Alzheimer’s: We might soon be able to recover lost memories

A potentially groundbreaking study has shown that – in mice at least – memories thought lost to Alzheimer’s may not be gone forever.

The research comes from 1987 Nobel Prize winner Susumu Tonegawa and his team, who discovered that stimulating certain areas of mouse brains with blue light could force the rodents to recall memories previously assumed lost.

In other words: patients with Alzheimer’s may not have lost their memories, just the ability to access them. That may seem like pointless semantics, but it’s a serious difference, potentially paving the way to a cure in the long run.

“As humans and mice tend to have a common principle in terms of memory, our findings suggest that Alzheimer’s disease patients, at least in their early stages, may also keep memories in their brains, which means there may be a possibility of a cure,” Tonegawa told AFP.

So how do you know when a mouse has forgotten something? With a little bit of Pavlovian training. A group of mice – some healthy, and some genetically modified to exhibit Alzheimer’s-like symptoms – were put in a box with a low-level electrical current passing through the floor.

The healthy mice would freeze in fear when returned to the box after a 24-hour break, while those with Alzheimer’s would behave without fear, suggesting they have no memory of the past experience.

However, these forgetful mice would exhibit the same reaction as the healthy ones when the engram cells of the brain were targeted with blue light, recalling the experience in the same way healthy mice seemed to.

Okay, so the mice got their memory back, but why? Well, the researchers noticed that the forgetful mice had physically different brains to the healthy ones with fewer dendritic spines, which are responsible for forming synaptic connections with neighbouring cells. Light stimulation increased the number of spines to similar levels found in normal mice – at which point they behaved in the same manner.

So Alzheimer’s is cured then? Not so fast – this is only in mice, and it’s only in early-stage Alzheimer’s for now – but it’s certainly a promising discovery. “Early-stage Alzheimer’s may be cured in the future should a new technology that meets ethical and safety conditions for treating humans be developed,” said Tonegawa.

The full research is published in Nature.

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Images: Global Panorama and deandare06 used under Creative Commons