Which combination drug is known for showing improved mental functioning and activities of daily living performance in patients with dementia?

The combination of Donepezil and Memantine is particularly notable in the management of dementia because both medications target different aspects of the cognitive decline associated with this condition. Donepezil is an acetylcholinesterase inhibitor that works by increasing the levels of acetylcholine in the brain, which is often diminished in patients with Alzheimer's disease. This can lead to improvements in memory, language, and some cognitive functions.

On the other hand, Memantine is an NMDA receptor antagonist that helps to regulate the activity of glutamate, a neurotransmitter that, in excess, can lead to neuronal death and cognitive decline. Together, Donepezil and Memantine can provide a synergistic effect, enhancing cognitive functioning and improving performance in daily living activities beyond what either medication could achieve alone. This combination has been shown to be associated with a modest improvement in symptoms in some patients, particularly those with moderate to severe Alzheimer's disease.

While other combinations listed may have mechanisms that address certain symptoms of dementia or other co-occurring conditions, they do not have the established evidence supporting improved functioning in both cognition and daily living activities to the same extent as Donepezil and Memantine.