Helping Alzheimer's Patients Bring Back Memories

In Scientific American , Dheeraj Roy, a McGovern Fellow in the Stanley Center for Psychiatric Research at the Broad Institute of the Massachusetts Institute of Technology and Harvard University, writes that the scientific community may be closer to understanding why people with dementia-causing diseases suffer memory loss. Difficulty recalling recent events is a hallmark of early Alzheimer's, often attributed to either an inability to correctly store new information in the brain, or a weakened ability to remember stored information. Roy says a 2016 study in Nature focused on both memory storage and memory recall processes in an animal model of early Alzheimer's. "I developed an approach that allowed us to activate the neurons that store memory information, referred to as memory engrams, through optogenetics — that is, introducing a gene that is light sensitive into the memory engram cells of 'Alzheimer's' mice, then delivering blue light pulses to activate them — and measuring memory recall strength directly," he explains. Surprisingly, there were comparable concentrations of engram cells in normal healthy animals and Alzheimer's animals, implying that the initial memory storage process is preserved. "Targeting the recall process in Alzheimer's animals led to an improvement in their memory, which reached the performance level of normal animals," Roy says. A later study in PNAS confirmed the existence of a similar memory recall problem in another animal model of amnesia. Roy says these two studies clearly illustrate that "we need to take advantage of targeting recall to help treat patients in the near future."