“outgrow” ADHD continue to manifest many of its symptoms.
Adults may score just under the cutoff on diagnostic checklists,
but they are likely to continue to have abnormal brain structure, as well as functional impairments in relationships and
THE CHANGING BRAIN.; Researchers once thought that
each human function was assigned to a specific part
of the brain, and that a part damaged by trauma or
disease permanently lost its function. Now, research has shown that the human brain changes
in response to stimulation; brains have neuroplas-ticity. The good news is that your brain retains this
ability to change from birth to old age. ADHD brains
that have deficits in one area will attempt to rewire themselves to accomplish a task.
There are activities that can increase the brain’s effectiveness. Meditation, for example, changes the brain in important
ways. Researchers worked with people who’d never meditated
before (ADHD was not accounted for as a variable), and put
one group through an eight-week mindfulness-based stress-reduction program. The primary difference was in the posterior cingulate, which is involved in mind wandering and self-awareness. Another notable change was in the left
hippocampus, which assists in learning, cognition, memory,
and emotional regulation. Subsequent studies applied this
research using ADHD participants, and similar changes were
The ADHD Brain: A Network of Its Own
Researchers at Harvard University studied ADHD and non-ADHD subjects as they responded to a challenging cognitive
task. While both groups had difficulty with the task, the ADHD
group failed to activate their anterior cingulate cortex, which
plays two significant roles in attentional processing: adjusting
the focus of a person’s attention (where and when) as well as
balancing the focus of attention (how much attention for how
long). ADHD participants engaged a different, less specialized
part of their brain when tackling the task.
WHAT THIS MEANS. ; This research highlights what individuals with attention deficit already know. It is difficult to know
what to do and when to do it. This is because of an apparent
lack of ability to engage the most effective part of their brain,
the anterior cingulate cortex.
The default mode network (DMN) represents the regions
of the brain that are active when no specific task is being performed—while daydreaming, say, an activity that is undervalued by researchers and society. In the past, this was called
the “resting state.” Once functional scans showed how active
the brain is at rest, the name was changed.
The DMN takes care of task-irrelevant mental processes,
hour after stimulant medications are taken. This is
why neuroscientists now say that stimulants normalize
dopamine function in the brains of people with ADHD.
Functional imaging gives information about activity in
specific areas of subjects’ brains before and during task performance. Functional magnetic resonance imaging
(fMRI) shows oxygen uptake in areas of high nerve
activity, and magnetoencephalography (MEG)
shows us nerve activity in detail. A promising variant of fMRI, called fMRI-DTI (for diffusion tensor
imaging), measures the connection between different regions of the brain. Crosstalk—the ability
of different regions of the brain to communicate with
each other—is vital to brain function, and it is significantly reduced in ADHD brains.
Many different techniques are used in brain imaging—
though not all provide valid or generalizable information—
and they give researchers useful glimpses into brain wiring
and structure. In order to understand ADHD better and to treat
it more effectively, we need to know the wiring of the brain
and how it operates.
The ADHD Brain: Structurally Different
Neuroimaging studies have revealed the structural differences
in the ADHD brain. Several studies have pointed to a smaller
prefrontal cortex and basal ganglia, and decreased volume of
the posterior inferior vermis of the cerebellum—all of which
play important roles in focus and attention.
WHAT THIS MEANS. ; ADHD is not a difference in behavioral
preference. Instead, ADHD appears to be partially attributed
to a difference in how the brain is structured. What may look
like behavioral choices—laziness, sloppiness, and forgetfulness—are likely due to differences in brain structure.
Researchers at Cambridge, England, and Oulu, Finland, followed 49 adolescents diagnosed with ADHD at age 16 and examined their brain structure and memory function in young
adulthood (between 20 to 24 years old), compared to a control
group of 34 young adults. The results showed that the group
diagnosed in adolescence had reduced brain volume as adults,
leading to poorer memory function, even if they no longer met
the diagnostic checklist criteria for ADHD. Researchers saw
reduced gray matter in a region deep within the brain known
as the caudate nucleus, the brain region that integrates information across different parts of the brain and supports cognitive functions, including memory.
Because the structural differences persist into adulthood
for most children with ADHD, the chance that a child will outgrow ADHD is not as great as we once thought. Sixty to 75
percent of adults who had ADHD in childhood continue to
meet diagnostic criteria in adulthood. Most of those who