It’s odd what upsets some people. Take E. Fuller Torrey and Elizabeth Sinclair’s recent take on a change in the way a single number — the 12-month prevalence rate of schizophrenia — is displayed on the National Institute of Mental Health’s (NIMH) website.
This esoteric number has little impact in most people’s lives. If you live with schizophrenia or know someone who does, they most likely don’t give a hoot about it. Like most people, they probably don’t even know what it means.
But these two authors do care, suggesting the number was reduced due to a hypothesized renewed focus on accountability of the NIMH. In their blazing, fear-mongering headline, they boldly claim that “the National Institute of Mental Health Made Two Million People with Schizophrenia Disappear.”
So what’s the truth about the numbers with schizophrenia, and what is “fake news?” Let’s find out…
Prevalence rates are always estimates — we don’t know with any certainty how many people in a given population actually have a given disease or condition. Researchers generally conduct surveys to find out, most often done by telephone, but sometimes by in-person visits or through analyzing government data.
Prevalence rates give researchers a good idea of how prevalent a given disease or condition exists in a country’s population. This can help guide government policy for treatment, whether it be a vaccine for a new strain of bird flu, or directing more money to a condition that seems to be increasing in rate.
Prevalence rates are fairly stable for most conditions in most populations. Despite an array of modern treatments, mental disorders rarely see a marked decline or increase in their rates from decade to decade.
Two Types of Prevalence
For this discussion, it’s important to note two types of prevalence researchers talk about — 12-month prevalence and lifetime prevalence.
For 12-month prevalence, a researcher is estimating how many people in a given population have the condition, including those who had it at the start of the period as well as those newly diagnosed. For lifetime prevalence, a researcher is looking at the percentage of the population that is diagnosed with the condition at some point in their life.
If you had a bout of panic attacks in your 20s and saw a therapist to treat them successfully, and no longer experience such attacks now that you’re in your 30s, you would be counted in the lifetime prevalence number, but not the 12-month number. 1
Schizophrenia’s Prevalence Rates
Torrey, founder of the Treatment Advocacy Center (TAC), and Sinclair cry foul to the NIMH daring to update their website to reflect the most current data about schizophrenia prevalence rates:
Until November 2017, NIMH had claimed that the one-year prevalence of schizophrenia in adults in the US was 1.1%. […]
Inexplicably, in November 2017, NIMH changed its website and declared that the one-year prevalence of schizophrenia is now 0.3%, or 3 cases in 1,000 adults.
It’s hardly inexplicable. New research means new data. You update your website to reflect that new data. What exactly is so inexplicable about that?
What’s more inexplicable is Torrey and TAC using a magician’s metaphor and a fear-mongering headline to suggest that the federal government is somehow making actual people living with mental illness disappear. Data are not people — especially when you use that data to scare others into believing something clandestine is happening within the NIMH.
In 1994, the American Psychiatric Association published the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), and stated, “[…] the lifetime prevalence of Schizophrenia is usually estimated to be between 0.5% and 1%.” In the revised edition of this manual released in 2013, they stated that the lifetime prevalence of schizophrenia “appears to be approximately 0.3% – 0.7%” — a seeming decline in their estimates.
It’s hard to say whether the decline was real or just due to more research and data becoming available in the nearly 20 year period publication of these two reference manuals. I’d argue the latter, since there was indeed a fair number of new prevalence studies published throughout the world about schizophrenia during that period.
The Current Final Word on Schizophrenia Prevalence Rates
The most reasonable explanation for why the NIMH decided to update its website with more up-to-date, accurate numbers is due to a comprehensive review of schizophrenia prevalence rates published in 2015 (Simeone et al., 2015).2 These researchers combed all published data in the world on both types of prevalence rates related to schizophrenia.
The researchers found 65 studies in all to look at. Thirty-one (48 percent) were from Europe and 35 (54 percent) were conducted in samples of greater than 50,000 people. These are pretty robust numbers to be examining.
What did they find? “Among 21 studies reporting 12-month prevalence, the median estimate was 0.33 percent with a [range of between] 0.26 – 0.51 percent. The median estimate of lifetime prevalence among 29 studies was 0.48 percent [with a range of between] 0.34 – 0.85 percent.”
Now unless we want to claim that the U.S. is somehow a wildly odd outlier here — where the 12-month prevalence rates of schizophrenia are more than triple the median estimate (and double the highest estimate!), the NIMH’s new numbers make perfect sense. They are backed up science and hard data — the enemy of people who like to spread fake news around for political purposes.
Like it or not, science tells us that the 12-month prevalence rate of schizophrenia is in the 0.26 to 0.51 range, with a median of 0.33 percent. The NIMH is correct. The Treatment Advocacy Center is not, and instead seems to prefer to rely on decades-old, outdated data.
And that’s the point. Science is here to help us keep informed about the world around us. If we bury our heads in the sand and loudly proclaim that the number must be wrong because it’s always been some other number, we’re choosing to remain ignorant and not informed by the latest and most accurate scientific data.
Torrey and Sinclair seem to be arguing the number not from a scientific point of view, but rather from a political one.3 And that’s a shame, because data doesn’t give one whit about politics.
And neither should those who are seeking to keep others informed about important mental health issues.
American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Arlington, VA.
American Psychiatric Association. (1994). Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Arlington, VA.
Simeone, Jason C.; Ward, Alexandra J.; Rotella, Philip; Collins, Jenna; Windisch, Ricarda. (2015). An evaluation of variation in published estimates of schizophrenia prevalence from 1990-2013: A systematic literature review. BMC Psychiatry, 15.
- Chronic conditions where maintenance treatment — rather than a cure — is the norm can sometimes exhibit similar 12-month and lifetime prevalence numbers (within 1 percent of one another). Schizophrenia is arguably in this category, because most people who have schizophrenia typically have it for much of their adult life. [↩]
- Why it took the NIMH nearly two years to update their website since this data was published is another question. [↩]
- I can agree, however, with their conclusion that not enough money is spent to study prevalence rates — for most mental disorders. As Simeone et al. (2015) pointed out three years ago, “Several large, heavily populated countries (such as, Brazil, France, Germany, Japan, and Russia) had either one or no published studies on the prevalence of schizophrenia among general populations, while estimates from many other countries were >10 years old and in need of updating. In fact, the only schizophrenia prevalence estimates from Central or South America were the country-specific estimates presented in the 2003 WHS study.” [↩]