The Great Symptom Sandwich: Why “I Can’t Focus” Doesn’t Automatically Mean ADHD

I recently wrote a piece on rejection sensitivity, and while trying to find a metaphor to describe the term transdiagnostics, I came across two of the internet’s greatest cultural frameworks: the Cube Rule of Food and the Sandwich Alignment Chart (more on that in a second). After I finished writing, I thought it would be a funny and interesting blog post to talk about transdiagnostics a little further and build out this metaphor, so here goes nothing.

We’ve all seen the TikToks and Reels. A relatable creator stares at a pile of laundry or a half-finished email draft, sighing about how their brain has thirty open tabs, three of them are frozen, and there’s music playing from an unknown source.

The comment section inevitably reads: “Oh no, do I have ADHD?”

It’s a fair question. Brain fog and a total inability to sit still or focus are deeply frustrating experiences. But if you walk into a psychiatric clinic and say, “I can’t focus,” jumping straight to an ADHD diagnosis is like ordering a sandwich, getting a hot dog, and calling it a day.

To understand why, we need to talk about transdiagnostics—a fancy medical framework that recognizes how individual symptoms (like a broken focus dial) cut across multiple psychiatric diagnoses rather than belonging exclusively to just one. The metaphor I came up with in my previous rejection sensitivity post was that transdiagnostics is like using flour as an ingredient in bread, cake, pasta, and pizza dough. Flour is essential to all of those recipes, but knowing something contains flour doesn’t tell you what you are eating.

And now, onto the food-metaphor rabbit hole.

Part 1: The Sandwich Alignment Chart of Psychiatry

Here it is in all its glory:

• Structure Purist / Ingredient Purist: Only a traditional ham and cheese on sliced bread counts as a sandwich.
• Structure Rebel / Ingredient Rebel: A Pop-Tart is a sandwich. An Oreo is a sandwich. Everything is a sandwich.

For decades, traditional psychiatry operated like a Structure Purist. The Diagnostic and Statistical Manual of Mental Disorders (DSM) drew neat little boxes. If you have Symptoms A, B, and C, you are in the ADHD Box. If you have Symptoms D, E, and F, you are in the Depression Box. The boxes weren’t supposed to touch.

But human brains are notorious for their rebellious streak. They don’t care about the DSM’s structural rules.

Enter the Transdiagnostic Approach. This framework is the Structure Rebel of mental health. It challenges the idea that every psychiatric diagnosis is a completely distinct entity. Instead, it looks at the underlying biological processes, emotional patterns, and symptoms that overlap across many different conditions.

When you say “I can’t focus,” a transdiagnostic clinician doesn’t immediately hand you an ADHD screening form. They recognize that inattention is a transdiagnostic symptom. It’s the “carbohydrate exterior” that could be wrapping a dozen entirely different fillings.

Part 2: The Cube Rule of “Inattention”

Let’s continue with the example of using “inattention” as the symptom. To truly classify why your focus is broken, we have to apply the Cube Rule. For the uninitiated, the Cube Rule states that all food can be classified into six archetypes based on where the structural starch (the bread/crust) is placed. A sandwich has starch on the top and bottom; a taco has starch on the bottom and two sides; a calzone has starch completely enclosing the middle. In our metaphor, the core symptom is the starch.

The transdiagnostic approach uses the Cube Rule to show that just because you see “starch” (a symptom like difficulty focusing), you cannot immediately assume you are looking at a standard sandwich (ADHD). The structural meaning of that symptom changes entirely depending on the “filling” packed inside it.

Let’s look at how the exact same symptom—”difficulty focusing”—changes structural meaning depending on what is actually causing it.

1. The Sandwich (ADHD)

• The Structure: Starch on top and bottom.
• The Filling: Dopamine deficit, executive dysfunction, and an unremitting timeline.
• The Reality: This is classic, textbook ADHD. The focus issues are structural, neurodevelopmental, and lifelong.
• Key Differentiator: To be a true “ADHD Sandwich,” the symptoms must have started early (before age 12), be persistent and unremitting across your whole life, and show up in multiple settings, like both at home and at work. In ADHD, your brain struggles to focus because the starch forms a rigid, lifelong container. Your attention wanders off task, fails to follow through, and has difficulty sustaining focus on things that aren’t immediately stimulating. The DSM-5 notes that people with ADHD are often preferentially drawn to novel, high-stimulation activities, but the core issue is broader than just novelty-seeking.

2. The Taco (Anxiety)

• The Structure: Starch on the bottom and two sides, open at the top.
• The Filling: Chronic worry, physical restlessness, endless mental loops of overthinking and catastrophizing
• The Reality: The starch (inattention) is forced upward and outward into a taco shell shape because it is being crowded out by a massive, overflowing filling of dread. You can’t focus, but it’s not because your brain lacks dopamine. It’s because your brain is currently being held hostage by a swarm of bees.
• Key Differentiator: In anxiety disorders, inattention is driven by worry, constant rumination, and mental preoccupation. Your brain is too busy simulating 45 worst-case scenarios to care about your spreadsheet.

3. The Quiche (Depression)

• The Structure: Starch on the bottom and sides, filled with a dense custard.
• The Filling: A dense, heavy custard of low motivation, persistent sadness, and anhedonia (inability to feel pleasure).
• The Reality: The inattention crust holds up a massive, heavy weight of depressive symptoms that slows down your brain’s processing speed entirely.
• Key Differentiator: Unlike the lifelong timeline of ADHD, depressive inattention is episodic, meaning it anchors itself to your mood cycles rather than tracking back to childhood. But there is an important caveat here: cognitive recovery after depression is often incomplete. A randomized study published in The Lancet Psychiatry found that cognitive deficits — including problems with focus and memory — showed little meaningful improvement after 8 weeks of antidepressant treatment, even among patients whose mood symptoms responded. In other words, the emotional fog may lift, but the cognitive fog often lingers.

4. The Toast (Sleep Deprivation & Sleep Apnea)

• The Structure: Starch on the bottom only. Single exposed layer.
• The Filling: Absolute physical exhaustion and systemic oxygen deprivation
• The Reality: There are no complex emotional fillings here. The “toast” of inattention is lying completely flat because your brain simply lacks the energy to stand up.
• Key Differentiator: Sleep disorders like insomnia or obstructive sleep apnea completely mimic ADHD. If you fix the sleep, and the focus magically returns, you were probably just dealing with burnt toast all along. Adults with ADHD report significant sleep issues as a core feature of their condition but not a separate diagnosis. Fixing sleep makes the underlying ADHD easier to see.

5. The Calzone (Trauma & PTSD)

• The Structure: Starch fully enclosing the ingredients.
• The Filling: Hyperarousal, trauma triggers, and deep-seated emotional pain.
• The Reality: The inattention acts as a thick, protective, fortress-like outer shell designed to keep the vulnerable, painful internal trauma symptoms hidden from view.
• Key Differentiator: Hyper-vigilance, irritability, and restlessness look identical to ADHD—especially in kids. But structurally, the calzone’s shell is formed because the brain is constantly scanning the environment for threats, leaving zero bandwidth left over for sustained attention.
• That said, ADHD and PTSD are not always an either-or situation. Some studies estimate that up to 36% of adults with PTSD also have comorbid ADHD. A 2026 study of over 700,000 youth found that stimulants were actually associated with the most favorable outcomes, even in kids who had both ADHD and PTSD. The calzone might sometimes have a sandwich hiding inside it.

6. The Salad (Situational/Contextual Stress)

• The Structure: No starch. No structural container at all.
• The Filling: Raw life circumstances—a brutal work deadline, a divorce, a cross-country move, grief, financial collapse, or navigating three kids under five.
• The Reality: There is no psychiatric “shell” here. The inattention is entirely real, but it isn’t wrapped in a core neurodevelopmental or emotional condition. It’s just a massive pile of raw ingredients sitting on a plate with no bread in sight.
• Key Differentiator: Sometimes you can’t focus simply because life is genuinely overwhelming, not because something is structurally wrong with your brain’s wiring. The DSM-5-TR includes “Adjustment Disorders” for exactly this reason—clinically significant emotional or cognitive distress in response to an identifiable life stressor that doesn’t meet the full criteria for another mental disorder. Once the stressor passes or you adapt to the new reality, the focus issues typically clear up. There is no sandwich and no taco here. It’s just a salad that needs time, a little grace, and maybe some things like therapy, social support, or a temporary break from the chaos.

A Note on Combo-Platters & Fusion Foods

Before we move on, a critical disclaimer: real human brains rarely present as a single a la carte food item archetype. In clinical practice, patients frequently show up as combination platters:

• Genuine ADHD with a side of anxiety
• Depression wrapped around undiagnosed sleep apnea
• PTSD layered on top of a neurodevelopmental condition that’s been there since childhood

The cube rule is a fun way to understand why a single symptom can have wildly different causes, but don’t let the metaphor trick you into the same categorical thinking we’re trying to avoid. Sometimes it really is two things at once.

Furthermore, inattention is just one example of a transdiagnostic starchy ingredient. We could run this exact same Cube Rule exercise using Anxiety as our core starch, and watch it flip shapes across different diagnoses:

• Anxiety as a Taco (Generalized Anxiety Disorder), where the structural worry is the primary dish.
• Anxiety as a Sandwich (ADHD), where the internal restlessness and panic are actually the structural byproduct of a lifetime of frantically masking executive dysfunction.
• Anxiety as a Calzone (PTSD), where the anxiety acts as a protective, hyper-vigilant shell enclosing a core of past trauma.

Because these mental health “ingredients” can take on so many shapes, they easily melt together in the wild. Think of it like a Kimchi Quesadilla (Ok, I’m a foodie). You aren’t just eating Mexican food, and you aren’t just eating Korean food. The sharp, fermented heat of the kimchi blends entirely with the melted cheese inside the tortilla. You can’t separate them out without making a massive mess, and eating it gives you a completely unique flavor profile that neither ingredient could achieve on its own.

In psychiatry, this is what we call comorbidity. When you have multiple conditions overlapping, they don’t sit quietly in separate compartments on your plate. They fuse. Your anxiety changes how your ADHD looks, and your ADHD feeds your anxiety. A transdiagnostic approach doesn’t just look for one isolated food category; it learns to decode the entire fusion recipe.

The “Vibe Check” Diagnosis is Clinically Dangerous

Because symptoms overlap so heavily, diagnosing someone based on a single complaint is incredibly risky. The DSM-5-TR explicitly warns that ADHD should never be diagnosed if the symptoms are “better accounted for by another mental disorder.”

If a clinician uses a lazy, “ingredient purist” approach, a few things go wrong:

• The Stimulant Trap: Someone takes a friend’s Adderall, notices they can focus better, and assumes, “Aha! I must have ADHD!” Except stimulants don’t work the way most people think. While early research suggested they enhanced concentration in almost everyone, more recent evidence tells a potentially different story. A 2020 meta-analysis found that methylphenidate’s cognitive enhancement effects in healthy adults are actually quite small and domain-specific, not the dramatic boost people expect. Even more striking, a 2026 placebo-controlled trial found no significant neuropsychological improvement from stimulants in college students without ADHD, suggesting that the perceived benefit may be largely a placebo effect. A positive response to a stimulant is not a diagnostic confirmation. It may just mean you believed that it would work.
• Treating the Wrong Layer: If your focus issues are actually a “Taco” (Anxiety) or a “Quiche” (Depression), giving you heavy stimulants without addressing the core emotional distress is just going to make you really fast at being anxious.

The Safe Kitchen Strategy

When a doctor looks at a messy symptom profile through a transdiagnostic lens, they usually recommend a three-part approach for adults:

1. Check the Expiration Date: Confirm the focus issues actually started before age 12.
2. Use a Wide-Angle Lens: Screen broadly for depression, anxiety, mania, trauma, and sleep issues using tools like the DSM Cross-Cutting Symptom Measure.
3. Clean the Prep Station First: If someone has both severe anxiety/depression and focus issues, the safest clinical strategy is to treat the mood or anxiety disorder first. If the anxiety resolves and your client or patient can suddenly read a book again, the focus issues may have been driven by anxiety all along making it a very sneaky taco. Keep in mind that up to 50% of people with ADHD also have co-occurring anxiety disorders. Sometimes treating the anxiety doesn’t make the focus issues just disappear, but instead clears the fog enough to reveal the sandwich that was underneath the whole time. Resolution of anxiety doesn’t automatically rule out ADHD, though it does clarify the picture for us.

The Takeaway

Mental health isn’t a pre-packaged Lunchable where every symptom stays cleanly in its own compartment. It’s a chaotic, overlapping buffet.

The next time you find yourself utterly unable to focus on a task, step back and check your structural alignment. Are you genuinely looking at a neurodevelopmental lifelong sandwich? Or are you just dealing with an anxiety taco, a depressive quiche, or a severe case of sleep-deprived burnt toast?

Your brain deserves a thorough evaluation. A hot dog is a hot dog is a hot dog. A quiche could never.