Neurosurgery and Brain Health What Is Déjà Vu? Harmless Sensation or Neurological Problem? By Neurosurgery, June 22, 2018 Déjà vu is that feeling of already having experienced a particular situation. While it feels familiar, you doubt the feeling is accurate. In French, déjà vu means “already seen” and many people have experienced it. But what causes déjà vu and why does it happen? Just experiencing déjà vu isn’t usually a problem in itself. But if it’s happening frequently or is a change from past experience, it’s worth getting a neurological evaluation. To learn more about UPMC’s expert epilepsy care, contact UPMC Comprehensive Epilepsy Center. What Causes Déjà Vu? Researchers don’t fully understand the neuroscience of déjà vu, as it’s difficult to replicate in a laboratory or research environment. One theory is that a person may feel this sensation when they see or do something similar to a previous experience that they can’t recall. A study by the University of St. Andrews found that déjà vu is associated with the conflict monitoring and resolution part of the brain, not the memory part. While studying the neuroscience of déjà vu, researchers theorize that the sensation might be a way for the brain to detect memory conflicts. The Neuroscience of Déjà Vu But déjà vu may signal a neurological problem. Someone can have epileptic seizures including temporal lobe seizures, with the only sign or symptom being a feeling of déjà vu. Some older adults with dementia experience chronic déjà vu as a symptom. If déjà vu occurs frequently and you’re concerned about the cause, here are a few questions to consider: Does your déjà vu occur at least a few times each month? Do you have other symptoms after experiencing déjà vu, such as losing consciousness, feeling your heart race, unconscious chewing, or fumbling? Do you visualize abnormal scenes or have strange memories that feel like dreams during déjà vu? If the answer to any of these is yes, talk to your doctor as there may be a neurological issue that should be evaluated. Just experiencing déjà vu isn’t usually a problem in itself. But if it’s happening frequently or is a change from past experience, it’s worth getting a neurological evaluation from your doctor.