Psychologist JoAnn Deak opened her talk at a recent 92Y event by noting the similarities between chemical mechanisms activated from love and a high from heroin.

“We now know that the chemical changes in parts of the brain when you’re in love are equal to that of heroin doses or high cocaine doses, so you kind of know. If you have to ask if you’re in love, you’re not,” Deak said, to a smattering of chuckles.

Is her statement all that off? Ask poet Jim Carroll—if he weren’t dead he’d likely tell you heroin was his very first love. Or Caroline Knapp, author of Drinking, A Love Story, she’d tell you the same about spirits—but she’s dead, too. It’s one thing for writers to equate their addictions with love or for Shakespeare to call love “merely a madness,” but for scientists to do so is an entirely new spin on the once ephemeral subject.

The chemical changes Deak is referencing are most likely related to the release of dopamine, a neurotransmitter once referred to by neuroscientist Vaughn Bell as the chemical equivalent of Kim Kardashian. We’re supposedly awash in dopamine—it’s released when we eat cupcakes, fire guns, have sex, shoot smack, play roulette, or die on a SoulCycle. Now, it’s being associated with love and addiction.

Dopamine is a naturally occurring chemical released by neurons sent across synapses to other neurons. While this may sound simple, each neuron can communicate with nearly 10,000 other neurons; there are close to 100 billion neurons in the human brain. This leaves us with a network of nearly 1,000 trillion possible connections. That’s more than the number of stars in the Milky Way, jammed into three pounds of tissue floating in your skull. To further complicate this byzantine organ, there are different types of dopamine receptors thought to be responsible for different functions.

Does science back Deak’s claim, that because dopamine is released by drugs and love that they have anything to do with one another? Researchers do, in fact, call love a “natural addiction,” in that we become addicted to our partners and crave them and feel withdrawal when they’re not around.

Biological anthropologist Helen Fisher is a senior researcher at the Kinsey Institute who studies love and addiction. In 2014 she wrote a book chapter called “The Tyranny of Love.” According to her research, fMRI scans “indicate that feelings of intense romantic love engage regions of the brain’s ‘reward system,’” she goes on to write, “specifically dopamine pathways associated with energy, focus, motivation, ecstasy, and craving, including primary regions associated with addiction.”

In an interview with The Daily Beast, Fisher explained what this means. “The reward system is the wanting system. It becomes activated when you fall madly in love.” Romantic love, according to Fisher, is then nothing more than a mating drive, as primordial and necessary for life as thirst and hunger.

Fisher likens love to an addiction, given they both share several of the same brain systems. “If you look at a photo of your sweetheart, you’ll find the area where dopamine is manufactured—the ventral tegmental area—becomes quite active.” Like any addiction, Fisher believes, love can become dysfunctional. “It is my guess that there are more people in jail from various love addictions than there are from heroin addiction.”

While this hypothesis may sound unintuitive, crimes of passion indeed turn dark. “If you’re in love and are rejected, you may kill yourself or somebody else, slip into a clinical depression, [or] maybe start stalking,” she said.

Of course, “love may also be a perfectly wonderful addiction,” Fisher said. It pulls people together, any may result in lifelong commitment or children. And because dopamine is produced organically, Fisher refers to love as a “natural addiction,” unlike external causes of dopamine released from drugs such as cocaine.

But such claims are being questioned by scientists like Dr. Joe Herbert, emeritus professor of neuroscience at Cambridge. He told The Daily Beast, “The role of dopamine in reward has been over-emphasized. That’s not to say,” he added, “that the brain’s dopamine system isn’t closely concerned with those areas responsible for reward, but the idea that any reward is a puff of dopamine is simplistic and untrue.”

“It’s a complicated mix, so love can’t simply be represented by a ‘rush’ of dopamine,” concluded Herbert. “And forgive me saying so, but I think Deak’s take on the brain and love is a bit simplistic.”

Dr. Sally Satel is a psychiatrist and lecturer at Yale University’s School of Medicine, and co-author of Brainwashed—The Seductive Appeal of Mindless Neuroscience. Unlike some of her contemporaries, Satel is critical of generalizing claims coming out of contemporary neuroscience, especially when complex human behaviors and emotions are reduced to neural mechanisms.

“Anything novel or rewarding will get the dopamine system going,” she told The Daily Beast. “That certain areas of the brain are active during the experience of love and addiction is only a single commonality.” What about all of the other systems in play, she wonders.

Similar to her arguments in Brainwashed, Satel pointed out the flaws of interpreting brain scans. “It’s way too facile to infer human subjective experience in much detail from brain scans,” she said. Like Herbert, Satel is not interested in simplistic renderings of complex human experiences. “The very fact that love and cocaine are also subjectively different in so many important ways, simply shows that there’s a hell of lot more to the story than dopamine.”

So maybe matters of love are best left to poets. In the early 1600s, Francois de La Rochefoucauld said, “True love is like ghosts, which everyone talks about and few have seen.” What would Rochefoucauld’s reaction be to scientists who say they’ve seen love?