A cluster of cases of amnesia with no clear cause puzzled researchers. Fourteen cases of sudden severe amnesia without clear medical explanation was reported from Massachusetts from 2012 to 2016. The only link in the patients is their history of drug use. There is no previous association of amnesia to drug use.
The patients range from ages 19 to 52. No clear etiology or cause was found at the time of initial evaluation and they were reported as rare, isolated cases. However, researchers revealed that 13 out of 14 patients tested positive for drug abuse or had recorded history of drug use for medical purposes. Eight were found positive for opioids, two for cocaine, and two for benzodiazepines.
The patients were diagnosed of anterograde amnesia, which influences patient's ability to create memories. It eventually leads to partial memory loss or inability to recall recent events. Meanwhile, memories from before remain intact. Live Science reported that some of the patients were brought unconscious in the hospital and had amnesia after regaining consciousness while others were brought conscious to the hospital after family members notice they were experiencing memory loss.
In a paper published in the journal Morbidity and Mortality Weekly Report by the CDC on Friday, Jan. 27, researchers revealed unusual findings in the MRI scans of the patients. According to the tests, the blood flow on the part of the brain called the hippocampus was significantly reduced. The hippocampus is related to memory formation.
The researchers highlighted that a broader study is needed to determine if this incident could represent a new emerging syndrome related to drug use or introduction of a toxic substances. They added that doctors should consider doing an MRI and drug screening for patients who experience sudden amnesia. Among the reported cases, two of the patients continued experiencing memory problems after more than one year.
