You sit down to do your taxes. Within four minutes you are reorganizing your bookshelf by colour. You are not lazy. You are not broken. And — I promise you — you are not the only adult who has alphabetized a spice rack to avoid a spreadsheet.

Now the opposite. That same brain that couldn't survive a spreadsheet will happily disappear into a video game, a true-crime documentary, or a group chat argument for four straight hours. No snacks. No bathroom breaks. Fully absorbed.

If attention were one dial — a volume knob you simply turn up when you try harder — that shouldn't be possible. You can't be too broken to focus and capable of hyperfocus at the same time.

Unless attention was never one dial to begin with.

Here's what your brain has been hiding from you: attention isn't a single switch. It's a small crew running a live broadcast, in real time, with several different jobs happening at once. Someone decides what's worth airing. Someone else watches for something more urgent to cut to. Someone quietly runs the story you weren't even trying to tell yourself. Most days that crew works so smoothly you never notice them. Some days, difficulty in one job disrupts the whole production.

So let's go backstage.

Meet the crew

The first member keeps the lights on at all — your general level of alertness.1 It's the difference between 7 a.m., pre-coffee you, and the jolt that goes through your whole body the second you hear a car horn a little too close. That's not focus. That's the power being on. The power supply is a surprisingly small thing: a compact cluster of cells in your brainstem called the locus coeruleus — Latin for blue spot, which is about as poetic as neuroanatomy gets. It's the brain's main source of norepinephrine, and when a warning signal arrives it fires, and a set of frontal, parietal, and thalamic areas come up to speed.9 The slow-burn kind of alertness — the everyday hum of being awake and available, as opposed to the jolt from the car horn — leans mostly on the right side of that same network.9

The second decides where the cameras point. This is the part that snaps your eyes toward a notification the instant it lights up, before you've consciously decided to look. Useful when it's a smoke alarm. Less useful when it's a text buzzing on the table during your kid's recital. This one runs largely through parietal cortex and a region of frontal lobe called the frontal eye fields — the same neighbourhood that helps aim your actual eyes, though the two jobs overlap rather than being identical — with subcortical structures in the loop too. It also runs on different chemistry than the crew member before it: orienting leans largely on acetylcholine, while alerting answers mainly to norepinephrine.9

Then there's the director — a goal-directed network that keeps the camera pointed where you chose, and holds the storyline long enough to finish it. It's the part of the crew that keeps I am driving to the airport active despite the radio, the traffic, and the sudden conviction that you may have left the stove on. The director works out of what's called the dorsal frontoparietal network — up along the top of the brain, the intraparietal sulcus and superior parietal lobule at the back, wired to the frontal eye fields at the front.2 Yes, the frontal eye fields again — they show up in more than one job on this crew, because aiming your eyes and aiming your attention share real estate. But the job that actually interrupts you runs on a different network entirely, which is where this gets interesting.

And finally, an assistant director whose entire job is to interrupt the broadcast. Most of the time you don't notice this person exists — until you're deep in a task and something genuinely important happens: your name gets called, your kid cries in another room, someone says the word diagnosis. Neuroscientists have described this right-sided network as a circuit breaker for goal-directed attention, pulling the cameras toward something unexpected and relevant.2 It has an address, too: the temporoparietal junction — where the parietal and temporal lobes meet, roughly above and behind your ear — together with ventral frontal cortex, and it's largely the right side doing this job. There's a loop back to the start of this section here, because the same brainstem blue spot that keeps the lights on may also help drive the interrupt; the ventral network's signal has been proposed to depend partly on norepinephrine.2 Damage to this broader attention system can contribute to neglect, where a person stops responding normally to one side of space.

Here's the part that matters most if your focus has ever seemed to just disappear mid-task. There's also a background story running in your head — your inner monologue, your daydreaming, your rehearsed argument with someone who wronged you in 2019. That story has an address as well — a run of midline regions down the middle of the brain: medial prefrontal cortex at the front, posterior cingulate and precuneus at the back. These are the regions that normally quiet down when you lock onto something demanding.10 Which raises the obvious question: what happens when they don't? One influential model of attentional lapses proposes that this default-mode activity sometimes intrudes into goal-directed processing and competes with the task.3 In ADHD, that competition may be harder to regulate. It's a model, not a diagnostic test, but it fits the stop-start experience many people describe.

Which is why so many people with attention difficulties don't say I can never focus. They say: I start focused. Then I drift. Then I catch myself and come back. Then I drift again.

Not a broken dial stuck on low. A mute button that keeps slipping.

The flicker, not the beam

Here's something that might genuinely surprise you: your attention was never a steady beam in the first place. It's a flicker.

Even during sustained attention, performance doesn't stay perfectly flat. Human experiments and direct brain recordings show rhythmic fluctuations in what gets selected, often several times a second. The spotlight samples. It doesn't simply switch on and stay on.

You've lived some version of this — the half-second, mid-sentence, when the thing you were completely sure of is suddenly gone. Or the familiar highway stretch you drove safely but barely encoded, because your mind was somewhere else. Those experiences have more than one cause, so a laboratory rhythm doesn't explain each one by itself. What it does tell us is that the steady feeling of attention is built from a system whose priorities fluctuate moment to moment.

People with ADHD can have more frequent and more impairing lapses. But the flicker itself belongs to human attention. Finding a rhythm in a laboratory does not tell you who has ADHD.

The chemistry behind the medication

So why does medication help, when it does? This is where it gets genuinely interesting — and where I want to clear up one of the most common misunderstandings I hear in my own practice.

There's a small population of brain cells, right behind your forehead, whose entire job is to hold an idea in mind after the thing that triggered it is gone — the mental equivalent of keeping a browser tab open. Say something to a friend, they get distracted, and thirty seconds later you can still hand them the sentence back, mid-thought. That's this system working.

The catch is that those cells depend on a very particular chemical environment. Under very low arousal — or during uncontrollable stress, when catecholamine levels surge — the connections that keep a representation active can weaken.5 That's one mechanism that can contribute to the blank you get mid-sentence in front of an intimidating room. Not a complete explanation for every blank, and certainly not a character flaw.

The same two chemicals almost everyone has heard of, dopamine and norepinephrine, help regulate those prefrontal connections within a narrow window. Picture the feeling right before an exam: some arousal can sharpen you, while too much turns your mind to static. That inverted-U pattern is one reason dose matters. Prescribers titrate carefully because benefit, side effects, safety, and individual response all matter. Maximum is not the goal.

And here's the myth I most want to bust, because I hear it constantly: I tried my friend's Adderall and I focused better than I have in years — doesn't that prove I have ADHD?

It doesn't. The pill can change how focused you feel. In people without ADHD, the measured improvement in actual cognitive performance is much smaller, and some of the apparent benefit shrinks when researchers account for which studies get published.6 Energy and motivation are the more reliable effect — which is exactly why taking someone else's medication can feel so convincing.

A stimulant changing how you feel proves the stimulant has an effect. It says nothing about whether you have ADHD.

The test that doesn't exist

I want to be honest with you about something the wellness industry is not always honest about. There is no blood test, brain scan, or genetic test that can tell you, on its own, whether you have ADHD.

Not for lack of trying. Researchers spent decades looking for one gene responsible for it. That didn't pan out, because attention runs on the combined, tiny influence of hundreds of genes at once, not one lever. They've scanned thousands of brains looking for a visible difference — and yes, on average, there are small differences in certain regions. But on average is doing a lot of work in that sentence. The overlap between people with ADHD and people without it is enormous. No scan can look at one individual brain and hand you a diagnosis.

There was even a brainwave measure, cleared as a diagnostic aid, based on a frequency ratio associated with attention. A meta-analysis found the gap between ADHD and control groups had declined across studies over time, largely because the ratio rose in the control groups.8 The study did not establish why. Its practical conclusion was simpler: the measure could not serve as a reliable stand-alone diagnostic test.

So how does a real diagnosis happen? Through a comprehensive clinical assessment — history across development and settings, current impairment, other possible explanations, and, where available and appropriate, collateral information or old records. A computer attention task can add information, but systematic reviews find these tests are not accurate enough to diagnose ADHD on their own.7 A teenager can struggle through homework and still perform normally during a short, novel task with constant feedback. Someone with insomnia, depression, trauma-related symptoms, or another condition may perform poorly for reasons that are not ADHD.

The test is a piece of the assessment. It is not the assessment.

Back to you

So where does that leave you, if you've read this thinking this sounds like me?

Not with a scan to order, and not with a reason for shame. A brain that struggles with attention isn't a broken brain. It's a crew whose different jobs can struggle under different conditions, in a system that was never a simple dial to begin with. That is genuinely not your fault.

It is, though, your responsibility to do something with knowing it. Not by diagnosing yourself off a quiz you found at midnight, and not by borrowing a friend's prescription to test a theory. By having the actual conversation — with someone trained to ask about your whole life, not just the last fifteen minutes in a quiet room.

The crew running your attention has been working the whole time, even on your worst days. The question isn't whether you can turn the dial up.

It's whether you finally find out who on your crew needs backup.

Sources

  1. Posner M. Imaging attention networks. NeuroImage (2012).
  2. Corbetta M, Shulman GL. Control of goal-directed and stimulus-driven attention in the brain. Nature Reviews Neuroscience (2002).
  3. Sonuga-Barke EJS, Castellanos FX. Spontaneous attentional fluctuations in impaired states and pathological conditions. Neuroscience & Biobehavioral Reviews (2007).
  4. Fiebelkorn IC, Saalmann YB, Kastner S. Rhythmic sampling within and between objects despite sustained attention at a cued location. Current Biology (2013).
  5. Arnsten AFT. Stress weakens prefrontal networks: molecular insults to higher cognition. Nature Neuroscience (2015).
  6. Ilieva IP, Hook CJ, Farah MJ. Prescription stimulants' effects on healthy inhibitory control, working memory, and episodic memory: a meta-analysis. Journal of Cognitive Neuroscience (2015).
  7. Pagán AF, Huizar PY, Schmidt AT. Conner's Continuous Performance Test and adult ADHD: a systematic literature review. Journal of Attention Disorders (2023).
  8. Arns M, Conners CK, Kraemer HC. A decade of EEG theta/beta ratio research in ADHD: a meta-analysis. Journal of Attention Disorders (2013).
  9. Petersen SE, Posner MI. The attention system of the human brain: 20 years after. Annual Review of Neuroscience (2012).
  10. Raichle ME, MacLeod AM, Snyder AZ, Powers WJ, Gusnard DA, Shulman GL. A default mode of brain function. Proceedings of the National Academy of Sciences (2001).

General education about how minds work — not medical advice, and not an assessment of you.