Here's a neat little study that examined whether it was possible to distinguish between college students who had been diagnosed with ADHD, students who were asked to feign ADHD, and a group of control subjects who were asked to respond honestly. The authors used a bunch of different self-report measures and neuropsychological tests that are commonly used for a diagnosis of ADHD. They also administered several measures of feigning or what they called Symptom Validity Tests (SVTs).
The study was on the smaller side (29 ADHD, 30 feigners, and 14 controls), but the authors were nice enough to report effect sizes instead of relying on p-values alone. The controls were asked to respond as they normally would. Most of the subjects with previously diagnosed ADHD (usually determined by some fairly extensive evaluation at some point of time in their past) were on some sort of medication as well, and came in for the study after a 12-hour washout period. They were also asked to respond normally. Last was the group of feigners, who were given some information about ADHD compiled from a few hits from Google for them in advance. This group was asked to fake symptoms of ADHD throughout the experiment, but also cautioned to remember that they should perform at least as well as someone who was in university. They were also told that they would be given an incentive of $45 if they managed to fool the examiner.
The self-report measures did not distinguish between those diagnosed with ADHD and the feigners at all, though the controls scored lower than both these groups. This suggested that those with ADHD and those asked to feign were reporting similar levels of ADHD symptoms.
The neuropsychological tests (which included a test of reading skills, the Stroop color and word test, a test of recalling a list of words, and a task called the CPT where you press a spacebar or some such key to any letter except an X when they appear on the screen) proved more interesting. Generally speaking, the feigners responded in such a way that they showed the greatest level of impairment on most tests compared to both the controls and the ADHD-ers -- in other words, the feigners tended to overdo it. The latter two groups, however, generally did not differ from each other statistically, though the ADHD-ers did numerically worse than the controls. Basically, the tests were picking up moderately well on feigners, but not those with ADHD.
On an aside, having administered quite a few of these neuropsych tests to patients myself, I can personally attest to the fact that some of these tests are mind-numbingly boring and are as much an assessment of ADHD for the examiner as they are for the subject.
Anyway, back on topic - last were the SVTs. These pretty much followed the same pattern as the neuropsych tests. Feigners did statistically worse than controls and ADHD-ers, though the latter two groups didn't differ from each other. Interestingly, however, these SVTs were generally not very sensitive to feigning (i.e., identifying people who were feigning as feigning) though their specifity to ADHD was pretty good (identifying people without ADHD as not having ADHD).
Anyway, to sum it all up, pretty much none of the measures used in this study did a good job of differentiating those with and without ADHD, apart from the self-report ones and those are pretty easy to fake anyways. The neuropsych tests did an OK job on picking up on the feigners or those asked to fake ADHD since they did overdo it on quite a few of the tests, but since these are already general measures for these (e.g., some of the SVTs used in the study), it doesn't seem very useful to use ADHD-specific measures like the CPT for this purpose (which seemed to have functioned pretty crappily in this study anyway).
Now, this study did use a college population, so presumably, the really impaired folks with ADHD were not a part of the study. However, as the authors note, since a lot of assessments are done on college kids (and younger kids in school), if the neuropsych tests don't pick up on these problems in these less impaired populations, what is the point of administering these tests to detect ADHD in the first place?
More importantly, an issue that the authors skirt around in the discussion is that there seems to be no sign really that there is anything specific to the ADHD diagnosis in their study. However, that is a pretty bold statement to make, and their study is on the smaller side. I probably wouldn't have made it either if I were writing up the study. But, results like these make you wonder what it means to have ADHD, and whether it deserves a diagnostic status as a disorder in its own right. Things like difficulties with attention and impulsivity are nonspecific symptoms that are implicated in a whole lot of other disorders like depression, substance problems, schizophrenia, borderline personality disorder, and so on. It's kinda like trying to diagnose which medical disorder somone has from knowing that they have fever. Without knowing other symptoms, one would be hard pressed to figure out whether the fever is part of a flu, meningitis, hepatitis, or leukemia, and how to treat it, no?
Sollman, M., Ranseen, J., & Berry, D. (2010). Detection of feigned ADHD in college students. Psychological Assessment, 22 (2), 325-335 DOI: 10.1037/a0018857
