Which of the following is NOT an effect of HIV on the central nervous system?

Increased synaptic plasticity is not an effect of HIV on the central nervous system. HIV primarily has deleterious effects on brain function, leading to conditions such as encephalopathy, dementia, and peripheral neuropathy.

Encephalopathy refers to a range of brain dysfunctions that can occur in HIV infection, characterized by cognitive decline, altered consciousness, and neurological deficits. Dementia is a severe outcome of HIV infection affecting cognitive functions, leading to significant impairments in memory, problem-solving, language, and daily functioning. Peripheral neuropathy, which can occur due to HIV or its treatments, affects the nerves outside of the brain and spinal cord, causing pain, weakness, and numbness, particularly in the limbs.

In contrast, increased synaptic plasticity refers to the ability of synapses to strengthen or weaken over time, which underlies learning and memory. This process is generally considered a positive outcome for cognitive functioning, something that is severely compromised in individuals affected by HIV. Therefore, this option stands out as not aligning with the detrimental impacts HIV has on neurological health.