**Core Concept**
Frontotemporal dementia (FTD) is a group of neurodegenerative disorders characterized by progressive damage to the frontal and temporal lobes of the brain. This leads to cognitive, behavioral, and emotional changes that can significantly impact an individual's quality of life. FTD is often misdiagnosed as Alzheimer's disease due to its similar presentation, but it has distinct clinical features.

**Why the Correct Answer is Right**
The patient's symptoms, such as difficulty with organizing finances and paying bills, withdrawal from social interactions, and inappropriate behavior, are classic features of frontotemporal dementia. The MMSE score of 23 indicates mild cognitive impairment, which is consistent with FTD. Furthermore, the patient's indifference to his wife's concerns and denial of any problems are also characteristic of FTD. The family history of Alzheimer's disease may have led to a delayed diagnosis of FTD. The patient's medical history of hypertension and type 2 diabetes mellitus does not directly contribute to the cognitive decline in this case.

**Why Each Wrong Option is Incorrect**
**Option A:** Alzheimer disease typically presents with memory loss, disorientation, and difficulty with word-finding, which were not prominently featured in this patient's history. While Alzheimer's disease can also cause behavioral changes, the patient's lack of concern and denial of problems are more characteristic of FTD.

**Option B:** Creutzfeldt-Jakob disease is a rapidly progressive dementia that typically presents with rapid cognitive decline, myoclonus, and visual disturbances. The patient's slow progression and lack of these distinctive features make Creutzfeldt-Jakob disease an unlikely diagnosis.

**Option C:** Dementia with Lewy bodies is characterized by fluctuating cognition, visual hallucinations, and parkinsonian features. While the patient's cognitive decline is slow, there is no mention of visual hallucinations or parkinsonian symptoms, making this diagnosis less likely.

**Clinical Pearl / High-Yield Fact**
Frontotemporal dementia often presents with significant behavioral changes, such as apathy, disinhibition, or aggression, which can be misattributed to other conditions. A thorough evaluation of the patient's behavior and cognition is essential for an accurate diagnosis.

**✓ Correct Answer: D. Frontotemporal dementia**