2.3 Public Health and Disease Epidemiology

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Questions and Answers

What does the incidence rate of a disease specifically measure?

The number of new cases of a disease reported during a specific time period. (correct)

The total number of people affected by a disease at a specific point in time.

The proportion of a population affected by a disease.

The number of deaths caused by the disease in a specific time period.

Which of the following best describes the relationship between prevalence and incidence rates?

Prevalence rate is usually lower than the incidence rate.

Prevalence rate is usually higher than the incidence rate. (correct)

Prevalence rate is usually the same as the incidence rate.

Prevalence rate is not related to the incidence rate.

What does a relative risk value of 24 for lung cancer in heavy smokers, compared to non-smokers indicate?

Smokers have a 24% chance of developing lung cancer, and non-smokers do not.

The number of people who develop lung cancer is 24 times higher in smokers compared to non smokers.

The rate of lung cancer death is 24 times higher in heavy smokers compared to non-smokers. (correct)

The risk of lung cancer is 24 times lower for heavy smokers.

If a disease is common in one population but rare in another, what is most suggested by this?

The disease is likely influenced by a combination of environmental factors and lifestyle. (C) Signup and view all the answers

If the rates of stomach cancer have decreased among Japanese immigrants in the US, and colon cancer rates have increased, what does this suggest?

Environmental factors significantly impact the incidence of both types of cancer. (C) Signup and view all the answers

A disease is observed to have a higher prevalence rate than incidence rate. What can be inferred from this observation?

The disease is usually a chronic one, which people live with for years. (D) Signup and view all the answers

When determining the risk of a disease, what role do genes play in the context of exposure to tobacco smoke?

Variants in genes that are involved in the metabolism of tobacco smoke can increase or decrease the individual's risk of disease. (A) Signup and view all the answers

Which of the following is NOT considered a lifestyle-related risk factor for disease?

Family history (A) Signup and view all the answers

What is the primary risk factor associated with obesity?

Dietary habits (B), Environmental factors (C), Lack of physical activity (D) Signup and view all the answers

Which condition is characterized by progressive dementia and memory loss?

Alzheimer's disease (C) Signup and view all the answers

What percentage of the population over 65 is affected by Alzheimer's disease?

5 to 10 percent (B) Signup and view all the answers

What is the concordance rate for monozygotic twins with a history of alcoholism?

In excess of 60 percent (A) Signup and view all the answers

Which disorder is known for having a recurrence risk of 8 to 10 percent if one parent is affected?

Schizophrenia (B) Signup and view all the answers

What factor is primarily associated with early onset alcoholism?

Genetic inheritance (D) Signup and view all the answers

What is the likelihood of developing schizophrenia when both parents are affected?

50 percent (B) Signup and view all the answers

Which condition has a concordance rate of approximately 40 percent in monozygotic twins?

Schizophrenia (B) Signup and view all the answers

What is a significant environmental factor that can affect the development of psychological disorders?

Lifestyle choices (B) Signup and view all the answers

What genetic factor has been found to influence susceptibility to alcohol addiction?

GABA receptor genes (C) Signup and view all the answers

Which one of the following is NOT typically associated with Alzheimer's disease?

Bipolar moods (C) Signup and view all the answers

Which psychological disorder has the general population affected rate of about 0.5 percent?

Bipolar disorder (A) Signup and view all the answers

What typically indicates a higher genetic influence on a disorder?

Earlier age of onset (C) Signup and view all the answers

What component is essential in reducing risks for genetic disorders?

Environmental manipulation (C) Signup and view all the answers

What is a defining characteristic of multifactorial inheritance?

It involves the combined effects of multiple genes and environmental factors. (B) Signup and view all the answers

Which of the following statements about twin studies is true?

Concordance rates for diseases can indicate genetic influence. (A) Signup and view all the answers

What is the recurrence risk for multifactorial diseases compared to single gene diseases?

It is typically higher when more family members are affected. (A) Signup and view all the answers

How do dizygotic twins differ from monozygotic twins genetically?

Dizygotic twins are genetically different from each other. (A) Signup and view all the answers

What does a higher concordance rate in monozygotic twins suggest about a trait?

The trait has a strong genetic component. (A) Signup and view all the answers

In the context of multifactorial traits, what is the significance of environmental factors?

They can modify the expression of a polygenic trait. (D) Signup and view all the answers

What happens to the recurrence risk for multifactorial diseases in more distant relatives?

It decreases quickly compared to single gene diseases. (A) Signup and view all the answers

What was the historical view of twin studies as research tools?

They were considered perfect without environmental concerns. (C) Signup and view all the answers

Why might monozygotic twins show discordance for certain traits?

Environmental factors play a significant role. (B) Signup and view all the answers

What does a study reveal if adopted children of parents with a disease develop that disease more often than the control population?

It provides evidence that genetic factors may contribute to that disease. (A) Signup and view all the answers

What common misconception exists about monozygotic twins?

They exhibit more variations due to environmental differences. (A) Signup and view all the answers

In multifactorial diseases like diabetes, what type of conditions are influenced by the combination of genetic and environmental factors?

Multiple adult diseases and conditions. (A) Signup and view all the answers

What does the threshold of liability concept refer to in multifactorial diseases?

The genetic threshold required for disease to manifest. (D) Signup and view all the answers

What is a major influence in the expression of traits like blood pressure?

Both genetic inheritance and lifestyle choices. (B) Signup and view all the answers

What is the risk increase for an individual with a positive family history of coronary heart disease?

2 to 7 times more likely (C) Signup and view all the answers

What is the main contributor to the development of Type 1 diabetes?

Autoimmune response (C) Signup and view all the answers

Which factor is least likely to increase the risk of developing coronary heart disease?

Exercise (C) Signup and view all the answers

What percentage of breast cancer cases is accounted for by BRCA1 and BRCA2 mutations?

5 to 10 percent (D) Signup and view all the answers

Which of the following is a key risk factor for Type 2 diabetes?

Positive family history (C) Signup and view all the answers

Which condition is associated with a 20 to 50 percent lifetime risk due to a BRCA1 mutation?

Ovarian cancer (C) Signup and view all the answers

Environmental factors play an important role in the development of which disease?

Coronary heart disease (B) Signup and view all the answers

What is a characteristic of Type 2 diabetes?

Insulin resistance (B) Signup and view all the answers

For colorectal cancer, what is the effect of having one affected first-degree relative?

Risk increases two to three times (D) Signup and view all the answers

What is the concordance rate for identical twins with Type 1 diabetes?

30 to 50 percent (A) Signup and view all the answers

Congenital malformations can be considered multifactorial disorders that are:

Present at birth (A) Signup and view all the answers

What is a significant environmental risk factor for hypertension?

Sedentary lifestyle (A) Signup and view all the answers

What is the lifetime breast cancer risk for women with a BRCA2 mutation?

50 to 80 percent (D) Signup and view all the answers

What is the prevalence range of hypertension worldwide?

25 to 30 percent (A) Signup and view all the answers

Study Notes

Incidence and Prevalence of Diseases

Incidence rate: Number of new disease cases in a specific period (typically one year).
Prevalence rate: Proportion of a population affected by a disease at a specific time. Prevalence is usually higher than incidence. Factors like disease survival duration affect the comparison.

Risk Factors

Relative risk: Increased disease rate among exposed individuals compared to unexposed individuals. Calculated as (exposed/unexposed)
Example: Lung cancer study showed a 24-fold increased risk of death for heavy smokers compared to non-smokers.
Risk factors can be genetic (e.g., genes involved in tobacco metabolism) or lifestyle-related (e.g., age, gender, diet, exercise, family history).

Multifactorial Inheritance

Multifactorial traits: Variation caused by combined effects of multiple genes and environmental factors.
Examples: Height, blood pressure, many adult diseases (e.g., hypertension, heart disease, diabetes, some cancers).
Threshold of liability: Diseases where presence or absence is determined by multiple genes and environmental variables. This sometimes presents a distinct threshold where disease develops. Examples include pyloric stenosis, where rates differ by sex.

Recurrence Risk and Transmission

Recurrence risk increases if multiple family members are affected.
Recurrence risk is influenced by severity of the disease in affected family members.
Risk is higher if less commonly affected sex is affected.
Recurrence risk decreases more rapidly for multifactorial diseases compared to single-gene diseases as you move further out in family relationships.

Twin and Adoption Studies

Twin studies help separate genetic and environmental factors in disease risk.
Monozygotic (identical) twins share identical genes; differences in their traits are due to environmental factors.
Dizygotic (fraternal) twins share similar environmental factors but have different genes, similar to siblings.
Concordance rate: Percentage of twin pairs where both members share a trait.
Adoption studies: Examine whether children adopted to households without a disease develop the disease. Evidence is that similar genetic effects are seen compared with the biological parent who developed the disease.

Common Diseases with Genetic and Environmental Factors

Diseases like heart disease, cancer, diabetes, and others, are a combination of genetic and environmental factors.
Genetic susceptibilities may be heightened risk factors as opposed to being necessarily causational of the disease.
Lifestyle factors (diet, exercise) can drastically influence disease risk.
Examples of Multifactorial Diseases:
- Heart disease
- Cancer (various types)
- Diabetes (Type 1 and Type 2)
- Obesity (familial component but environmental impact is key)
- Alzheimer's disease
- Alcoholism
- Schizophrenia
- Bipolar disorder

Specific Disease Details

Heart disease: Leading killer in the US; risk factors include obesity, smoking, hypertension, high cholesterol, and family history (2-7x increased risk if a first-degree relative is affected)
Cancer: Genetic and environmental factors are involved; tobacco use is a significant factor (1/3 of cases). Specific cancers:
- Breast cancer: Common in women, risk doubled with an affected first-degree relative. BRCA1/2 genes increase risk.
- Colorectal cancer: Second most deadly cancer. Risk 2-3 times higher in affected first-degree relatives.
- Prostate cancer: Second most common cancer in men. Risk 2-3 times higher.
Type 1 diabetes: Autoimmune disorder (genetic or environmental trigger?).
Type 2 diabetes: Insulin resistance, common in obese individuals; risk influenced by family history and obesity.
Alzheimer's disease is a progressive disorder and is characterized by genetic and environmental interplay; genetics is most prominent in early cases. Risk increases with older age and first-degree family history.
Alcoholism has both genetic and environmental components. Some genes affect alcohol metabolism. Risk increased in blood relatives.
Schizophrenia has a strong genetic component; risk significantly higher in relatives with schizophrenia.
Bipolar disorder is influenced by both genetics and environment. Risk increases with affected first-degree relatives.

Further Considerations

Identifying specific genetic factors related to diseases can lead to better preventive measures and treatment strategies.
Lifestyle modifications (diet, exercise, stress reduction) are key for reducing the risk of many diseases, especially for individuals with a genetic predisposition.

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Description

Explore the concepts of incidence and prevalence of diseases, along with the risk factors associated with them. This quiz delves into multifactorial inheritance and the complex interactions between genetic and environmental influences on health. Test your knowledge of public health essentials and understanding of disease dynamics.