This study tested mindfulness-based cognitive therapy (MBCT) in adult outpatients with ADHD. They were aged 18 to 65 and recruited at Radboud University Nijmegen Medical Centre. In all, 61 adults were randomized to MBCT or a wait-list, and 44 were included in the final analysis. Of the 50 who stayed in the study, 31 took medication, which was kept stable throughout. A psychiatrist specializing in ADHD led 12 weekly 3-hour sessions, with guided home practice.
Brain signals were recorded during a task that asked people to respond on some trials and hold back on others. After MBCT, one brain response linked to holding back grew larger, while the wait-list group showed no such change. The authors say this gain was found only with MBCT. A signal tied to noticing one's own errors rose in both groups, so it was not specific to MBCT. Two other signals did not clearly change.
People in the MBCT group reported fewer inattention and hyperactivity symptoms, less distress and better mindfulness skills. The wait-list group did not. Within the MBCT group, people whose symptoms dropped more tended to show larger increases in certain brain responses. The MBCT group also made fewer mistakes on the task, but this change did not clearly differ between groups.
The authors name three limits. There was no active comparison group. Over half the patients took medication. Symptoms were self-reported, with no objective measure.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Schoenberg, 2014: change in self-reported ADHD symptoms, MBCT compared with wait-list, F(1, 38) = 9.248, p = .004.
- Schoenberg, 2014: drop in self-reported inattention within the MBCT group, t(22) = 4.891, p < .0001.
- Schoenberg, 2014: drop in the overall ADHD symptom score within the MBCT group, t(22) = 4.239, p < .0001.
- Schoenberg, 2014: change in distress and daily functioning, MBCT compared with wait-list, F(1, 38) = 4.924, p = .033.
- Schoenberg, 2014: change in mindfulness skills, MBCT compared with wait-list, F(1, 38) = 22.845, p < .0001.
- Schoenberg, 2014: growth in the holding-back brain response at the Pz scalp site in the MBCT group, t(23) = −2.502, p = .02.
- Schoenberg, 2014: the same brain response in the wait-list group, p = .40.
- Schoenberg, 2014: growth in the error-noticing brain response at the FCz scalp site in the MBCT group, t(23) = −2.613, p = .02.
- Schoenberg, 2014: growth in the error-noticing brain response at the Fz scalp site in the wait-list group, t(19) = −2.809, p = .01.
- Schoenberg, 2014: link between a drop in hyperactivity symptoms and growth in the error-noticing response at Fz, MBCT group only, r(23) = −.456, p = .03.
- Schoenberg, 2014: link between a drop in inattention and growth in the holding-back response at Cz, MBCT group only, r(23) = −.476, p = .02.
- Schoenberg, 2014: average task mistakes before and after in the MBCT group, 25.3 (17) to 19.8 (15), p = .001.
- Schoenberg, 2014: average task mistakes before and after in the wait-list group, 26.2 (17) to 25.6 (15), p = .83. What the terms mean:
- t a test of whether a change within one group is bigger than chance would produce. A minus sign shows the direction of the change, not its size.
- F a test of whether two groups changed differently over time.
- p the chance of seeing a result this strong if there were no real effect. Smaller means less likely to be down to chance.
- r how closely two things move together, from 0 (not at all) to 1 (perfectly). Here a minus sign means symptoms fell as the brain response grew.
Source: Schoenberg P, Hepark S, Kan C, et al.. Effects of mindfulness-based cognitive therapy on neurophysiological correlates of performance monitoring in adult attention-deficit/hyperactivity disorder. Clinical Neurophysiology (2014). doi:10.1016/j.clinph.2013.11.031