PSYCH 134 Lecture 5

Epidemiology
The study of disease
– Incidence
-Prevalence
-Determinants

Epidemiologists- are scientist devoted to the study of health *determinants,* the *distribution* of disease in communities, and the *validity of disease risk factors.*

Descriptive Epidemiology
Description of outcomes (e.g sickness, death and likely *determinants* , placed within appropriate contexts of person, place, & time.

Ex. John Snow

Inferential Epidemiology
– Related to *inferential statistics*
– *The methods to estimates characteristics of a population on the basis of a sample.*

– Characteristic of the population at all levels (person,place, and time) must be operationalized so that they can be assessed with quantitative (statistical methods.
– Utilizes measures of correlation (covariation) of strength of relationshiop and various statistics (F,t, chi- schi-square) for determining the likelihood that something occurred by chance.

Behavioral Epidemiology
To Describe the study of *individual behaviors* and *habits* in relation to health outcomes.

It has the explicit purpose of understanding and influencing healthful *behavioral patterns*, as part of population wide initiatives to prevent diseases and promote health.

Ex. smoking ,diet, exersice.

Health Behavior and Inflammation
The main point of this study was there there was an *indirect effect* of early adversity on inflanmation. it has to go trough something more to see a *** effect.

Early adversity—–> bad health behavior choices—–> bad outcomes

There was 99% of what we would know does not have to do with early adversity.
— This was not a very strong prediction of this.
+They had a good sample size.
+Good data, over a 20 year period.

Incidence formula
– The number of cases within a specific period of time.

Incidence rate per 1,000=

New cases per unit of time/ Persons exposed or at risk per unit of time *1,000

Prevalence formula
– the number of cases at any point in time.

Cases at specific time point/ Persons at exposed or at risk at specific time point * 1,000

Longitudinal Study Types
1. Cohort Studies
2. Panel Studies

Cohort Studies
In this studies, groups of people who share *common* characteristics are followed over the course of time. These studies, which are often *prospective,* resample the same sample population on repeated occasions. However, the exact participants in the study may not be the same on repeated observations.

Panel Studies
*Prospective*

This studies have the stricter requirements that the same individuals in the original sample are followed at each repeated assessment.

Cross-sectional Studies
They examine different groups of individuals at the same point in time.

Ex. Inferences on drug use in college.
They same sample from Freshman, Jrs, Seniors.

Case- Control
_Typically *Retrospective & cross-sectional*

A selected group with a targeted diseases is compared to those w/out the disease.

Experimental Studies
– Systematic manipulation of variable(s)
-Its difficult to determining the effects of an intervention is that they intervection may occur at a crisis times.

– Hard to implement at epidemiological scale.

Ex. Chinese Stroke Prevention Trail

Major Epidemiological Studies
1. Framingham Heart Study
2. Alameda County population Study
3. China Stroke Prevention Trial.

Framingham Heart Study
The purpose of the study was to determine the causes of stroke and heart failure.

A major finding of the study was that some of the best predictors of health disease and early death are direct consequences of own behaviors.
– Smoking, obesity, high cholesterol levels, physical inactivity, and possible excessive tention and stress.

Alameda County Study
They found systematic relationships between the number of activities and the mordity and mortality.

It also broke new going by demostraiting the relationship between social support and health outcomes.

-sleep
-alcohol
-exercise
-Smoking
-Soc. Support

Those who are more “socially connected”, had significantly greater chances of survival than those who are less connected.

China Stroke prevention trial
It was a community- based intervention trial was designed and implemented in major urban areas of Beijing, Shanghai, and Changsha.
It each urban are, one community was choosen as the intervention site and the other as the control site.
They received health education and health promotions services to help participants to avoid cigars and control blood pressure.

Time
It is important to consider in 2 ways:
— Time Course
–Rate (of change)
-* time course* will affect decision about study design and interpretation of findings.
*Rate of change * will inform the relatively stability or growth in a disease or behavior.

—AIDS epidemic in 1980’s

Place
The relationship between Sunlight exposure and the development of cancer.
However, Sunlight is also an important source of vitammin D, and some cancers may be related to deficiencies in this important vitamin