Which of the following disorders includes cognitive dysfunction as a feature?

Cognitive dysfunction is a hallmark feature of dementia, which is characterized by a decline in cognitive abilities such as memory, reasoning, and problem-solving. In dementia, these cognitive deficits are severe enough to interfere with daily functioning and social interactions. The progressive nature of dementia leads to significant impairments in cognitive functioning, making it distinct in this context.

While other disorders listed, such as depression, generalized anxiety disorder, and bipolar disorder, can include cognitive symptoms, they do not primarily present with cognitive dysfunction as a defining feature. In depression, cognitive impairments like difficulty concentrating can occur but are often secondary to the mood aspects. Generalized anxiety disorder can also involve cognitive difficulties, primarily related to excessive worry and anxiety, but again, this is not a core feature of the disorder. In bipolar disorder, cognitive changes can occur during mood episodes, but the disorder is primarily characterized by mood disturbances. Thus, dementia is uniquely defined by its cognitive dysfunction, which is why it is the most accurate choice among the given options.