A recent nature publication demonstrated fungal material in the forebrain and hindbrain regions of an alzheimer patient’s brain.
This story reminds me of that brilliant story of Dr. Barry Marshall. Dr. Marshall won the Nobel prize for medicine in 2005 for establishing the cause of stomach ulcers. Before his discovery, stomach ulcers were attributed to spicy food, stress and a poor lifestyle. The discovery established that ulcers were caused by bacterial infection - thus ensuring that antibiotics were a solid cure for stomach ulcers.
A pretty interesting anecdote - the test subject for the experiment was Dr. Marshall himself. He downed some of the bacteria in question and developed symptoms rapidly - contrary to an expected long-term development of symptoms.