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Lesson 1: Abnormal Behavior

Frequency & Burden of Mental Disorders

Epidemiology = The academic study of the occurrence of various health issues in society.

Epidemiological data reveals how common or rare certain health conditions are.

The following epidemiological terms are very important to know, and you will need to know them throughout the entire course:

Incidence

Incidence = The onset or new occurrence of a given disorder over some period of time; the proportion of people who “get” a condition for the first time within a given year. This is always the smallest of the three numbers.

For example, in the United States, approximately 29,218 new cases of Hepatitis C occurred in 2013, which is approximately 1 out of every 10,918 people or .009% of the population (Centers for Disease Control & Prevention, CDC, 2016).

Prevalence

Prevalence = The % of people in a population who suffer from a disorder at a given point in time; the proportion of people who “have” the disorder right now, including both new and persisting cases.

For example, according to the CDC (2016), approximately 3.5 million Americans are believed to be currently infected with Hepatitis C; this is approximately 1% of the population.

Lifetime Prevalence

Lifetime Prevalence = The total proportion of people in a population who have ever had a certain condition at any point in their life, even if they’ve been cured and no longer have the condition. This is always the highest of the three numbers.

Hepatitis C is usually a chronic condition, so let’s switch to clinical mood disorders as an example. According to the Harvard Medical School (2007) the lifetime prevalence for a clinical mood disorder is approximately 21.4% of the American population, meaning that more than 1 out of every 5 Americans meets the criteria for a clinical mood disorder such as depression or bipolar.

 


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