New studies suggest that the larger the amount of grey matter, that is essentially, the larger your brain, the more likely you have to have difficulty maintaining focus.

According to Dr. Ryota Kanai and his fellow cognitive neuroscientists at University College London, revealed that individuals who are distracted easily from their current tasks may just have ‘too much brain’.

Specifically, the team found that larger than average amounts of grey matter in key areas of the brain in individuals with poor attention spans.

Although the study did not specifically test for ADHD, they did investigate and compare the degree of difficulty in distracting the subjects of their study. To assess their distractibility, the team quizzed them about how frequently they do not notice road signs, or go into a supermarket and become sidetracked to the point that they forget what they came in to buy. The most distractible the individual, the higher the score they received.

Once the subjects were assessed and scored for their relative degrees of distractibility, their brains were then imaged with a structural MRI scanner. The biggest discrepancy between those subjects with the highest score – individuals who are easily distracted – and those with the lowest score was the amount of grey matter in the left superior parietal lobe (SPL) region of the brain. What they discovered was that the more easily distracted an individual was, the higher the volume of grey matter in their left SPL.

Brain Dampening

To determine whether or not the neurological activity taking place in the left SPL has a role in distractibility, Dr. Kanai and his colleagues utilized transcranial magnetic stimulation (TMS) in order to dampen the brain activity directly underneath it for approximately 30 minutes.

Electrodes, ADHD, ADD

A demonstration of electrodes placed on the head of a patient with ADHD.

First, the scientists took 15 subjects and asked them to perform a task both with and without a distraction – the difference between the time taken to complete each task being used as a measure of distractibility.

When these same individuals repeated this exercise following the application of TMS to the left SPL, the time it took to complete each task increased by approximately 25%. This suggest that this section of the brain, the left SPL, is directly involved in the top down control of attention, according to Dr. Kanai.

Immature Brain

When combined, the two experiments together allowed the researchers to infer that the region of the brain in question, the left SPL, works to overcome distraction, and those who happen to have a larger left SPL being more distractible.

While this is extremely interesting and potentially enlightening with respect to ADHD research, exactly why the volume of grey matter works in this fashion is unknown. Some researchers suggest that it may be attributable to the fact that as we mature, the neurons in the brain’s grey matter is thinned in order to work in a more efficient manner.

Dr. Kanai himself speculates that:

The theory that neurons in the brain’s grey matter is reduced would fit with the observation that children are more easily distracted than adults. The larger volume of grey matter in the brain may also indicate a less mature brain, a reflection of a mild developmental dysfunction perhaps.

While this may appear to be bad news, having identified that the left SPL plays a role in distraction, Kanai’s team has started to investigation ways to ameliorate concentration and focus by stimulating the left SPL employing a procedure known as transcranial direct current stimulation (TDCS). This technique places electrodes on and around the head to supply an imperceptible electrical current to the targeted area.

The aim of these techniques and tests is to modulate attention, and Dr. Kanai says that some signs indicate that this is a very real possibility. If this is indeed confirmed, TDCS might prove to be a valuable asset in treating ADHD without drugs.


  • Stephanie
    July 27, 2013 Reply

    That’s all very interesting. I’m not easily distracted but will lose my focus on any given thing If I don’t find it interesting. Usually that’s work! Which might be play into a previous post that connected lower pay and being left handed (and ADD.)

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