Our mind has a sick sense of humor. It turns out that as we lose our memory, and sink into the darkness of dementia, the last memories to disappear are the memories we spent our lives trying to repress. So the final thing that you know is what you've been trying to forget:
For more than half a century, Rachel Kane kept the memories at bay.
There were her daughters to think of, twins born in a displaced persons camp in the aftermath of the second World War. Kane didn't want to burden them with tales of the Holocaust, of a husband shot to death by the Nazis, a baby who starved to death in the forest, an extended family wiped out in a mass execution.
She didn't explain the nightmares that woke her, screaming, in the long string of cramped apartments the family called home after resettling in Detroit and then Los Angeles.
Instead, the university-educated Hebrew teacher who spoke seven languages regaled her daughters with stories about her "beautiful life" before Hitler's armies stormed Poland, successfully locking the war years away until 1998.
That was when her second husband died. When she began to lose her battle with dementia. When she became convinced that the soldiers were coming for her, as they'd done so many years before.
Lying in her room at the Los Angeles Jewish Home for the Aging in Reseda, the elderly woman with the soft white hair and bright blue eyes "was seeing Nazis," recounted daughter Esther Kane Meyers. "She was hearing things. I came and sat with her every day. It was the most painful thing I'd ever seen. It was all happening, right there."
Watching 50 years of strength crumble under the weight of a long-buried trauma made Kane's family sad and angry. What they did not know at the time was that her experience was not uncommon among aging victims of Nazi brutality.
On a somewhat related note, there's recently been a fascinating new paper exploring the link between known Alzheimer genes and improved memory performance. In other words, the same bit of DNA that devastates the brain in old age might actually have a practical purpose. Here's Mindhacks:
The research team, led by neuroscientist Christian Mondadori, looked at the genetics and memory performance of 340 volunteers, all in their early 20s.
The team were particularly interested in which version or allele of the apolipoprotein E (ApoE) gene each person had, because the 'Epsilon 4' allele raises the risk for Alzheimer's disease in old age.
In fact, people with two 'Epsilon 4' alleles are virtually guaranteed to the brain disorder by the age of 80.
Each person took part in a word learning test that involved both short-term and long-term memory. This type of test is known to particularly rely on the function of the hippocampus, a key memory area which is known to decline in Alzheimer's disease.
People who were carriers of the Epsilon 4 allele performed better in the long-term memory test, and no different for short-term memory.
Epsilon 4 looks like a classic example of antagonistic pleiotropy contributing to the evolution of senescence: to natural selection, a small benefit when young is worth paying a massive cost when old.