Listen to this story:

Except for her family and closest friends, no one in Jennifer’s various circles knows that she is on the spectrum. Jennifer was not diagnosed with autism until she was 45 — and then only because she wanted confirmation of what she had figured out for herself over the previous decade. Most of her life, she says, she evaded a diagnosis by forcing herself to stop doing things her parents and others found strange or unacceptable. (For privacy reasons, Jennifer asked that we not use her last name.)

Over several weeks of emailing back and forth, Jennifer confides in me some of the tricks she uses to mask her autism — for example, staring at the spot between someone’s eyes instead of into their eyes, which makes her uncomfortable. But when we speak for the first time over video chat one Friday afternoon in January, I cannot pick up on any of these ploys.

She confesses to being anxious. “I didn’t put on my interview face,” she says. But her nervousness, too, is hidden — at least until she tells me that she is tapping her foot off camera and biting down on the chewing gum in her mouth. The only possible ‘tell’ I notice is that she gathers up hanks of her shoulder-length brown hair, pulls them back from her face and then lets them drop — over and over again.

In the course of more than an hour, Jennifer, a 48-year-old writer, describes the intense social and communication difficulties she experiences almost daily. She can express herself easily in writing, she says, but becomes disoriented during face-to-face communication. “The immediacy of the interaction messes with my processing,” she says.

“Am I making any sense at all?” she suddenly bursts out. She is, but often fears she is not.

To compensate, Jennifer says she practices how to act. Before attending a birthday party with her son, for example, she prepares herself to be “on,” correcting her posture and habitual fidgeting. She demonstrates for me how she sits up straight and becomes still. Her face takes on a pleasant and engaged expression, one she might adopt during conversation with another parent. To keep a dialogue going, she might drop in a few well-rehearsed catchphrases, such as “good grief” or “go big or go home.” “I feel if I do the nods, they won’t feel I’m uninterested,” she says.

Over the past few years, scientists have discovered that, like Jennifer, many women on the spectrum ‘camouflage’ the signs of their autism. This masking may explain at least in part why three to four times as many boys as girls are diagnosed with the condition. It might also account for why girls diagnosed young tend to show severe traits, and highly intelligent girls are often diagnosed late. (Men on the spectrum also camouflage, researchers have found, but not as commonly as women.)

Nearly everyone makes small adjustments to fit in better or conform to social norms, but camouflaging calls for constant and elaborate effort. It can help women with autism maintain their relationships and careers, but those gains often come at a heavy cost, including physical exhaustion and extreme anxiety.

“Camouflaging is often about a desperate and sometimes subconscious survival battle,” says Kajsa Igelström, assistant professor of neuroscience at Linköping University in Sweden. “And this is an important point, I think — that camouflaging often develops as a natural adaptation strategy to navigate reality,” she says. “For many women, it’s not until they get properly diagnosed, recognized and accepted that they can fully map out who they are.”

Even so, not all women who camouflage say they would have wanted to know about their autism earlier — and researchers acknowledge that the issue is fraught with complexities. Receiving a formal diagnosis often helps women understand themselves better and tap greater support, but some women say it comes with its own burdens, such as a stigmatizing label and lower expectations for achievement.