Reversible dementia causes are all except-
**Core Concept**
Reversible dementia refers to a condition where cognitive decline is potentially reversible with treatment or removal of an underlying cause. This type of dementia is often caused by identifiable and treatable conditions, such as medication side effects, infections, nutritional deficiencies, or metabolic disorders.
**Why the Correct Answer is Right**
Reversible dementia can be caused by various factors, including **normal pressure hydrocephalus (NPH)**, which is a condition characterized by the accumulation of cerebrospinal fluid in the brain's ventricles, leading to cognitive decline and gait disturbances. Other causes of reversible dementia include **subdural hematoma**, which is a collection of blood outside the brain's blood vessels, and **hypothyroidism**, a condition where the thyroid gland does not produce enough thyroid hormones.
**Why Each Wrong Option is Incorrect**
**Option A:** **Vitamin B12 deficiency** is a cause of reversible dementia, as it can lead to cognitive decline and neurological symptoms if left untreated. Therefore, this option is incorrect.
**Option B:** **Alzheimer's disease** is a progressive and irreversible form of dementia, making this option incorrect.
**Option C:** **Normal pressure hydrocephalus (NPH)** is a cause of reversible dementia, as treatment with shunting or other interventions can improve symptoms.
**Clinical Pearl / High-Yield Fact**
It is essential for physicians to consider reversible causes of dementia in patients presenting with cognitive decline, as timely diagnosis and treatment can significantly improve outcomes.
**Correct Answer: B. Alzheimer's disease.**