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.
Alzheimer's disease is the most common cause of dementia affecting older people, and is associated with loss of cholinergic neurons in parts of the brain. Acetylcholinesterase inhibitors, such as donepezil, delay the breakdown of acetylcholine released into synaptic clefts and so enhance cholinergic neurotransmission.