a direct cause. Distinguish between modifiable (lifestyle) and non-modifiable (age, genetics) risk factors.

• Ignoring mark allocation: If a question is worth 4 marks, provide 4 distinct points. One-word answers rarely earn full marks unless specifically requested.

Exam technique for "Non-communicable diseases: causes, risk factors and prevention"

• Command word awareness: "State" requires brief answers; "Explain" demands reasoning with cause and effect; "Suggest" allows multiple valid responses. "Distinguish" requires clear differences between concepts. Allocate time according to marks available.

• Use Caribbean context appropriately: When discussing dietary changes, reference relevant foods (ground provisions, callaloo, local fruits) rather than only generic terms. This demonstrates applied knowledge but don't force it where unnecessary.

• Structure prevention questions systematically: Organize answers by category—dietary changes, physical activity, screening, smoking cessation. This ensures comprehensive coverage and prevents repetition.

• Link risk factors to mechanisms: Don't just list that obesity increases diabetes risk; explain insulin resistance or pancreatic stress. Higher-mark questions reward understanding of biological processes, not just memorization.

Quick revision summary

Non-communicable diseases cannot spread between people and develop slowly, often due to lifestyle factors. Major NCDs include cardiovascular diseases (hypertension, CHD, stroke), Type 2 diabetes, cancers and chronic respiratory diseases. Key risk factors are obesity, poor diet (high salt, sugar, saturated fat), physical inactivity, smoking and excessive alcohol. Prevention focuses on healthy eating, regular physical activity, maintaining healthy weight, avoiding tobacco, moderating alcohol and regular screening. Caribbean populations face particularly high NCD burdens, making prevention crucial for individual and public health.