In the opening scene of "Pure," which premiered yesterday on HBO Max, 24-year-old Marnie is giving a speech at her parents' wedding anniversary party, and she fails spectacularly. Her hands are sweating, her speech starts out graceful, but gradually turns into vulgar jokes, and her thoughts become more and more X-rated. At first, I imagined an unspecified guest making out, but I managed to hold back. But then he imagines his father performing oral sex on his childhood friend and goes completely crazy. Then he sees Marnie skipping through town in a glittering dress.

The first few minutes of Pure promise a quirky, racy, and quite funny story. This six-part British series, in which newcomer Charlie Clive plays a lovable Scottish woman trying to make sense of her unwieldy mind, lives up to its promise.

The actual events that inspired Pure, however, are not lighthearted. At its core is a treatise on the debilitating and widely misunderstood anxiety disorder known as Pure Obsessive-Compulsive Disorder. Unlike "classic" OCD, which is characterized by repetitive behaviors such as washing hands or flipping switches, "Pure-O" does not involve visible rituals, but patients experience similar obsessive and often embarrassing worry. They are usually tormented by unwanted thoughts and mental images of acts of a sexual, violent, or profane nature, especially of a seemingly ugly nature.

Shows like "Pure" can help demystify and normalize this condition. As Marnie says in an early episode of the show, having intrusive sexual thoughts can feel like living in a disturbing parallel universe: "It's like 'The Sixth Sense,' but I see naked people instead of dead people." If the oft-quoted reference to this movie makes you laugh, stop for a moment and really think about how you would feel if you couldn't stop thinking about his penis every time you visited your grandfather. Or if every time you played with your toddler, you imagined banging his head against the wall. These thoughts and images would torment you so much that you would not speak a word to anyone. Or you summon up the courage to talk to a doctor or therapist, but the therapist tries to interpret your thoughts, making things even worse. As in the second episode of Pure, when Marnie sees a psychiatrist, he points out that her sexual thoughts mean that she is repressing her homosexuality. In the next scene, Marnie seduces a woman at a gay nightclub and has an incredibly awkward lesbian experience, even though she doesn't really want to.

Despite or because of her many blunders, Marnie is very likable. She is warm, forthright, and eager to move on. When she attends a meeting of recovering sex addicts, she finds that she is different from the others in the room and makes friends easily, played by Joe Cole. And when you learn that Marnie has OCD and can finally understand all the ways her brain has been malfunctioning, you rejoice with her.

Like many patients (open in new tab), Marnie did not learn her symptoms from an expert. She stumbled upon a book about OCD-related ruminations and recognized herself within its pages. Says Dr. Steven Phillipson, director of the Center for Cognitive Behavioral Psychotherapy in New York City, which specializes in OCD. Even today, patients are told by mental health professionals that if they don't have observable rituals, they don't have OCD." Phillipson explains that people with pure OCD do not engage in visible compulsive behaviors, but practice repetitive mental rituals (such as obsessively Googling information related to intrusive thoughts or avoiding certain people or places) to minimize the stress caused by ruminating.

Studies suggest that about 1% of adults have OCD, but this number could be much higher given that pure OCD is largely unknown. While Marnie was able to find answers early in the program, patients in the real world can suffer in silence for years before seeking help or receiving a correct diagnosis. (Like "classic" OCD, "pure OCD" usually develops before age 25, often in childhood or adolescence.)

That is exactly what happened to Rose Cartwright, and her 2015 memoir, aptly named "Pure" (opens in new tab), is the inspiration for the new show. Cartwright, now a mental health activist based in London, began suffering from violent sexual thoughts as a teenager. 'I was a bit of a mess,' Cartwright tells Marie-Claire. 'Those years shredded my confidence and my ability to relate to people. It was traumatic and I am still on a healing journey." The working-class town in the West Midlands of England where she grew up "had nothing in terms of resources or information. So it took seven years for Cartwright to understand that she had a form of OCD, consulting Wikipedia and, later, CBT therapy. Shortly after learning of his symptoms, Cartwright contributed a harrowingly honest account of his experience to The Guardian (which at the time used a different name, underscoring the persistent stigma of mental illness). The story was widely shared in the UK and not only inspired others to come forward with their own stories, but also led to a book deal and, eventually, to an approach from an agent to appear on a TV show.

"Writing about 'pure OCD' was not a conscious decision, but more like an unstoppable energy," Cartwright says.

Cartwright, like Marnie, was engaging and approachable in the production of Pure. She is very pleased with how it turned out, but notes that the show's story is less explicit than her book. "There are no depictions that hint at pedophilia or violent intrusive thoughts."

"I understand that it may not be appropriate for cinematic entertainment, but it is a kind of censorship of my experience.

Cartwright wrote in a 2013 essay that on a spring night when she was 15, an image of a naked child suddenly popped into her mind and "every corner of (her) world folded in on itself." She tried to erase the image from her mind, but it came back strong again. She tried to make sense of the thought, but could not. 'Am I a pedophile? ' It was a big, pressing question in my adolescence, bigger than the question of whether I was Keanu or Leo."

Cartwright's harrowing soul-searching is, unfortunately, all too common for Pure O people. In his seminal book, The Imp of the Mind, the late Lee Baer, a professor of psychology at Harvard Medical School, wrote that people with pure OCD tend to think the most inappropriate things at the most inappropriate times. Tragically, many adolescents also suffer from these severely bad thoughts, often convinced that they are morally bad people." As children, they learn little about the workings of their own minds at school or at home, which can lead to dangerous misconceptions later in life," he writes.

Cartwright, now 34, has been using cognitive-behavioral therapy and exposure therapy, considered the most effective treatments for OCD, since his diagnosis. Like other anxiety disorders, Pure O will never be completely "cured," but Cartwright feels that she has her illness under control. She later co-founded Made of Millions, a non-profit organization dedicated to changing the world's perception of mental health.

"Activism is at the core of my book and TV show," she says.

"I want to show people that it is possible to be a happy, functional human being and have a career and social life."

Perhaps one of the most important lessons she has learned on her not-so-easy path to understanding Pureo is the power of humor. She adds, "There was a time in my life when I couldn't even imagine laughing at my situation, but laughter is actually therapeutic."

Clive, who plays Marnie in Pure, agrees. If you can laugh at what scares you, it loses a lot of its power," she told Marie Claire of the series' comedic approach. 'Marnie is a hero's journey, and humor is her superpower.'