You may have heard of a new study that concluded that people diagnosed with adult ADHD were more likely to end up with dementia, especially if they choose not to treat it with medications. The headlines in the popular press were scary: “Adult ADHD may take a toll on the brain,” and so forth. Worse, some health sites have already embedded this possibly untrue information in articles. But don’t panic because there are good reasons to question the research.
The study claimed that having a diagnosis of adult ADHD and not using medicines like Ritalin more than doubled the risk of dementia (increased it by 277% which is nearly three-fold). It also found that those people in the study with adult ADHD that took stimulant drugs did not get dementia. Should you rush to your doctor to be “checked” for ADHD and beg for stimulants just in case? Probably not. These shocking numbers are relative to a very small base number. Jump to “Stunning Statistics” later in this article if you can’t wait for more info on that.
Also, it’s important to note that childhood ADHD is considered by some to be a different condition from adult ADHD, so do not make any medication decisions for your child’s ADHD management based on this study.
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About The Study
There were about 110,000 people in the study, 51% women/49% men and all living in Israel.
It was an observational study, which means the study consisted of researchers reviewing people’s health records. Observational studies can be good indicators of trends and might suggest a link between a drug and an outcome, but that kind of study can’t show that one caused (or prevented) the other. The best way to show causation is with a gold standard study: double-blind, placebo-controlled trial. In that kind of study, patients are divided randomly into either a drug group or a placebo group so the effect can be measured. Neither the patients nor the doctors know who gets the placebo and who gets the drug.
Unfortunately, several health outlets have reported the results as if the conclusions are undeniable, encyclopedia-ready facts, which they aren’t.
All studies have limitations, and I’m going to share with you the limitations of this study and explain how public media have not done their job in questioning the conclusions. In his blog, Fact Checking Psychiatry, Chuck Ruby, PhD, supplied the following analysis of the study. Ruby has been a practicing psychologist for 20 years and is the executive director of the International Society for Ethical Psychology and Psychiatry.
The study does NOT show that if you have adult ADHD you will get dementia. The study found a correlation between the two. That means some people who have ADHD and don’t use ADHD drugs also end up with dementia. But the study cannot prove that undrug-treated ADHD causes dementia or is even linked in any way. The study didn’t even try to prove that, they simply found an overlap and reported it. This is a bit like finding out that the annual amount of money that U.S. households spend on pork correlates very closely with the stock price of Lululemon. Which, while the correlation exists, clearly means absolutely nothing.
You might wonder then, “but why don’t the adults who are diagnosed with ADHD and take stimulants (like Ritalin) also have a higher level of dementia?”
We don’t know, because this study cannot measure causation. On a guess, stimulants sharpen mental clarity for everyone. After two or three cups of coffee, I can compose a blog much faster than I can at 10 p.m. when the caffeine is gone. So the stimulant could be hiding the dementia, or it might not.
Stunning Statistics
But then, you ask, “ADHD adults are nearly three times as likely to get dementia! That’s a huge number. That can’t be a blip.”
It does look like a large number, but relative risk is a distortion of absolute risk, a fun house mirror so-to-speak. The reported 277% increase is a relative risk, not an absolute number. Remember, 7% of the people in the study who did not get diagnosed with ADHD did get diagnosed with dementia. The number of adults who got diagnosed with ADHD in the study who also got dementia was 13%. That’s about a 6% increase in people who may get dementia. That’s not nothing, but you can see it’s a lot smaller than a “nearly three times increase” sounds.
109,208 people in the trial
7,726 were diagnosed with dementia during the study, 7%
730 were diagnosed with ADHD during the study, .07%
96 were diagnosed with adult ADHD during the study, 13%
That’s 96 people out of 109,208, a vanishingly small number. Let’s say those 730 people did not get adult ADHD, then on average 7% or 52 of them would have gotten dementia anyway. Your risk is being in those last 44 people (out of 110k) who ended up with both ADHD and dementia. That’s a small number on which to base significant medical decisions.
Diagnosis Error
Here’s another way a study can go wrong, diagnostic error. The symptoms of ADHD and dementia are very similar. In a well-run study the same doctor or group of doctors would either make or review all the diagnoses ensuring the same criteria was used with each patient. That was not possible in the observational study.
Here’s a list of symptoms that Ruby supplied in his article on the International Society for Ethical Psychology and Psychiatry.
Dementia
- Trouble with planning and organizing
- Agitation and inappropriate behavior
- Confusion and disorientation or trouble performing complex tasks
- Personality changes
- Anxiety
ADHD
- Disorganization and problems prioritizing; poor planning
- Hot temper and impulsiveness, low frustration tolerance
- Problems focusing on task and problems following through and completing tasks
- Frequent mood swings
- Excessive activity or restlessness
Other medical organizations have other lists. Therefore, the same person with the same symptoms might be diagnosed with dementia by one doctor and ADHD by another and without either doctor being wrong.
So when you see alarming headlines on studies, consider who is writing the story (a scientist or a reporter?), who paid for the study, who was interviewed for the story (an independent scientist or health expert or the author of the study or no one?) and how “clickable” that headline is. Ideally, the journalist would speak to the author of the study along with at least one (if not more) experts who were not involved in the study for a hopefully-unbiased perspective on the findings.
Science and medicine are made up of building blocks of information. Some studies are done just to see if a topic deserves to be studied more carefully. This study suggests that one might want to create a double-blind, placebo-controlled research study to try to discover a causal link between adult ADHD and dementia. But even if that study is done and shows a probable link (which would be very surprising), don’t assume that study is right.
Medical science is constantly evolving, with researchers learning from and building on previous work. Someday soon scientists might go on to do cellular and molecular studies and better understand the causes for ADHD and dementia. In the meantime, when you get any diagnosis, ask questions, be sure you are comfortable that the diagnosis is right (listen to your body), consider all your options from doing nothing to meds including: changing your diet, using brain games, add supplements and keep an eye on research for more ideas.
