Robert D. Moir, a Harvard scientist whose radical theories of the brain plaques in Alzheimer’s defied conventional views of the disease, but whose research ultimately led to important proposals for how to treat it, died on Friday at a hospice in Milton, Mass. He was 58.

His wife, Julie Alperen, said the cause was glioblastoma, a type of brain cancer.

Dr. Moir, who grew up on a farm in Donnybrook, a small town in Western Australia, had a track record for confounding expectations. He did not learn to read or write until he was nearly 12; Ms. Alperen said he had told her that the teacher at his one-room schoolhouse was “a demented nun.” Yet, she said, he also knew from age 7 that he wanted to be a scientist.

Dr. Moir succeeded in becoming a researcher who was modest and careful, said his Ph.D. adviser, Dr. Colin Masters, a neuropathologist at the University of Melbourne. So Dr. Masters was surprised when Dr. Moir began publishing papers proposing an iconoclastic rethinking of the pathology of Alzheimer’s disease.

Dr. Moir’s hypothesis “was and is a really novel and controversial idea that he alone developed,” Dr. Masters said.