**Core Concept**
Dementia of Alzheimer's type (DAT) is a neurodegenerative disorder characterized by progressive cognitive decline, memory loss, and impairment of daily functioning. The pathophysiology involves the accumulation of amyloid-beta plaques and tau protein tangles in the brain, leading to neuronal damage and death.

**Why the Correct Answer is Right**
DAT is associated with the loss of cholinergic neurons in the basal forebrain, particularly in the nucleus basalis of Meynert. This leads to a reduction in acetylcholine levels, a neurotransmitter crucial for memory and cognitive functions. The cholinergic hypothesis of DAT suggests that the decline in cholinergic neurotransmission contributes to the cognitive symptoms of the disease. **Option C: Loss of dopamine-producing neurons** is incorrect because DAT is primarily associated with the loss of cholinergic neurons, not dopaminergic neurons.

**Why Each Wrong Option is Incorrect**
* **Option A:** Accumulation of amyloid-beta plaques is a hallmark of DAT, making this option incorrect.
* **Option B:** Neurofibrillary tangles composed of tau protein are another characteristic feature of DAT, so this option is also incorrect.
* **Option D:** The hippocampus is a brain region that is severely affected in DAT, leading to memory loss and spatial disorientation, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
The cholinesterase inhibitors, such as donepezil, rivastigmine, and galantamine, are used in the treatment of DAT to increase acetylcholine levels by inhibiting the enzyme acetylcholinesterase.

**Correct Answer:** D.