Study: Brain's Ability to Erase Old Memories May Be Alzheimer's Key

The brain's ability to clear away old memories may be tied to its ability to take on new ones, according to researchers at Princeton University.

Investigators are hopeful that their findings will show them what happens inside the brains of patients with Alzheimer's disease.

Preseniliin-1 (PS1) gene mutations are found in most patients with early-onset Alzheimer's disease. PS1 encodes for a brain cell protein that makes up regions of the brain associated with learning and memory.

Most new brain cells are generated in the hippocampus but this portion of the brain only has a limited number of neurons, so long-term memories normally move from the hippocampus to the outer layer of the brain called the cortex.

When researchers removed PS1 from the brains of mice, they found that the mice were unable to erase memories they no longer needed. They also formed significantly fewer neurons than normal mice, suggesting PS1 has a significant effect on the formation of new nerve cells, according to the study published in the journal Neuron.

Because PS1 is present but altered in most patients with early-onset Alzheimer's disease, researchers speculate that a mutated gene tells the body to either undergo too much neurogenesis and erases memories before they are copied to the cortex, or else too little neurogenesis, causing a failure of the brain to clear our memories that had been copied to the cortex.

Because early-stage Alzheimer's patients show problems forming new long-term memory, it may be a sign of a breakdown of the hippocampus system, said the researchers.

Other sources: Neuron