ADHD is a genetic difference in brain function, in which the ADHD person’s brain is driven to focus on stimuli that it finds inherently interesting. This is different for each person: video games, sports, music, art, writing, science, or other things. He or she cannot command the brain to find a particular subject interesting if it really isn’t.
The unique way the ADHD brain focuses on and processes stimuli can be best understood by breaking it down into these characteristics:
Hyperfocusing
The ADHD brain doesn’t just focus on interesting stimuli: it hyperfocuses. It hyperfocuses, in fact, to the point that all other stimuli are blocked out. This means that the ADHD person doesn’t hear or see what’s around them unless it’s directly involved with the subject of their focused attention. Hyperfocusing can be a good and useful talent if centered on the right thing at the right time.
Distractibility
Conversely, if the ADHD person isn’t hyperfocused on something, their brain is searching for something interesting, and when they find it, their brain will hyperfocus on that. Thus, when an ADHD person is hyperfocused on the wrong thing at the wrong time, we say that they are distracted.
Overstimulation
When the ADHD person’s brain is constantly monitoring the environment for any possibly important stimuli, it can become easily overwhelmed. This can lead to overstimulation, frustration, and irritability, causing “snap attacks.”
Hyperactivity
Sometimes when the ADHD person’s brain is searching for something interesting to focus on, their brain urges the body to get up and move around to find something interesting. This is then called hyperactivity. Older children and adults usually don’t actually get up and move around, but their bodies want to, and they may feel or appear restless. Not everyone with ADHD has the hyperactive component.
Understimulation
Sometimes if the ADHD person can’t find anything interesting in the environment, then their mind may just shut down. We call this falling asleep. ADHD people can fall asleep in the most amazing places: on the back of a motorcycle, in the middle of a concert, and of course, in the front row of a boring college class.
Impulsivity
Because the ADHD brain is genetically predisposed to respond immediately and reflexively in situations, the ADHD person is often prone to saying or doing things without stopping and thinking first – which may end up causing them problems.
PET and SPECT scans: a look inside the ADHD brain
In the last decade, brain imaging techniques have led to a phenomenal increase in our understanding of the way the brain functions, including differences in the ADHD brain. In 1991, Alan Zametkin of the National Institute of Mental Health published the first research showing actual views of the differences in the way the ADHD brain works.
Since then, many other studies have looked at brain functioning in ADHD people. The most extensive library of SPECT (single photon emission computed tomography) scans of the brain is at the Amen Clinics in San Francisco and Los Angeles. Dr. Daniel Amen has done over 20,000 brain scans of people with ADHD and other problems of brain functioning.
Dr. Amen explains that individuals with ADD typically show normal brain activity when at rest. However, when they attempt to focus on a task, instead of an expected rise in activity within the prefrontal cortex, there is a decline, which contrasts with the response seen in individuals without ADD.
ADHD brain vs normal brain: Examples and scans
Image #1
This image is a series of functional brain scans, fMRI (functional Magnetic Resonance Imaging) or PET (Positron Emission Tomography) scans, showing brain activity in individuals with ADHD. The areas highlighted in orange and red indicate regions with altered activity. Differences in brain function compared to neurotypical individuals.
Key Observations from the Image:
- Increased and Decreased Activity:
- The highlighted regions suggest variations in brain activity, possibly indicating areas where there is hyperactivity or underactivity in ADHD brains.
- In particular, the prefrontal cortex, basal ganglia, and limbic system seem to show altered activation patterns.
- Prefrontal Cortex Dysfunction:
- The prefrontal cortex (frontal lobe area) is responsible for executive function, impulse control, and attention regulation.
- Research has shown that individuals with ADHD often have reduced activation in the prefrontal cortex when performing tasks that require focus and concentration.
- Basal Ganglia and Dopamine Regulation:
- The basal ganglia, which play a role in movement control and motivation, also appear to show abnormal activity.
- Many studies have linked ADHD to dopamine dysregulation, which affects reward processing and attention.
- Limbic System Involvement:
- The limbic system (which includes the amygdala and hippocampus) is involved in emotion regulation.
- Changes in this region might explain the emotional impulsivity and mood swings often observed in ADHD individuals.
Image #2
This scan visually supports research findings that ADHD brains exhibit decreased activity in the frontal lobe, sensory-motor cortex, and cerebellum. These differences in brain function help explain the challenges in attention, impulse control, and movement regulation that individuals with ADHD experience. The image reinforces the idea that ADHD is not just a behavioral issue but a neurological condition with observable differences in brain activity.
The differences in activation levels are highlighted in red and yellow, with notable reductions in certain brain regions in the ADHD brain.
- Reduced Frontal Lobe Activity:
- The frontal lobe is responsible for executive functions, such as attention, impulse control, and decision-making.
- In the ADHD brain, there is lower activity in the frontal lobe, which can explain difficulties in focusing, self-regulation, and problem-solving.
- Sensory-Motor Cortex Differences:
- The sensory-motor cortex is involved in processing movement and sensory input.
- Differences in activity levels here could be related to hyperactivity and difficulty in regulating physical movement.
- Lower Cerebellum Activation:
- The cerebellum plays a role in coordination, movement, and cognitive functions like attention and emotional regulation.
- Reduced activity in this area may contribute to difficulty in fine motor control, attention shifts, and impulse regulation.
What does recent research say?
Recent brain imaging studies have revealed several key differences in the brains of individuals with ADHD. Here’s what these differences mean for everyday life:
1. Atypical brain connectivity
Youth with ADHD show heightened connectivity between deep brain structures involved in learning, movement, reward, and emotion (caudate, putamen, and nucleus accumbens) and frontal areas involved in attention and behavior control.
You might experience:
- Difficulty regulating emotions
- Impulsive decision-making
- Challenges in focusing on tasks
- Increased sensitivity to rewards
2. Decreased frontal lobe perfusion
SPECT studies have consistently shown reduced blood flow in the orbitofrontal cortices, anterior cingulate gyri, prefrontal cortices, basal ganglia, and temporal lobes of ADHD patients.
You may notice:
- Problems with planning and organizing
- Difficulty initiating tasks
- Challenges in controlling impulses
- Struggles with time management
3. Functional differences
fMRI studies have identified both hyperactive and hypoactive brain regions in individuals with ADHD compared to those without.
You might experience:
- Inconsistent performance in tasks
- Periods of hyperfocus alternating with inattention
- Difficulty switching between tasks
- Challenges in maintaining consistent energy levels
4. Neurotransmitter activity
ADHD brains typically display lower levels of dopamine and norepinephrine, which are crucial for motivation, decision-making, and attention.
You may notice:
- Reduced motivation for tasks that aren’t immediately rewarding
- Difficulty sustaining attention on less stimulating activities
- Challenges in regulating mood and energy levels
- Impulsive behavior in pursuit of stimulation
5. Structural differences
Multiple studies, including those from the ENIGMA consortium, have found that children with ADHD have smaller global and regional brain structural indices compared to typically developing children.
You might experience:
- Challenges with specific cognitive functions
- Difficulties in processing certain types of information
- Potential delays in some aspects of cognitive development
6. Reduced brain volume
Research has shown that individuals diagnosed with ADHD in adolescence had reduced brain volume as adults, leading to poorer memory function.
You may notice:
- Difficulties with working memory
- Challenges in recalling and following multi-step instructions
- Problems remembering appointments or deadlines
- Struggles with academic or work tasks that rely heavily on memory
Remember, while these brain differences are associated with ADHD, they don’t define you as a person. Many individuals with ADHD lead successful, fulfilling lives by understanding their unique brain wiring and developing strategies to work with their strengths.
Citations:
- https://www.psypost.org/adhd-linked-to-unusual-brain-connectivity-patterns-in-large-scale-neuroimaging-study/
- https://www.additudemag.com/current-research-on-adhd-breakdown-of-the-adhd-brain/https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2013.00192/full
- https://www.cam.ac.uk/research/news/differences-in-brain-structure-and-memory-suggest-adolescents-may-not-grow-out-of-adhd
- https://medicalxpress.com/news/2024-01-neuroimaging-cumulative-brain-wide-effects.html
- https://www.nature.com/articles/s41398-021-01301-1
- https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2203835
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7502360/
- https://www.nih.gov/news-events/news-releases/nih-researchers-identify-brain-connections-associated-adhd-youth
- https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2021.725788/full
- https://creyos.com/blog/adhd-brain-scan
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7879851/
- https://www.additudemag.com/current-research-on-adhd-breakdown-of-the-adhd-brain/
