Lithium is not commonly used for the treatment of Alzheimer's disease.

Donepezil inhibits acetylcholinesterase, thereby increasing the levels of acetylcholine in the brain.

Donepezil can cause nausea, vomiting, and diarrhea as side effects.

Rivastigmine inhibits acetylcholinesterase, thereby increasing the levels of acetylcholine in the brain.

Rivastigmine can cause nausea, vomiting, and diarrhea as side effects.

Memantine blocks NMDA receptors, thereby reducing excitotoxicity and neuronal damage.

Memantine can cause headache, dizziness, and confusion as side effects.

Parkinson's disease is a neurodegenerative disorder, but it is not a type of dementia.

Alzheimer's disease is the most common type of dementia, accounting for approximately 60-80% of cases.

Vascular dementia is the second most common type of dementia, accounting for approximately 10-20% of cases.

Lewy body dementia is the third most common type of dementia, accounting for approximately 5-10% of cases.

Frontotemporal dementia is the fourth most common type of dementia, accounting for approximately 5-10% of cases.

Parkinson's disease dementia is the fifth most common type of dementia, accounting for approximately 2-5% of cases.

Stroke is the most common cause of vascular dementia, accounting for approximately 80% of cases.

Alpha-synuclein aggregation is the most common cause of Lewy body dementia.