Defining and Diagnosing Clinical Depression

Michael E. Thase, MD: In modern parlance, people can say they’re depressed when they’re unhappy or disappointed or feel thwarted or defeated. It’s almost become a synonym for sadness or disappointment. But in clinical practice, the term refers to a syndrome, or a group of signs and symptoms that have hung together and come on together over some period. And so, the term a major depressive episode refers to a syndrome that’s at least 2 weeks in duration and includes at least 5 key symptoms. There are 9, more or less, symptoms that are possible to define an episode of major depression, and you need to have 5 of them, including a depressed mood and/or a loss of interest or a sense of inability to experience pleasure as one of the defining symptoms; and then at least 4 more. And to meet the syndrome or criteria, these symptoms need to be experienced almost every day across a several-week period.

Now, some people oversleep when they’re depressed, but more people have trouble falling asleep or staying asleep, or waking up early in the morning. Similarly, some people overeat, and a few even gain weight with an episode of depression. But more often, depression blunts your repetitive desires. People will lose appetite, and then more severe depression will have an impact of significant weight loss.

Before 1980, the definitions of the depressive disorders were relatively brief and almost stereotypic. Many depressions experienced by people in the outpatient world were thought to be part of a neurotic condition. Since 1980, we’ve gone from thinking about neurosis to thinking about disorders. And so, a major depressive disorder would be defined when someone has a major depressive episode that’s not caused by some other medical condition, or is not part of having schizophrenia, and our person who’s suffering from this depressive episode does not have a past history of mania or hypomania. Then, their major episode would be part of bipolar disorder.

I mentioned 1980 as a touchstone, because that was when the DSM-3 [Diagnostic and Statistical Manual of Mental Disorders, Third Edition] was published, and that’s when the fully spelled out ways of diagnosing the illness became part of our standard nomenclature. Since then, there have been 2 major revisions, and some smaller revisions in between. And so, since 2013, we’ve had the DSM-5. In the DSM-5, the basic definition of a major depressive episode has stayed pretty much the same as it was in 1980, although some of the subtypes, some of the subsets of classification have changed over time.

For example, whether the depression is seasonal or whether it’s associated with postpartum onset, and so forth, the instances are now called episode specifiers. These were subtypes of depression 20, 30 years ago. It’s just a way in which the nomenclature has evolved.

Over the last 20 years, so much more of depression treatment has fallen under the purview of primary care providers, including primary care physicians and primary care advanced nurse practitioners. And even physician’s assistants are involved in patient care outside of the psychiatric setting. Psychiatrists spend more time taking care of patients with more serious and complex illnesses, including people who aren’t responding to standard treatment.

It’s not that hard to make the diagnosis of a depressive episode, but you do need some time. And so, ways of streamlining, or ways of improving efficiency have evolved to make primary care providers more efficient. A really useful scale called the PHQ-9 [Patient Health Questionnaire, depression module] has the 9 common signs and symptoms of depression with a little 3-item rating scale for each one. It enables you to quickly explore the presence or absence of each of the potential symptoms. And so, you can at least weigh the syndrome and determine if the cardinal symptoms are there, often with the patient’s help using the checklist even before they see you.

Now, it’s not foolproof. Sometimes there will be mistakes, and the person may have another condition. You may miss a complicating condition like a substance abuse disorder, for which withdrawal from the substance is actually causing the depressive symptoms. But, it’s a good starting place. With the average follow-up visit for primary care somewhere south of 10 minutes, having this checklist repeated at each visit gives you a way, again, of weighing how heavy the syndrome is and whether the patient’s making progress with treatment.

Depression is a condition that exists within a social matrix. And so, it not only affects the sufferer, but it also affects their family. It’s certainly valuable to have the input of family in terms of whether this illness is causing a problem, even whether it’s an illness or not. Is this an extreme example of normal grief, or has it gone beyond that? So a family member’s input and observations can be helpful. This is particularly helpful when the differential diagnosis is bipolar disorder or recurrent depression. In bipolar disorder, patients often see the hypomanias, sometimes even the manias, as their best self and not a sign of illness. Whereas the family members appreciate this is different in magnitude and in level of impairment or dysfunction from the patient’s best self.

Transcript edited for clarity.