I've had a bias in this direction for quite a while. When learning about neurodegenerative diseases back in college over a decade ago my conclusion at the time was that something metabolic was going on. Nothing else made sense to me as an explanation for how symptoms and pathology for a disease could show up after 60ish years. At that time I couldn't figure out how to make the link though, so it was a leap.

I was in a lab meeting maybe 4 years ago or so and my PI had just come back from a conference on Alzheimer's. He reported back that groups had started investigating the role of mitochondrial dysfunction in the disease and had been able to find that lineages with variants in genes related to mitochondria and energy homoeostasis were far more likely to have or develop Alzheimer's. I haven't kept an eye on progress in that line of research, but it is in line with what is being reported/speculated here.

Finally, a couple of years ago I ran into the father of someone I went to middle school with and I learned that he was a biochemist. Somehow the conversation wound around to the challenge of understanding neurodegenerative diseases. I asked him for his take on a disease that only presents after 60ish years. His immediate answer was DNA damage during mitosis. But neuron's don't divide. And then it hit me. There IS something that is still dividing inside the neurons! It is the mitochondria! The other possibility is the astrocytes, the microglia, or some other mitotic cell population in the brain, but the mitochondria really stand out as fitting both the fact the neurons don't divide and the instinct from a veteran biochemist that something that takes so long to appear must be related to DNA damage.