It’s one of the first symptoms when diagnosing depression: “Loss of interest or pleasure in activities once enjoyed.”

Psychologists call it anhedonia, from Greek roots meaning “without pleasure.” (It’s the opposite of “hedonism,” the pursuit of pleasure.) You may not be familiar with the term (unless you’re a big Annie Hall fan – it was the film’s original title), but anhedonia is one of two core features, alongside persistent low mood, in depression’s long list of symptoms. It’s also one of the hardest to treat, and a significant risk factor for battling lifelong depression.

But new research offers encouragement. Scientists are uncovering anhedonia’s little-understood causes, opening doors to new treatments like exploring the meaning of life during therapy or identifying brain biomarkers that predict the most effective medications. Though the symptom is notoriously stubborn, really tuning into your anhedonia can set you on a path to overcoming it, experts say – and lessen the chances that depression will recur. “We see it all the time in our clinics, where patients are significantly struggling with the lack of motivation and the lack of experiencing pleasurable activities that they used to enjoy,” said Majd Al-Soleiti, MD, a resident psychiatrist at the Mayo Clinic in Rochester, Minnesota, and author of a recent anhedonia study review. “So it’s a clinical problem, but also we have gained a lot of knowledge in terms of how it may explain so many problems that we have that go beyond depression.”

Anhedonia shows up in a broad range of health conditions, including substance use disorders, eating disorders, and neurodegenerative diseases like Alzheimer’s and Parkinson’s. An estimated 35% of people with epilepsy have anhedonia, plus nearly 20% of people who’ve had strokes, and 25% of those with chronic pain. Among depression patients, up to 70% have anhedonia.

We’ve all learned to tolerate a lack of pleasure in certain situations, like traffic jams and toddler tantrums. Anhedonia is different – it persists, and it’s the result of the brain’s reward processing circuitry malfunctioning. “People need to take anhedonia very seriously because it can have very negative consequences,” including a heightened risk of suicide, said Diego Pizzagalli, PhD, an anhedonia expert and founding director of the Noel Drury, MD, Institute for Translational Depression Discoveries at the University of California, Irvine.