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ADHD is far more prevalent among persons with AUD (roughly 20 percent) than it is in the general population. The most accurate way of identifying ADHD is through structured clinical interviews. Given that this is not feasible in routine clinical settings, ADHD self-report scales offer a less reliable but much less resource-intensive alternative. Could the latter be calibrated in a way that would yield diagnoses that better correspond with the former?

A German team compared the outcomes of both methods on 404 adults undergoing residential treatment for AUD. All were abstinent while undergoing evaluations. First, to obtain reliable ADHD diagnoses, each underwent the Diagnostic Interview for ADHD in Adults, DIVA. If DIVA indicated probable ADHD, two expert clinicians conducted successive follow-up interviews. ADHD was only diagnosed when both experts concurred with the DIVA outcome.

Participants were then asked to use two adult ADHD self-report scales, the six-item Adult ADHD Self Report Scale v1.1 (ASRS) and the 30-item Conners’ Adult ADHD Rating Scale (CAARS-S-SR). The outcomes were then compared with the expert interview diagnoses.

Using established cut-off values for the ASRS, less than two-thirds of patients known to have ADHD were scored as having ADHD by the test. In other words, there was a very high rate of false negatives. Lowering the cut-off to a sum score ≥ 11 resulted in a correct diagnosis of more than seven out of eight. But the rate of false positives soared to almost two in five.  Similarly, the CAARS-S-SR had its greatest sensitivity (ability to accurately identify those with ADHD) at the lowest threshold of ≥ 60, but at a similarly high cost in false positives (more than a third).

The authors found it was impossible to come anywhere near the precision of the expert clinical interviews. Nevertheless, they judged the best compromise to be to use the lowest thresholds on both tests and then require positive determinations from both. That led to successfully diagnosing more than three out of four individuals known to have ADHD, with a false positive rate of just over one in five.

Using this combination of the two self-reporting questionnaires with lower thresholds, they suggest, could substantially reduce the under-diagnosis of ADHD in alcohol-dependent patients.

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The ENIGMA-ADHD Working Group published their second large study on the brains of people with ADHD in the American Journal of Psychiatry this month. In this second study, the focus was on the cerebral cortex, which is the outer layer of the brain.

ADHD symptoms include inattention and/or hyperactivity and acting impulsively. The disorder affects more than one in 20 (5.3%) children, and two-thirds of those diagnosed continue to experience symptoms as adults.

In this study, researchers found subtle differences in the brain’s outer layer - the cortex - when they combined brain imaging data on almost 4,000 participants from 37 research groups worldwide. The differences were only significant for children and did not hold for adolescents or adults. The childhood effects were most prominent and widespread for the surface area of the cortex. More focal changes were found in the thickness of the cortex. All differences were subtle and detected only at a group level, and thus these brain images cannot be used to diagnose ADHD or guide its treatment.

These subtle differences in the brain’s cortex were not limited to people with the clinical diagnosis of ADHD: they were also present - in a less marked form - in youth with some ADHD symptoms. This second finding results from a collaboration between the ENIGMA-ADHD Working Group and the Generation-R study from Rotterdam, which has brain images on 2700 children aged 9-11 years from the general population. The researchers found more symptoms of inattention to be associated with a decrease in cortical surface area. Furthermore, siblings of those with ADHD showed changes to their cortical surface area that resembled their affected sibling. This suggests that familial factors such as genetics or shared environment may play a role in brain cortical characteristics.

This is the largest study to date to look at the cortex of people with ADHD. It included 2246 people with a diagnosis of ADHD and 1713 people without, aged between four and 63 years old. This is the second study published by the ENIGMA-ADHD Working Group; the first examined structures that are deep in the brain. The ADHD Working Group is one of over 50 working groups of the ENIGMA Consortium, in which international researchers pull together to understand the brain alterations associated with different disorders and the role of genetic and environmental factors in those alterations.

The authors say the findings could help improve understanding of the disorder. ‘We identify cortical differences that are consistently associated with ADHD by combining data from many different research groups internationally. We find that the differences extend beyond narrowly-defined clinical diagnoses and are seen, in a less marked manner, in those with some ADHD symptoms and in unaffected siblings of people with ADHD. This finding supports the idea that the symptoms underlying ADHD may be a continuous trait in the population, which has already been reported by other behavioral and genetic studies.’. In the future, the ADHD Working Group hopes to look at additional key features in the brain- such as the structural connections between brain areas – and to increase the representation of adults affected by ADHD, in whom limited research has been performed to date. 

See: https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2019.18091033

Sleep disorders are one of the most commonly self-reported comorbidities of adults with ADHD, affecting 50 to 70 percent of them. A team of British researchers set out to see whether this association could be further confirmed with objective sleep measures, using cognitive function tests and electroencephalography (EEG).

Measured as theta/beta ratio, EEG slowing is a widely used indicator in ADHD research. While it occurs normally in non-ADHD adults at the conclusion of a day, during the day it signals excessive sleepiness, whether from obstructive sleep apnea or neurodegenerative and neurodevelopmental disorders. Coffee reverses EEG slowing, as do ADHD stimulant medications.

Study participants were either on stable treatment with ADHD medication (stimulant or non-stimulant medication) or on no medication. Participants had to refrain from taking any stimulant medications for at least 48 hours prior to taking the tests. Persons with IQ below 80 or with recurrent depression or undergoing a depressive episode were excluded.

The team administered a cognitive function test, The Sustained Attention to Response Task (SART). Observers rated on-task sleepiness using videos from the cognitive testing sessions. They wired participants for EEG monitoring.

Observer-rated sleepiness was found to be moderately higher in the ADHD group than in controls. Although sleep quality was slightly lower in the sleepy group than in the ADHD group, and symptom severity slightly greater in the ADHD group than the sleepy group, neither difference was statistically significant, indicating extensive overlap.

Omission errors in the SART were strongly correlated with sleepiness level, and the strength of this correlation was independent of ADHD symptom severity. EEG slowing in all regions of the brain was more than 50 percent higher in the ADHD group than in the control group and was highest in the frontal cortex.

Treating the sleepy group as a third group, EEG slowing was highest for the ADHD group, followed closely by the sleepy group, and more distantly by the neurotypical group. The gaps between the ADHD and sleepy groups on the one hand, and the neurotypical group on the other, were both large and statistically significant, whereas the gap between the ADHD and sleepy groups was not. EEG slowing was both a significant predictor of ADHD and of ADHD symptom severity.

The authors concluded, These findings indicate that the cognitive performance deficits routinely attributed to ADHD are largely due to on-task sleepiness and not exclusively due to ADHD symptom severity.  we would like to propose a simple working hypothesis that daytime sleepiness plays a major role in cognitive functioning of adults with ADHD. As adults with ADHD are more severely sleep deprived compared to neurotypical control subjects and are more vulnerable to sleep deprivation, in various neurocognitive tasks they should manifest larger sleepiness-related reductions in cognitive performance. One clear testable prediction of the working hypothesis would be that carefully controlling for sleepiness, time of day, and/or individual circadian rhythms would result in a substantial reduction in the neurocognitive deficits in replications of classic ADHD studies.