30th Jan 2017
SOMETHING very odd is happening in the US state of Massachusetts, where more than a dozen people have suddenly and inexplicably lost their memories.
Researchers at the Lahey Hospital & Medical Center in Burlington and the Massachusetts Department of Public Health (MDPH) say they are baffled by an “amnesia cluster” of 14 people.
The patients, aged between 19 and 52, were treated for “striking anterograde amnesia” — an “unusual” form of the syndrome — between 2012 and 2016.
People with this type of amnesia have trouble forming new memories and they often cannot recall events from the immediate past, such as something that has just happened to them, Live Science reported.
Doctors have so far been unable to work out what triggered the syndrome but the 14 patients have certain commonalities which could provide clues.
In their January 27 report, Dr Jed Barash, Dr Nick Sommerville and Dr Alfred DeMaria Jr note that each of them had either tested positive for drugs or had a history of substance abuse.
In nine of the cases, the patients were unconscious when they were brought to the hospital and experienced amnesia when they came to.
The other five individuals had been brought to hospital emergency after family or friends noticed they were experiencing severe memory loss.
Twelve of the patients had a history of using opioid drugs, including prescription painkillers or heroin. Many had also used other drugs, including marijuana, cocaine and amphetamines.
Despite the obvious health risks associated with these substances, they were not typically linked to the onset of anterograde amnesia, the report said.
Significantly, brain scans of all 14 patients revealed an unusual finding: MRI tests showed significantly reduced blood flow to a part of the brain called the hippocampus, which is important for memory formation.
Humans have two hippocampi, one on either side of their brain, and the patients in the report had reduced blood flow to both hippocampi. Sudden amnesia that’s tied to reduced blood flow to both hippocampi is rare, researchers said.
A handful of similar cases have been reported in the past, but these were stand-alones rather than clusters and were tied to exposure to a toxic substance, such as carbon monoxide, the report said.
Investigations are ongoing, with doctors being asked to be on the lookout for more cases to determine whether this new cluster “represents an emerging syndrome related to substance use or other causes” such as exposure to a toxic substance, the report said.