The school day ended at 3:10. Emma had been in that third-row seat since 8:15, and for most of those hours she had done what she always did: tracked the lesson carefully, noted where the teacher’s gaze landed, kept her pen moving, and held the expression that said she was following. A few minutes before the bell, she made one last visual sweep of the room to confirm she hadn’t misunderstood when they would turn in the lab worksheet, whether there was reading assigned, when the test was.

She was right on both counts. The teacher smiled at her on the way out.

What the teacher saw was a conscientious, attentive student. What that teacher could not see was the cognitive overhead behind the face: the 45 minutes of suppressing the pull toward the scraping chair two rows over; the partial sentence heard during the transition between topics that she couldn’t release because it didn’t fit what came before it; the monitoring running continuously in the background — of whether her expression was doing the right thing at the right time. She had a homework list. She was also, quietly, exhausted in a way she had learned to keep entirely to herself.

Emma is a composite — not a patient record. But the structure of what she experienced is consistent with a pattern that a growing body of research has documented among females with ADHD: a presentation that is invisible precisely because it is carefully managed, that exacts a significant ongoing cost, and that tends to go unrecognized long past the point where a comparable presentation in a male peer would have generated a referral.

A Symptom Profile Shaped by a Different Population

The criteria currently used to diagnose ADHD in the United States were built on a research base drawn predominantly from male samples. The studies that informed the DSM criteria from the 1980s through the 1990s recruited heavily from referred clinical populations — children sent for evaluation because their behavior was disrupting classrooms and families. The presentation those studies found most often was hyperactive-impulsive: loud, visible, external. The criteria they produced encoded that presentation.

This does not mean the criteria are wrong for everyone they capture. It means they were calibrated against a specific signal — and that calibration has consequences for detecting a different signal. A child who is disruptive gets referred. A child who is quiet and hands in homework on time generates fewer referrals, regardless of the cognitive effort that being quiet and handing in homework required.

The point is not that earlier research was careless. It is that research populations shape what gets found. When the samples skew male, the criteria they produce become better detectors of one presentation pattern than another — not by design, but by the arithmetic of who was in the room.

Internalizing Versus Externalizing: Why One Pattern Disappears

The distinction between externalizing and internalizing symptoms is not about degree of difficulty. It is about where the difficulty appears.

Externalizing symptoms are visible: leaving a seat, calling out, failing to wait, physical restlessness that creates friction with external environments. That friction generates referrals and diagnoses.

Internalizing symptoms are not visible. A student whose attention is drifting while her eyes stay on the board creates no friction for anyone but herself. Rumination. Excessive self-monitoring. Emotional dysregulation that is contained rather than expressed. These impose real costs on the person experiencing them — but they do not announce themselves to the room.

Research consistently shows that females with ADHD present more often with internalizing profiles than males. They also carry higher rates of anxiety and mood disorder comorbidities. A 2024 study by Catarina Skoglund and colleagues, published in the Journal of Child Psychology and Psychiatry, drew on data from 85,330 individuals with ADHD in Stockholm County. It found that females with ADHD had comorbid anxiety disorders at a rate of 50.4%, compared to 25.9% in males. Mood disorder comorbidity was 37.5% in females versus 19.5% in males (Skoglund et al., Journal of Child Psychology and Psychiatry, 2024).

Whether the anxiety comorbidity is a consequence of living with unrecognized ADHD, an independent parallel condition, or both in different proportions for different individuals — the study documents an association, not a causal sequence. Both questions are open.

Masking: The Work Behind the Face

The term masking has entered popular discourse around neurodivergence broadly, and it is now used loosely enough that the underlying research finding can be lost. What the research actually shows is more specific than a general tendency to hide differences.

A 2024 study by McKinney and colleagues, available through PubMed Central (PMC11669776), examined 119 girls between the ages of 11 and 14 — 70 neurodivergent and 49 neurotypical. The researchers measured camouflaging across its components, including assimilation: the active effort to match neurotypical behavioral norms. Neurodivergent girls showed significantly higher assimilation scores than their neurotypical peers, and age had a medium-sized effect on camouflaging intensity — with the behavior increasing as the girls got older (McKinney et al., 2024). This is not passive disappearance. It is effortful adaptation that draws on resources.

A 2025 qualitative study published in the British Journal of Psychiatry (PMC12550658) by Williams and colleagues asked 12 young adults with ADHD, ages 18 to 25, to describe their experience in their own words. Masking emerged as a central theme. One participant described the arc directly: “I think I masked quite a lot until I got to puberty, and I just couldn’t do it anymore” (Williams et al., British Journal of Psychiatry, 2025). The study identified four organizing themes: socially-oriented symptoms, social impacts, masking, and context-dependence. The context-dependence finding is significant — many participants described symptoms that appeared clearly in structured environments while remaining less visible in unstructured ones. This situational variability makes the pattern harder to detect in a standard clinical assessment, which often samples only a narrow slice of a person’s environments.

The cognitive cost of sustained masking is real. Whether masking is the primary driver behind the elevated anxiety comorbidity rates documented by Skoglund and colleagues is not yet established in a single study design. The two findings sit alongside each other in the literature; the mechanism linking them remains a question.

Estrogen, Dopamine, and How Symptoms Shift Across the Lifespan

ADHD has a documented dopaminergic component — dopamine signaling in the prefrontal cortex and basal ganglia is consistently implicated in its neurobiology. This matters for understanding sex differences because estrogen is not neurologically neutral.

A 2025 review by Kooij and colleagues published in Frontiers in Global Women’s Health (PMC12277363) examined the relationship between estrogen and ADHD across the female lifespan. They documented that estrogen modulates dopamine synthesis, its maintenance, and the inhibition of its degradation — meaning estrogen levels directly influence the neurotransmitter system most closely associated with attention regulation. This creates a lifespan pattern with specific pressure points.

In adolescence, the onset of hormonal cycling introduces fluctuations not present in childhood. Symptoms that were manageable under stable conditions may intensify during phases of lower estrogen. The researchers noted increased hyperactivity and impulsivity during the early follicular and luteal phases of the menstrual cycle.

The effects are pronounced at perimenopause. Kooij and colleagues reported that 70% of the women in their sample described life-altering ADHD impacts during perimenopause — a period when estrogen declines substantially and dopaminergic modulation is affected accordingly (Kooij et al., Frontiers in Global Women’s Health, 2025). This is not evidence that menopause causes ADHD. It means the hormonal changes of midlife can shift the threshold at which existing ADHD symptoms become functionally impairing — often dramatically, and often at an age when a woman has compensated successfully for decades and has no prior diagnosis.

The Kooij et al. paper is a review, not a clinical trial. The findings it synthesizes draw on varied study designs and populations. The 70% figure comes from a specific sample and may not generalize broadly; it is reported here with that caveat intact.

What the Diagnostic Gap Looks Like in the Data

Two recent studies document the average difference in diagnosis age between males and females with ADHD.

Skoglund and colleagues (2024), drawing on the Stockholm County dataset of 85,330 individuals, found that females received an ADHD diagnosis at an average age of 23.5 years, compared to 19.6 years for males — a difference of approximately four years. The researchers noted the gap appeared to be narrowing in more recent birth cohorts, possibly reflecting increased clinical awareness, though the data cannot establish why.

A separate analysis presented at the European College of Neuropsychopharmacology (ECNP) Congress in Barcelona in 2025, by Amoretti and colleagues, examined 900 adults and found that women were diagnosed at an average of 28.96 years compared to 24.13 years for men — a gap of nearly five years. In addition to the later diagnosis, women in that study showed higher symptom severity scores, worse psychosocial functioning, and greater disability scores, with elevated rates of depression and anxiety (Amoretti et al., ECNP 2025).

These are population averages. They do not predict what will happen for any individual. Some females are diagnosed in childhood; some males are diagnosed in adulthood. What the averages reflect is a structural pattern — a tendency in the diagnostic process, not a biological determination. What they suggest, in combination with the comorbidity data, is that years of unrecognized difficulty carry their own costs: the anxiety that accumulates during the years of compensating without a framework; the identity narrative that forms around the assumption that effortful management is just who you are.

What the Research Does Not Yet Establish

The pattern documented across these studies is real at the group level. It is not a prediction about any individual.

The Skoglund et al. data come from Stockholm County — one healthcare system in one country. Referral patterns, diagnostic thresholds, and access to assessment differ substantially across settings. Comorbidity rates and diagnosis age gaps documented in Sweden may not map directly onto populations elsewhere.

The McKinney et al. camouflaging study examined 119 girls — a relatively small sample. The findings are consistent with the broader masking literature, but the precise role of camouflaging in ADHD detection specifically (as opposed to autism, where the masking research base is larger) is still being established. Whether the assimilation behavior documented in that age range persists, intensifies, or changes shape in adulthood has not been followed longitudinally in the same cohort.

The Kooij et al. review synthesizes a heterogeneous literature on estrogen and ADHD. The estrogen-dopamine relationship is mechanistically plausible and supported by converging evidence; randomized clinical evidence on hormone management for ADHD in perimenopausal women is sparse. Extrapolating from the review to specific clinical recommendations requires more evidence than the review itself provides.

The diagnostic gap findings document that females are diagnosed later on average — but they do not establish why. Referral patterns, assessment design, internalizing presentation, masking, hormonal variability, and cultural expectations around female behavior are all plausible contributors. The weight of each factor has not been isolated.

Increased public awareness of female ADHD presentations has had real benefits: more women have pursued evaluation who otherwise would not. It has also produced popular characterizations — of what female ADHD looks like, who has it, and what it means — that outrun what the research currently supports at the level of individual prediction. The findings summarized here provide a framework for taking the question seriously. They do not answer it for any particular person.