What causes dementia?

Dementia is primarily caused by the gradual deterioration of cognitive function due to various underlying conditions, including diseases, injuries, or the effects of substances like alcohol. This decline in cognitive abilities can impact memory, thinking, and the ability to perform everyday activities.

The correct choice emphasizes that dementia is not simply a temporary issue or a reaction to stress but a more persistent and progressive condition brought on by specific health-related factors. Diseases such as Alzheimer's, vascular dementia, and others directly lead to brain changes that result in this mental decline.

In contrast, the other options suggest conditions that either do not lead to the long-term changes associated with dementia or are responses to external stimuli rather than intrinsic brain pathology. Temporary mental confusion might be caused by various factors but does not reflect the chronic nature of dementia. Acute stress, while it can affect cognitive function, does not typically result in the lasting cognitive decline seen in dementia. Additionally, external changes in environment might impact mood or behavior but are not causal factors for the progressive decline in mental function characteristic of dementia.