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Why underdiagnosis of ADHD in girls and women is structural

The agreeableness gap: why girls mask ADHD more effectively than boys

The diagnostic gap between boys and girls with ADHD is not a mystery waiting to be solved. It is a predictable outcome of criteria designed around male presentations, applied within social systems that reward female compliance. The result is a structural underdiagnosis that has persisted for decades — and continues despite widespread awareness that it exists.

One of the most robust findings in personality psychology is the gender difference in agreeableness. Across cultures, women consistently score higher than men on this Big Five personality dimension — with effect sizes ranging from d = 0.35 to d = 0.59 depending on the study. This is not a small or contested finding. It replicates across 55 nations, persists into old age, and — counterintuitively — is larger in more gender-egalitarian societies where women have greater freedom to express individual differences.

Agreeableness is not a single trait. It encompasses compassion, cooperation, trust, and compliance. The compliance component is particularly relevant here. Research shows that women score higher than men on both compassion and politeness — the latter describing the tendency to show respect to others, refrain from taking advantage, and defer to social expectations. Women are, on average, more trusting and more compliant than men.

This matters for ADHD because compliance is precisely what masks it. A girl with ADHD who has learned to suppress her restlessness, manage her impulses through sheer effort, and present as cooperative will not trigger the referral pathways designed to catch “disordered” and disruptive behaviour. She will be praised for being adaptable. But she will be told she is “sensitive” when she melts down after school. And she will be encouraged to try harder — and she will, because that is what agreeableness does.

The agreeableness gap is not a flaw in women. It is a personality dimension with evolutionary and social roots that serves many adaptive functions. But when combined with ADHD — a condition that creates a genuine mismatch between internal experience and external demands — it produces a masking effect that delays recognition for years or decades.

Diagnostic criteria built on male samples miss female presentations by design

The diagnostic criteria for ADHD (and for autism) were developed primarily using studies of boys. This is not historical trivia — it is the origin of a structural problem that persists today. The behaviours that define ADHD in clinical manuals — hyperactivity, impulsivity, disruptive conduct, etc — are the behaviours that got boys referred for assessment. They are the presentations that teachers noticed, that parents complained about, that clinicians learned to recognise.

Girls with ADHD present differently. Instead of visible hyperactivity, they experience constant mental chatter. Instead of disruptive impulsivity, they show emotional dysregulation that reads as “sensitivity.” Instead of defiance, they display perfectionism and people-pleasing, and the list goes on — compensatory strategies that exhaust them while making their difficulties invisible. A 2025 qualitative study in the British Journal of Psychiatry found that young women with ADHD described symptoms that were “more socially oriented and internalised” than current diagnostic criteria capture — difficulties like losing track of thoughts in conversation, non-disruptive fidgeting such as doodling, and internalised frustration rather than externalised anger.

The criteria themselves create the underdiagnosis. When the diagnostic threshold is calibrated to male presentations, female presentations fall below it — not because they are less impairing, but because they are less visible to observers trained on the wrong template. A 2025 integrative review in BMC Women’s Health stated it directly: “Both gender stereotypes and societal expectation and conditioning contribute to masking behaviours in girls. This results in underdiagnosis of ADHD, with women typically receiving a diagnosis later in life than men.”

The diagnostic ratio reflects this. In childhood, boys are diagnosed at roughly twice the rate of girls. By adulthood, this narrows to around 1.6:1 — not because ADHD resolves in boys, but because women are finally being recognised after years of being missed. As one Monash University study concluded: “This sex-based disparity in ADHD prevalence rates may reflect misdiagnosis and underdiagnosis of females, rather than a male disposition to ADHD.”

Masking as a survival strategy, and its compounding costs

Masking is not a choice made freely. It is a survival strategy developed in response to environments that punish visible difference. For girls with ADHD, masking begins early — often before they have any framework for understanding why they feel different from their peers.

The process is straightforward. A girl notices that her restlessness, her emotional intensity, her difficulty following instructions, her tendency to blurt things out — all of these provoke negative responses. She learns to suppress them. She watches neurotypical peers and imitates their behaviour. She develops scripts for social interaction. She channels her hyperactivity into internal anxiety rather than external movement. She becomes “the good girl” — and the effort required to maintain this performance is invisible to everyone except her.

Teachers see a compliant student. Parents see meltdowns after school — the release of a day’s worth of suppressed impulses — but attribute them to tiredness or sensitivity. Clinicians, if consulted at all, see a presentation that does not match the ADHD template they were trained on. The masking works, in the narrow sense that it prevents referral. But it works at a cost that compounds over time.

The costs are well-documented. A 2025 study in Scientific Reports found that women with late-diagnosed ADHD reported “internalising criticism” throughout their lives, describing “disconcertingly low self-esteem” characterised by guilt, shame, and negative self-perception. Participants described diagnosis as revelatory — “their lives finally making sense” — with improvements in self-esteem and a sense that life was “more worth living.” The relief of diagnosis in adulthood is itself evidence of the damage caused by its absence in childhood.

The masking literature consistently identifies the same downstream consequences: higher rates of anxiety and depression, maladaptive coping strategies including self-medication, greater vulnerability to manipulation and abuse, and exhaustion from the constant effort of monitoring and adjusting behaviour. A 2025 meta-analysis confirmed that females display consistently higher camouflaging scores than males — and that this camouflaging, while adaptive in intent, has “long-term negative effects on psychological well-being.”

The compliance trap: from "trying harder" to later diagnosis

Recent research on effort and ADHD illuminates a mechanism that connects agreeableness, masking, and underdiagnosis. A 2026 study by Torres and Toplak in the Journal of Attention Disorders found that children with ADHD consistently report lower effort ratings across cognitive tasks — not because the tasks are harder for them, but as a trait-level tendency that persists regardless of task type.

The framing matters here. “Effort” as measured in these studies is not raw exertion. It is compliance with externally imposed structure — the willingness to engage with tasks defined by others, on timelines set by others, toward goals that may hold no intrinsic interest. Neurotypical children report higher effort than neurodivergent children because they comply more readily with these structures. Children with ADHD require intrinsic connection to a task before effort becomes available — a pattern consistent with interest-based motivation and monotropic attention.

Now add the agreeableness gap. Girls, on average, are more compliant than boys. Girls with ADHD who have high trait agreeableness will push harder to meet external expectations — will report “trying” even when the trying is unsustainable — and will therefore appear to be coping even when they are not. The effort is real. The compliance is real. The appearance of adequacy is real. What is not real is the assumption that this performance can be maintained indefinitely, or that its maintenance indicates an absence of underlying difficulty.

This is the compliance trap. Higher agreeableness produces higher apparent effort. Higher apparent effort produces lower likelihood of referral. Lower likelihood of referral produces later diagnosis. Later diagnosis produces longer exposure to the consequences of unrecognised ADHD — the internalising problems, the maladaptive coping, the self-blame for difficulties that were never personal failings, etc.

The Torres and Toplak study sample was approximately 70% male — itself a reflection of the referral bias that produces male-skewed research samples. The study’s own limitations section noted that girls with ADHD may have higher internalising problems and lower self-efficacy than boys — precisely the pattern that would be expected if girls are masking more effectively and paying a higher psychological price for doing so.

The structural nature of this underdiagnosis means that awareness alone will not fix it. Telling clinicians that girls present differently does not change criteria designed around boys. Telling teachers to look for internalised symptoms does not change reward structures that favour compliant behaviour. Telling girls that masking is harmful does not change the social environments that punish visible difference.

What would change it is diagnostic criteria that capture female presentations as valid ADHD — not as atypical variants of a male norm. What would change it is referral pathways that do not depend on disruptive behaviour to trigger neurodiversity assessments. What would change it is recognition that the agreeableness gap is not a protection against ADHD but a risk factor for its concealment.

The underdiagnosis of ADHD in girls and women is not accidental. It is structural — built into criteria, reinforced by social expectations, and maintained by systems that read compliance as wellness. Changing it requires changing the structures, not just the awareness of those operating within them.