The average age for cataract surgery is approximately 73 to 75 years old. But cataracts can occur in the 30s, 40s, and 50s. Of course the older the patient gets the more common the cataracts.
Two neurotransmitters seem to play a role in Alzheimer's Disease: acetylcholine and glutamate. Acetylcholine (ACh) activates muscles and helps with arousal, short-term memory, and learning. Individuals with AD have low levels of ACh.
There is tentative evidence that exposure to air pollution may be a contributing factor to the development of Alzheimer's disease. An infection with Spirochetes (a bacterium) in gum disease may cause dementia and may be involved in the pathogenesis of Alzheimer's disease.