Mind Wandering Predicts ADHD Impairment Beyond Symptom Counts

The items

“I find it hard to switch my thoughts off.” “I have two or more different thoughts going on at the same time.” “My thoughts are ’on the go’ all the time.” “I find myself flitting back and forth between different thoughts.” Fifteen statements of this kind make up the Mind Excessively Wandering Scale, each answered on four points running from “not at all or rarely” to “nearly all of the time or constantly.”

Every item asks about the form of a person’s thinking, an experience only the person having it can report. The diagnostic criteria for ADHD describe behaviour observable from outside; these items describe a mental state from within.

Philip Asherson, Caroline Skirrow and Peter Reid at King’s College London drew the list out of what adults attending an ADHD clinic said when asked to describe the flow of their own thoughts. Florence Mowlem and colleagues reported the first validation of the finished scale in the Journal of Attention Disorders in 2016. Mind wandering is the term for attention moving off the task at hand and onto unrelated internal thoughts, which everybody does.

Two London samples were used, all adults aged 18 to 65: first, 41 men with ADHD selected for the absence of any other psychiatric condition, alongside 47 male controls; then 81 adults with ADHD, 37 of them women, alongside 30 controls.

Principal components analysis, which examines how answers cluster, found a single underlying factor accounting for 69 percent of the variation in the first sample and 63 percent in the second. Three items behaved less well, the ones about lying awake, distracting oneself with music, and using alcohol to slow the thoughts down; each asks how a person copes, and the authors recommend dropping them.

Adults with ADHD and controls separated cleanly on the totals: 25.0 against 4.8 in the first sample and 27.7 against 7.2 in the second, on a range of 0 to 45. A threshold score of 15 identified 90 percent of ADHD cases in the larger sample and correctly cleared 90 percent of controls, matching the established symptom questionnaires used alongside it.

Scores correlated with the Barkley and Conners ADHD questionnaires between .69 and .81 across symptom domains and samples, and correlated most strongly with functional impairment. Whether the scale added anything beyond those instruments was the harder test. In the larger sample, inattention and hyperactivity together accounted for 71 percent of the variation in impairment; adding mind wandering raised that to 79 percent, and mind wandering became the strongest single predictor in the model, ahead of inattention. In the smaller sample the gain was 2.4 percentage points, small but statistically reliable. Their descriptions of their own thinking told the researchers something the symptom counts had missed.

What this means for you and your child

The scale was built for adults, validated on adults, and its authors state plainly that whether children and young adolescents can conceptualise mind wandering and report on it reliably remains to be investigated. There is no test here for a parent to administer.

What the two studies do establish is that one particular description, thoughts that will not switch off, two lines running at once, thinking that flits between subjects, is frequent enough among adults with ADHD to separate them from adults without it at rates matching the standard instruments. That account of the inside of a day is a documented feature of the condition, with a name and a published measure attached to it.

The measure also behaved consistently over time. Scores taken from the same people about six months apart in one study, and about nine in the other, correlated at .63 and .84, so what the items pick up looks like a steady characteristic of a person. Where scores did shift, they shifted alongside changes in inattention and changes in impairment.

The authors decline to recommend the scale for routine identification of ADHD, and their reason is exact. Depressive rumination and anxious worry are also thoughts that will not stop, and the scale has not yet been examined in those conditions, so a high score cannot indicate which source it came from. High scores can support a diagnosis already under consideration.

Both the mind wandering scores and the impairment scores came from the same people describing themselves, and the design was observational, so the results show that the two travel together without establishing that one produces the other. Sixteen men who began methylphenidate between assessments scored lower afterwards, falling from 23.4 to 17.3, though nobody was randomised and no placebo group existed, which leaves the drug unproven as the cause of the change.

The words these adults used to describe an ordinary hour are plain enough to be said aloud in a consulting room: ceaseless, flitting, two thoughts at once, difficult to switch off. A clinician who hears them is being given information that no symptom checklist requests. If that is the account your child has been trying to give you, those are the words to bring into the room.