Psychological Disorders

15.1 Section Title

Topic: Comorbidity: The relationship between related disorders

Statistical Concepts Covered: In this applet, you’ll learn more about relationships by looking at comorbidity or the prevalence of having two disorders at the same time. We will also discuss the importance of operational definitions.

Introduction

Your text chapter discusses various mental disorders and their symptoms, as well as the impact these disorders have on individuals. The data for this applet comes from the National Comorbidity Survey (NCS), detailed interviews conducted on a nationally representative sample to determine whether individuals exhibited symptoms of various disorders. Our analysis of this data will focus on comparing the prevalence of these disorders and their comorbidities, the rates at which individuals experience two disorders at the same time.

Richard Alan Hullinger, Indiana University, Bloomington
Melanie Maggard, University of the Rockies

Statistical Lesson. In previous applets we considered correlations and how we use them to look at a relationship between two variables. These variables were sometimes numerical and sometimes categorical. In the case with comorbidity we are looking at categories again because we are evaluating how many people fit into two categories or disorders at the same time. This is what we refer to as comorbidity, the presence of two disorders in an individual at the same time.

When identifying variables within a study it is important that we have operational definitions, which explain how we will manipulate or measure our variables. In the case of comorbidity there might be two ways we can define how we are measuring a person’s experience of two disorders during the same time period.

First, we may choose to operationally define someone as having comorbidity for two disorders if they experience both within a 12 month period, which we will refer to as 12 month prevalence in this applet. Second, we may choose to operationally define someone as having comorbidity if they experience two disorders at any point in their lifetime, which we will refer to as lifetime prevalence.

It is important to distinguish between these two as they can lead to very different interpretations. Be sure to keep this in mind when answering the questions in this applet. Think about how the time frame being used to define the comorbidity may lead us to different conclusions. As a reminder, any analysis of relationships should focus only on that relationship and not imply causality.

Question

1) Which disorders have the highest and lowest lifetime prevalence rates? (Choose to show “lifetime prevalence”.)

The highest prevalence rate was MDD at 7%, while conduct disorder had the lowest rate at 0.35%.

The highest prevalence rate was specific phobia at 9%, while conduct disorder had the lowest rate at 0.35%.

The highest prevalence rate was alcohol abuse at 11%, while both Bipolar I and II had the lowest rates at 1% each.

The highest prevalence rate was MDD at 17%, while both Bipolar I and II had the lowest rates at 1% each.

Correct.

Incorrect.

Question

2) How does the lifetime comorbidity for Bipolar I differ from Bipolar II? (Choose to show “lifetime comorbidity”, and cycle through selecting “Bipolar I” and “Bipolar II” for the field.)

These disorders have no comorbidity with each other, nor with MDD. However, Bipolar I had much higher comorbidity rates (40%) for social and specific phobias than Bipolar II.

These disorders have no comorbidity with each other, nor with MDD. However, Bipolar I had higher comorbidity rates with social and specific phobias than Bipolar II.

These disorders have no comorbidity with each other, nor with MDD. However, Bipolar I had much higher comorbidity rate for several disorders than Bipolar II, including alcohol abuse, conduct disorder, and IED.

These disorders have high comorbidity with each other, and with MDD. However, Bipolar I had lower comorbidity rates with social and specific phobias than Bipolar II.

Correct.

Incorrect.

Question

3) Based on the analysis in question 2 and what you’ve learned from the chapter, what explanation is there for the lack of comorbidity between Bipolar I, Bipolar II, and MDD?

Being diagnosed with one of these disorders would exclude a person from being diagnosed with one of the other disorders. If one has Bipolar I, then Bipolar II is also present, for example.

These disorders are very similar but we should not record individuals multiple times when they are diagnosed with two or three of these disorders at the same time.

These disorders are completely different, so there is no overlap or comorbidity possible.

Being diagnosed with one of these disorders would exclude a person from being diagnosed with one of the other disorders. One either has Bipolar I or II but not both, for example.

Correct.

Incorrect.

Question

4) Which disorder has the highest lifetime comorbidity rate with another disorder? (Choose to show “lifetime comorbidity”, and cycle through selecting the various disorders for the field. Make a note of the highest prevalence for each disorder.)

Dysthymia with Bipolar II at 70%.

Bipolar I with alcohol abuse at 55%.

GAD with specific phobia at 58%.

Dysthymia with MDD at 70%.

Correct.

Incorrect.

Question

5) What percentage of people in the population may have GAD and specific phobia during their lifetime? (Choose to show “lifetime prevalence”, and then show “lifetime comorbidity” while selecting “GAD” for the field.)

57% since this is the lifetime comorbidity rate for GAD and specific phobia.

46% since this is approximately 8% (lifetime prevalence of GAD) of 57% (comorbidity rate for the two disorders).

5% since this is approximately 57% (comorbidity rate for the two disorders) of 8% (lifetime prevalence of GAD).

8% since this is the lifetime prevalence rate for GAD.

Correct.

Incorrect.

Question

6) Which disorders have the highest and lowest 12 month prevalence rates? (Choose to show “12 month prevalence”.)

The highest prevalence rate was MDD at 7%, while conduct disorder had the lowest rate at 0.35%.

The highest prevalence rate was specific phobia at 9%, while conduct disorder had the lowest rate at 0.35%.

The highest prevalence rate was specific phobia at 9%, while both Bipolar I and II had the lowest rates at 1% each.

The highest prevalence rate was MDD at 17%, while both Bipolar I and II had the lowest rates at 1% each.

Correct.

Incorrect.

Question

7) Which disorder has the highest 12 month comorbidity rate with another disorder? How does this compare with the disorders with the highest lifetime comorbidity rate? (Choose to show “12 month comorbidity”, and cycle through selecting the various disorders for the field. Make a note of the highest prevalence for each disorder. Compare your answer to question 4.)

Bipolar I with social phobia at 42%, which is higher than the highest rate for lifetime comorbidity of 32% between alcohol abuse and IED.

Dysthymia with MDD at 70%, which was also the highest rate for lifetime comorbidity.

ADD with specific phobia at 35%, which was lower than the highest rate for lifetime comorbidity of 70% between dysthymia and MDD.

Dysthymia with Bipolar II at 70%, which was also the highest rate for lifetime comorbidity.

Correct.

Incorrect.

Question

8) Compare the comorbidity rates for ADD over the lifetime and during 12 months. Which disorder has the highest comorbidity rate with ADD? (Choose to show “12 month comorbidity”, and select “ADD” for the field. Compare this graph to when “lifetime comorbidity” is shown.)

ADD has the highest 12 month comorbidity rate with social phobia, but over the lifetime social phobia is second to ODD’s comorbidity rate with ADD.

ADD has the highest 12 month and lifetime comorbidity rate with social phobia.

ADD has the highest 12 month comorbidity rate with specific phobia, but over the lifetime social phobia is second to alcohol abuse’s comorbidity rate with ADD.

ADD has the highest 12 month comorbidity rate with ODD, but over the lifetime social phobia has the highest comorbidity rate with ADD.

Correct.

Incorrect.

Question

9) What percentage of people in the population may have GAD and specific phobia over 12 months? How does this differ from the number obtained in question 5 for these disorders over one’s lifetime? (Choose to show “12 month prevalence”, and then show “12 month comorbidity” while selecting “GAD” for the field.)

4% since this is the 12 month prevalence rate for GAD; this is about the same as the percentage over the lifetime.

1% since this is approximately 30% (comorbidity rate for the two disorders) of 4% (12 month prevalence of GAD); this is lower than the percentage over the lifetime.

30% since this is the 12 month comorbidity rate for GAD and specific phobia; this is much higher than the percentage over the lifetime.

12% since this is approximately 4% (12 month prevalence of GAD) of 30% (comorbidity rate for the two disorders); this is much higher than the percentage over the lifetime.

Correct.

Incorrect.

Question

10) Based on what you’ve learned from the data explored in this applet and the readings in the chapter on psychological disorders, what would be the best conclusion we can reach regarding the relationship between these disorders in terms of comorbidity and their prevalence?

Most people never experience a disorder in their lifetime but may experience multiple in a 12 month period.

Having any disorder makes someone have other disorders as well, with most people experiencing at least one disorder in their lifetime.

Most people will have multiple disorders over the short-term, such as 12 months, but not over the long-term, such as their lifespan.

If an individual has one of these disorders, he or she may be more likely of having another disorder within 12 months or their lifetime.

Correct.

Incorrect.

Chapter 15. Psychological Disorders

15.1 Section Title

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