**Question:** A 67 year old lady is brought in by her 6 children saying that she has gone senile. Six months after her husband's death she has become more religious, spiritual and gives lot of money in donation. She is occupied in too many activities and sleep less. She now believes that she has a goal to change the society. She does not like being brought to the hospital and is argumentative on being questioned on her doings. The diagnosis is -

A. Dementia
B. Depression
C. Alzheimer's disease
D. Parkinson's disease

**Correct Answer:** D. Parkinson's disease

**Core Concept:** Parkinson's disease is a degenerative disorder of the central nervous system that primarily affects the motor system. It is caused by the loss of dopaminergic neurons in the substantia nigra, a region of the midbrain involved in motor control and movement.

**Why the Correct Answer is Right:** The correct answer is Parkinson's disease (option D) because it is characterized by motor symptoms including tremors, rigidity, bradykinesia (slowness of movement), and postural instability. These symptoms are consistent with the patient's presentation of decreased sleep, increased religiosity, and difficulty with motor control.

**Why Each Wrong Option is Incorrect:**

A. Dementia (correct answer) is a general term for cognitive decline, but the specific motor symptoms in this case point more towards Parkinson's disease.
B. Depression (option B) may present with cognitive impairment and mood changes, but the motor symptoms are not typically as prominent as in Parkinson's disease.
C. Alzheimer's disease (option C) is another type of dementia characterized by memory loss and cognitive decline, not the specific motor symptoms seen in this case.

**Clinical Pearl:** Parkinson's disease is a common misdiagnosis of depression due to the shared motor symptoms. It is crucial for medical professionals to consider the presence of motor symptoms in their differential diagnosis when evaluating patients with cognitive and mood changes. Early diagnosis and treatment can significantly improve the patient's quality of life and slow disease progression.