A 23-year-old man in the UK is stuck in an ongoing eight-year loop of déjà vu, according to a report published in Journal of Medical Case Reports, and his situation has neuroscientists completely stumped.

The patient, who has a history of anxiety and a family record of obsessive compulsive disorder, started experiencing persistent déjà vu in 2007, after taking LSD during his first year of university. Although some of the episodes only lasted minutes, they could also persist for much longer. The patient told scientists that he felt "trapped in a time loop" and found the experiences "very frightening". He stopped watching TV, listening to the radio, or reading newspapers and magazines, as he felt like the content had been plucked from his memories. As you can imagine, this only made his anxiety worse.

"Rather than simply the unsettling feelings of familiarity which are normally associated with déjà vu, he complained that it felt like he was actually retrieving previous experiences from memory, not just finding them familiar," the authors wrote in the paper, published at the end of last year.

For most of us, déjà vu is short-lived and not overly unsettling. The only people doctors know of who experience the phenomenon more intensely are those with temporal lobe epilepsy, who have abnormal neural firing or seizures in the region. But this young man's brain scans have all come back clear and show no signs of damage, seizures, significant memory impairment or other neurological conditions, leaving neuroscientists stumped.

It only makes it more challenging that medical scientists still don't fully understand what déjà vu is, or what causes it. It's generally believed that it's the result of a temporary neurological error in the processing of incoming information, leading someone believe that they've experienced it before. There is also early research that suggests déjà vu is more common in highly creative achievement, but, up until now, scientists hadn't associated the experience with psychological conditions.

His particular symptoms have led doctors to believe that he has the first recorded instance of déjà vu triggered by anxiety, which they're now calling "psychogenic déjà vu". The researchers explain the study is now cause for further investigation into the link between anxiety and other psychological disorders and déjà vu.

Or maybe theoretical physicist Michio Kaku is right, and déjà vu is actually a symptom of flipping between parallel universes - an idea that we find terrifyingly awesome:

Source: Feel Guide