Prevalence and Comorbidity: Videos & Practice Problems

Prevalence refers to the proportion of a population with a specific disorder at a given time, categorized into point prevalence (current cases) and lifetime prevalence (cases over a lifetime). For instance, in 2021, 8% of U.S. adults had major depression, while 19% had an anxiety disorder. Comorbidity occurs when individuals have multiple disorders simultaneously, often leading to worse outcomes. Common comorbidities include depression with anxiety (20-70%) and PTSD (50%). Understanding these concepts is crucial for recognizing the complexities of mental health disorders.

Prevalence and Comorbidity

In this video, we're going to be talking about prevalence and comorbidity. So prevalence is essentially the proportion of the population that has a given characteristic, or in our case, a disorder, within a specific time period. And there are two types of prevalence that we discussed. We talk about point prevalence and lifetime prevalence. So point prevalence is essentially the percentage of people who have a condition at a specific point in time.

So we could look at a certain year and say what percentage of the population was diagnosed with this disorder. To give you an example of this, looking at the 2021 survey done by the National Institute of Mental Health, what they were able to show was that, in that year, about eight percent of adults in the United States had been diagnosed with major depression, and about nineteen percent had been diagnosed with an anxiety disorder. And to be clear, when I say anxiety disorder, that is a broad category. It involves multiple different diagnoses, which is why that number looks so much higher than the depression number. We're just accounting for more things there.

So that's an example of point prevalence. We're looking at in this year, what percentage of the population received that diagnosis. Now, we can also talk about lifetime prevalence. So lifetime prevalence is essentially the percentage who have a condition within their lifetime. To give you an example from that same survey done by the National Institute of Mental Health, they were able to show that on average, we would expect about twenty percent of US adults to be diagnosed with depression at some point in their lifetime and about thirty-one percent of US adults to be diagnosed with an anxiety disorder, again, at some point in their lifetime.

So these aren't too tricky to understand. They have nice intuitive names, but it is important to be aware of which one you are looking at because as you can see the numbers can look quite different. So anytime you're looking at any kind of prevalence rates just kind of be aware of if you're looking at a point prevalence rate or a lifetime prevalence rate. Alright, so that is prevalence and now we're going to move on to comorbidity. So comorbidity is pretty much what it sounds like.

We have that prefix co- there which means togetherness or jointness. So this is essentially when we have the simultaneous occurrence of two or potentially even more disorders. So this is when a person has been diagnosed with two or more disorders at the exact same time, and comorbidity is quite common. I'm going to give you some example comorbidity rates in just one moment, but it's important to be aware of because people who have comorbid diagnoses often have worse outcomes. You know, they can be experiencing double or even triple the symptoms that can make these disorders, you know, even more distressing for the person.

They can be impacting the person's functioning and the person's life, even more than a single diagnosis might. So comorbidity can lead to worse outcomes, so it's very important to be aware of. And like I said, it can be quite common. So we're going to look at some example comorbidity rates. You don't have to know these or memorize these, but just to give you kind of a sense of what I'm talking about here.

So depression and anxiety tend to be highly comorbid. Depending on the sample that we're looking at, rates can be between about twenty to seventy percent of the sample having a comorbid diagnosis so that is obviously quite high. Another common one that we see is depression and PTSD. We often see comorbidity rates of about fifty percent with those disorders. Autism spectrum disorder and ADHD are highly, highly comorbid.

Rates are usually going to be between fifty to seventy percent depending on the sample. And another very common one is substance abuse and depression. Again, depending on the sample we'll see rates between like thirty-six to forty-three percent a lot of the time. And as you can see all of these do include citations, so if you look on your worksheet you'll find all of those references if you want to check out any of this research for yourself. Alright, so that is prevalence and comorbidity and I will see you guys in the next one.

Bye bye.

Example 1

Alright. So when we're looking at data for prevalence, which is likely to be higher, the point prevalence or the lifetime prevalence? And then how do we explain that? So keep in mind, when we're thinking about lifetime prevalence, we're thinking about the proportion of people who have ever experienced mental illness at any point in their lives. Whereas when we're thinking about point prevalence, we're thinking about the number of people who experience a mental illness at a specific point in time, for example, within a specific year.

So generally speaking, we expect lifetime prevalence rates to look a little bit higher and that's because we're just accounting for a lot more years there. We're just accounting for more time. So more people are going to have a disorder within their full lifetime than at a specific point in time. Okay? It's just like probability.

We're just accounting for more years there. So that number is typically going to be higher. There can be exceptions, but that's the general trend that we would expect to see. Alright, and there you have it, and I will see you in the next one. Bye bye.

An individual has a comorbidity when ...

• A. A psychological disorder becomes chronic.
• B. Two or more psychological disorders are present at the same time.
• C. They are diagnosed with any health condition.
• D. Their risk of dying from the psychological disorder increases.

Answer: (B)

Here’s what students ask on this topic:

What is the difference between point prevalence and lifetime prevalence in mental health disorders?

Point prevalence and lifetime prevalence are two ways to measure how common a mental health disorder is within a population. Point prevalence refers to the percentage of people who have a disorder at a specific point in time. For example, in 2021, 8% of U.S. adults were diagnosed with major depression. Lifetime prevalence, on the other hand, measures the percentage of people who will have a disorder at any point in their lives. For instance, about 20% of U.S. adults are expected to be diagnosed with depression at some point in their lifetime. Understanding these distinctions is crucial for interpreting data on mental health disorders, as point prevalence provides a snapshot of current cases, while lifetime prevalence offers a broader view of the disorder's impact over time.

Why is comorbidity important in understanding mental health disorders?

Comorbidity is crucial in understanding mental health disorders because it refers to the simultaneous occurrence of two or more disorders in an individual. This is important because comorbid conditions often lead to more severe symptoms and worse outcomes compared to having a single disorder. For example, depression and anxiety are highly comorbid, with rates ranging from 20% to 70%. Comorbidity can complicate diagnosis and treatment, as overlapping symptoms may require integrated therapeutic approaches. Additionally, individuals with comorbid disorders may experience greater functional impairment, affecting their daily lives and overall well-being. Recognizing comorbidity helps mental health professionals develop more effective treatment plans and provides a more comprehensive understanding of the complexities involved in mental health disorders.

How common is the comorbidity of depression and PTSD?

The comorbidity of depression and PTSD (Post-Traumatic Stress Disorder) is relatively common, with rates often around 50%. This means that about half of the individuals diagnosed with either depression or PTSD may also meet the criteria for the other disorder. The high comorbidity rate can be attributed to overlapping symptoms such as mood disturbances, anxiety, and difficulties in functioning. Understanding this comorbidity is important for mental health professionals, as it can influence the course and treatment of both disorders. Integrated treatment approaches that address both depression and PTSD simultaneously may be more effective in improving outcomes for individuals experiencing these comorbid conditions.

What are some examples of highly comorbid mental health disorders?

Several mental health disorders are known to be highly comorbid, meaning they frequently occur together. Some common examples include depression and anxiety, with comorbidity rates ranging from 20% to 70%. Depression and PTSD also have a high comorbidity rate of about 50%. Autism Spectrum Disorder and ADHD are another pair of disorders that often co-occur, with rates between 50% to 70%. Additionally, substance abuse and depression frequently occur together, with comorbidity rates ranging from 36% to 43%. Understanding these comorbidities is essential for mental health professionals, as they can complicate diagnosis and treatment, requiring integrated approaches to address the complex needs of individuals with multiple disorders.

How does comorbidity affect the treatment and outcomes of mental health disorders?

Comorbidity can significantly affect the treatment and outcomes of mental health disorders. When individuals have multiple disorders simultaneously, they often experience more severe symptoms and greater functional impairment. This can complicate diagnosis, as overlapping symptoms may obscure the presence of each disorder. Consequently, treatment plans need to be more comprehensive and integrated, addressing all co-occurring conditions. Comorbid disorders may require a combination of therapeutic approaches, such as medication, psychotherapy, and lifestyle interventions, to effectively manage symptoms. Additionally, comorbidity can lead to worse outcomes, as the presence of multiple disorders can exacerbate the impact on an individual's daily life and overall well-being. Understanding and addressing comorbidity is crucial for improving treatment efficacy and patient outcomes.