What to expect from treatment for Alzheimer’s – 03/04/2024 – Suzana Herculano-Houzel

How do you treat a disease when scientists can’t even agree on what the disease is? Without a precise definition, diagnosing is a difficulty, of course — but treating what is not understood is also complicated. It doesn’t help at all to have to deal with social media bombarding those with the disease in the family with promises of stem cells and other suspiciously miraculous treatments, which only gets worse under the pressure of well-meaning and “connected” friends and relatives. Of course we want to try everything. But as time and money are scarce goods, at some point, we have to say: enough is enough! Where?

The Neuroscientist on Duty comes to help those who are going through this, taking the opportunity to respond to the request of Daniela, my best friend, whose 81-year-old father is in clearly visible decline. My best friend here in the US, a perfectly lucid 86-year-old scientist who comes to work every day, also deals with his 81-year-old wife who now no longer recognizes him. With or without a conclusive definition, Alzheimer’s disease is a growing reality in our society where more and more people reach close to one hundred years of life.

But what you understand about the disease makes all the difference. No, Alzheimer’s is not “memory loss caused by accumulation of amyloid plaques in the brain”; The severity of memory loss is not simply a function of the number of these cards, and, as if that weren’t enough, a lot of people walk around with these cards and without any sign of memory loss. Perhaps “extreme loss of synapses that begins in the hippocampus, the part of the brain responsible for forming new memories, which spreads, worsens, and becomes a loss of brain mass, while recent memory goes with it.” Let’s say that’s it.

With the hippocampus losing its connections, new associations do not enter memory. The questions and jokes are repeated, the glasses are scattered around the house, the daily shower disappears into the black hole that swallows each day’s mental agenda.

Along with the connections in the hippocampus, the most recent memories are also gradually lost, and as a result, the patient’s brain record of their life history is gradually destroyed, starting with the most recent events. Those who follow closely witness the years disappearing. My friend’s wife, who I’ve been visiting regularly for 18 years, doesn’t recognize me anymore — but she still remembers her friends from 30 years ago, when she came to Nashville.

Understanding that Alzheimer’s disease does not block memories, but rather undoes them, is sad but fundamental. There is no hypothetical stem cell that recovers connections formed and honed by each person’s life history; At most, these cells — which would have to be injected directly into the hippocampus — would provide the same help as adding more empty pages to the pad where you make new notes.

The same goes for injections of antibodies that supposedly reduce amyloid plaques in the brain, or, what is actually effective, drugs that amplify synaptic signal transmission. What remains difficult to access memories recorded in existing synapses may still be able to be rescued, but the best hope for treatment is just to stop the disease. To recover lost memories, just living the same life again.

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