Over the course of five years in eastern Massachusetts, a group of 14 people suddenly stopped remembering things in what health officials are calling a small but puzzling cluster of amnesia.
While the cause of the serial memory loss remains unknown, researchers found one characteristic linking the seemingly random cases – a history of substance abuse.
Of the 14 amnesia cases from 2012 to 2016, which occurred in the region surrounding greater Boston and included a toxicology test at the time of assessment, eight of the patients tested positive for opioids and four others for either cocaine or benzodiazepines use, according to medical professionals reporting in the Centers for Disease Control and Prevention’s (CDC) national disease trends.
The link between amnesia and substance abuse has officials wary that an unknown cause is behind the episodes of memory loss.
“What we’re concerned about is maybe a contaminant or something else added to the drug might be triggering this,” corresponding author Dr. Alfred DeMaria, state epidemiologist at the Massachusetts Department of Public Health (MDPH), told Stat. “Traditionally there’s no evidence that the drugs themselves can do this.”
The memory-loss mystery is leaving health officials on edge. “Considering 14 cases in four years, we’re worried we’re going to find more cases,” DeMaria told Stat.
Findings of Impaired Memory
The initial pieces of the medical mystery came together after a neurologist in Boston reported four cases of an “uncommon amnestic syndrome” to the Massachusetts Department of Public Health in November, 2015. Shortly thereafter, an email alert went out to neurologists and other specialty physicians asking about similar cases, and soon 10 additional cases were identified.
After reviewing case files, researchers noted that the 14 patients bore differences in details, history, age and home location. One patient, for example, resided in New Hampshire, and a second patient was visiting from the state of Washington. Yet all 14 patients were evaluated in Boston-area hospitals.
Other details were a mix of similar and dissimilar parts. Of the 14 total patients, nine were unconscious when they came under medical attention. The state of unconsciousness soon gave way to significant memory loss. “After regaining consciousness, all nine were noted to be amnestic,” states the CDC report.
For the other five patients, friends or family “observed the emergence of severe memory loss” following medical intervention and subsequently returned the patients to the hospital for more tests.
Yet all patients showed the same markers of memory loss, including significant damage to the hippocampus, a region of the brain instrumental in creating and storing memories. Specifically, the patients suffered a “bilateral ischemia of the hippocampus,” which at least one previous study has noted is extremely rare.
“The combination of clinical findings described in this report has previously been reported rarely and in isolation,” state the researchers, who believe their findings, although representing a pattern of small proportions, necessitate further evaluation.
“Further case identification and reporting are needed to determine whether these combined observations represent an emerging syndrome related to substance use or other causes (e.g., a toxic exposure),” write the researchers.
They also note that “advanced laboratory testing, including testing for synthetic opioids (e.g., fentanyl) and their analogues, as well as extraneous substances not assessed in these reported cases, might further clarify an association with substance use.”