It has been over 15 years since large-scale data has been collected on depression and other illnesses in the United States, though smaller studies suggest rates of depression have been on the rise. In addition, existing data is based on DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) criteria for diagnosis, and psychiatry is now using the DSM 5. The DSM 5, though the subject of some controversy, has been updated to reflect better understanding of and research on various psychiatric conditions, with the intention of allowing for more accurate diagnosis and therefore a better basis for treatment planning. There have been a lot of changes in understanding since the DSM IV was first published in 1994, reflected in the 2013 edition of the DSM 5.
For Major Depressive Disorder (MDD), the DSM 5 now describes new “specifiers” for depression, including episodes associated with anxious distress, episodes associated with manic or hypomanic features which do not meet criteria for Bipolar Disorder, and notably now allows severe bereavement reactions to be considered depressive episodes (one of the controversial areas). Until the 2012-2013 National Epidemological Survey on Alcohol and Related Conditions (NESARC-III), these changes to the DSM criteria for depression had not been looked at in a large population-based sample, but only in smaller studies.
The NESARC-III involves surveying U.S. civilians in residential settings, using sampling methods to ensure an accurate representation of the broader population. For instance, selection was weighted to account for difference in how different groups (e.g. ethnic groups) historically respond to surveys. From the total population of non-institutionalized adults in the U.S., based on U.S. Census records, a sample of 36,309 people were identified, with a 60 percent response rate. Data was collected over a year from Spring of 2012 to Summer of 2013, and analyzed in 2016-17. Respondents were surveyed by interviewers trained for quality control, and data collected was verified by random checks following the interview. Various standard measures were included to identify diagnostic markers for alcohol and substance use disorders, depression and other psychiatric conditions, and level of impairment.
What did we learn?
Overall, the NESARC-III survey determined that the prevalence of depression in a 12 month period was 10.4 percent and over the course of a lifetime 20.6 percent. Broken down by gender, prevalence of MDD for women was 13.4 percent and 26.1 percent, and for men 7.2 percent and 14.7 percent. In keeping with prior research, women are at greater risk of depression. In terms of ethnic groups, Whites and Native Americans were at greater risk than Hispanic, Black or Asian respondents. Younger adults were at greater risk for MDD than adults over the age of 65, and lower income was associated with greater risk. Function was significantly impaired compared to those without depression, and was worse with greater severity and among those with MDD within the past 30 days.
What other conditions where associated with MDD? It turns out that MDD increased the risk of having all other co-occurring conditions. For some conditions, such as generalized anxiety disorder, borderline personality disorder, and PTSD, the additional risk was close to double or more, while for other diagnoses the additional risk was smaller. Most depressive episodes lasted longer than 6 months, and during more severe episodes the majority (75 percent) experienced the anxiety and distress subtype, with a smaller percent (15) with hypomanic-manic symptoms. About 13 percent reported MDD following the death of a close loved one, and those episodes usually lasted less than 2 months.
What about MDD treatment? A little bit over 69 percent of people reported getting treatment, 53 percent with medication, 62.5 percent through professional therapy, and almost 15 percent via non-professional support including self-help, support groups, and online. About 10 percent reported having sought emergency services related to depression, and 10 percent reported being hospitalized. Treatment, in addition to missing over 30 percent of people with depression, was delayed by nearly 4 years from the average age of onset at 32 years old.
Over the course of a lifetime, people with depression reported frequent thoughts about death. When depression was at its most severe, nearly 35 percent of people reported thinking about their own death, over 45 percent wanted to die, and almost 40 percent thought about dying by suicide. Looking at MDD within the past year, nearly 30 percent of people reported thinking about their own death, over 30 percent wanted to die, and almost 30 percent thought about dying by suicide. Over the course of a lifetime, 13.6 percent reported suicide attempts, and in the last 12 months, nearly 5 percent did.
What does it mean?
Generally, these findings are consistent with past results, though treatment rates in this survey are 10 percent greater than in the prior NESARC survey in 2001-2. This is a positive trend, as more people are receiving care, but 30 percent of people with depression are not receiving treatment. In addition, more people are self-medicating, for example with marijuana, which has not been shown to be effective for depression and in fact typically worsens depression.
While more people are receiving care, perhaps as a result of greater public awareness, increasing screening and treatment in primary care settings, destigmatization from government and consumer group campaigns, and advertising (e.g. for medications and therapy), more people are also using marijuana when it may make things worse, perhaps as a result of legalization, lobbying and cannabis industry advertising.
Given the high proportion of the anxious and distressed MDD subtype, attention should be focused on treating these symptoms and screening for and addressing co-occurring issues, including improving coping mechanisms and treating substance-related and psychiatric conditions. Future research and treatment initiatives will be based on updated statistics from NESARC-III, and the next NESARC will check progress on the population level. We need to identify and help the 30 percent of people who are depressed, and untreated.