BALTIMORE—Researchers at Johns Hopkins University published a new study this week on the cognitive effects of Alzheimer’s disease and other deteriorative brain disorders, finding conclusive evidence that dementia sufferers’ fondest memories are nearly always the first to go.
The five-year study, which followed a group of nearly 3,000 individuals diagnosed with dementia, found that as neurons and dendritic connections in the cerebral cortex are degraded by the disease, patients’ most positive recollections—such as falling in love for the first time or the overwhelming, indescribable joy of holding one’s firstborn child just moments after their birth—are eradicated much more rapidly than other types of memories.
“It appears that the accumulation of abnormal proteins in the brain, which underlies most forms of dementia, first affects the specific memory centers responsible for retaining the subject’s most treasured reminiscences,” said neurologist David Trapp, who noted that during the earliest stages of the disease, patients typically lose all recollection of their most prized personal and professional successes in life. “At acute risk are memories along the lines of the heart-stopping exhilaration of that first kiss at summer camp those many years ago, as the sun slowly set out over the lake and caught the water in just such a way, almost like the lake was on fire. In fact, that type of memory is erased almost immediately.”
“The moment you notice the first signs of dementia in a loved one, you can be certain that the majority of memories that give them any feeling of pleasure, pride, or personal fulfillment have already been forever expunged from their mind.”
“And memory loss progresses quickly from there,” Trapp continued. “The moment you notice the first signs of dementia in a loved one, you can be certain that the majority of memories that give them any feeling of pleasure, pride, or personal fulfillment have already been forever expunged from their mind.”
Trapp added that the happier and more life-affirming a particular memory is, the faster it will be claimed by the neuropathology of dementia. Remembrances of proudly walking through the front door of one’s newly purchased home or of triumphantly marching down the Champs-Élysées with the knowledge of having helped defeat the greatest evil the world has ever known are typically lost within a few weeks of being diagnosed with the condition.
According to the study, brain regions associated with memories of love, smiling, accomplishment, unmitigated joy, comfort, interpersonal tenderness, physical pleasure, beloved childhood pets, and self-respect appeared to be the first targeted by memory-destroying neural plaques.
“In fact, just the act of trying to recall the brightest days of one’s youth—to recapture some small sense of the profound satisfaction that came from learning and discovering and experiencing new things, of the very essence of what is good about being alive—greatly accelerates the process,” Trapp said. “We found that the more subjects attempted to think back to their carefree college years or their childhood escapades with friends over summer breaks, the faster these memories vanished, never to be recalled again.”
In addition to decimating those memories most important and sustaining to the patient, the degenerative effects of dementia seemed to spare the vast majority of the humiliating and unhappy moments from its victims’ lives, the study found, leaving them fully intact as the remainder of one’s store of memories steadily deteriorated and disappeared.
“Even after subjects were robbed of their ability to recognize loved ones and the basic skills necessary to feed and clean themselves, the worst of their memories persisted,” said Dr. Emily Braun, a neurobiologist at Columbia University who contributed to the study. “Functional magnetic resonance imaging shows that areas of the brain that retain, for example, the memory of walking in on one’s oldest and most trusted friend engaged in passionate intercourse with one’s wife or of suddenly being stricken with uncontrollable diarrhea while giving a presentation at a sales conference continue to light up well after the other cortical regions have gone silent.”
“And with complex emotional imprints, such as those stemming from a long relationship with one’s spouse or children, it seems dementia selectively destroys neural circuitry related to the positive aspects of the memories in question, leaving behind only the trauma, pain, and disappointment related to these experiences,” Braun added. “Although more research is necessary, it appears as though the most awful recollections actually become crisper and more vivid to the patient as the disease advances.”
As dementia reaches its terminal stages, Braun confirmed that bitter and displeasing recollections begin to erode as well, eventually leaving each individual with only a solitary, recursive synaptic pathway comprising their single most negative memory. This instance is said to be relived in a perpetual loop, to the exclusion of all other high-level cognitive functioning.
“In their final months, it seems that dementia patients are left with just one exceedingly agonizing memory and nothing else,” Braun said. “In their mind’s eye, the very worst moment of their entire life is the last thing they’ll ever see.”