Recency effects in HIV-associated dementia are characterized by deficient encoding

Area of Science:

• Neuropsychology
• Cognitive Neuroscience
• Infectious Disease Research

Background:

• HIV-associated dementia (HAD) is a neurocognitive disorder affecting individuals with HIV.
• Understanding the specific cognitive mechanisms underlying HAD is crucial for diagnosis and treatment.
• Serial position effects in learning are well-documented but less understood in the context of HAD.

Purpose of the Study:

• To investigate the nature of serial position learning effects in individuals with HAD.
• To explore the cognitive mechanisms contributing to these effects.
• To compare learning patterns in HAD with HIV-positive and HIV-negative control groups.

Main Methods:

• Participants included 16 individuals with HAD, 50 HIV-positive non-demented individuals, and 50 HIV-seronegative controls.
• The Hopkins Verbal Learning Test-Revised was used to assess learning and memory across serial positions.
• Recognition testing was employed to differentiate encoding from retrieval deficits.

Main Results:

• HAD participants showed reduced recall in the middle serial position and increased recall in the recency region compared to controls.
• No significant primacy effect was observed in the HAD group.
• Impairments in discriminating targets from distractors were noted across all serial positions in the HAD group during recognition testing.

Conclusions:

• HAD is associated with altered serial position learning, characterized by reliance on recency and reduced middle recall.
• The findings suggest a primary encoding deficit rather than a retrieval impairment in HAD.
• These results highlight specific cognitive challenges in HAD, potentially related to auditory attention span and encoding strategies.