There is really only one reason ADHD is underdiagnosed in women as opposed to men: patriarchy. Below is data to support this conclusion, but if you remember nothing else (and hey, we know memory recall with ADHD can be a challenge), just remember the reason men get diagnosed 3x more on average than women is that they're men, period.

According to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders, ADHD symptoms are generally described as three subtypes: predominantly hyperactive, predominantly inattentive, and combined type. Inattentive ADHD symptoms are still commonly confused and incorrectly diagnosed by medical professionals who mistake them for mood disorders, anxiety, or other related condition. Inattentive ADHD is also more common in girls and women than it is in boys and men. This is part of the problem.

Inattentive ADHD symptoms according to the CDC:

• Often fails to give close attention to details or makes careless mistakes in schoolwork, at work, or with other activities.

• Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (e.g., loses focus, side-tracked).

• Often has trouble organizing tasks and activities.

• Often loses things necessary for tasks and activities

Hyperactive ADHD symptoms according to the CDC:

• Often fidgets with, taps hands or feet, or squirms in seat.

• Is often “on the go” acting as if “driven by a motor”.

• Often has trouble waiting their turn.

• Often leaves seat in situations when remaining seated is expected.

Because inattention is much more subtle than hyperactivity, this may be why boys are almost three times more likely than girls to be diagnosed with ADHD. By the time they reach adulthood that gap shrinks to two to one. This is likely because girls are often diagnosed later in life, compared to boys. Overall, women are still underdiagnosed as having ADHD by 50 to 70%.

In fact, ADHD was originally seen as only a boys' or men's disorder and early research on ADHD studied only male patients. Some reports state that ADHD in women wasn’t meaningfully researched until 1995 by Julia Rucklidge and Bonnie Kaplan.

The Bottom line:

The underlying chemistry in the brain of ADHD is the same for men and women. Both have difficulties with planning, organization, recalling details, and paying attention. But how ADHD behaviors are expressed will often vary between men and women due to cultural and social gender norms.