Cognitive Performance and Variability in Adults: A Study Overview

This study investigates cognitive performance and variability in adults, focusing on two distinct age groups: a general adult sample and an older adult sample, including those with mild cognitive impairment (MCI). A total of 394 participants aged 20 to 79 years were recruited through Prolific, an online research platform, while 94 older adults aged 50 and above were sourced from The University of Texas at Dallas, UC San Diego, and the University of Miami Miller School of Medicine. All participants provided informed consent, and their data were anonymized during collection.

Nature

Participants engaged in a series of mobile cognitive tests (EMCTs) and ecological momentary assessment (EMA) surveys. The general adult sample completed eight EMCTs over ten days, focusing on various cognitive functions such as memory and processing speed. Each session lasted 8–10 minutes, and participants rated their negative affect and substance use during EMA surveys. In total, 375 participants from this group were included in the final analysis after excluding those with invalid performance due to substance use or insufficient test completions.

Nature

The older adult sample followed a similar protocol, participating in EMCTs and EMA surveys over 30 consecutive days. This group was assessed for cognitive performance using traditional neuropsychological measures, including the Montreal Cognitive Assessment (MoCA) and various memory tests. The study aimed to determine if findings from the general adult sample could be replicated in a clinically relevant population.

Nature

The EMCTs for both age groups included tasks designed to measure different cognitive abilities. For instance, the Memory List task assessed recognition memory, while the Memory Matrix evaluated visual working memory. Performance metrics were standardized using T-scores, allowing for comparisons across tasks. In the older adult sample, additional EMCTs were introduced, such as the Color Trick, which tested inhibition and processing speed.

Nature

The study calculated intra-individual variability (IIV) in cognitive performance across both samples. IIV was assessed through various statistical methods, including root mean square of successive differences and standard deviation from valid administrations. The analysis also explored the relationship between IIV, average negative affect, and demographic factors such as age and education.

Nature

The research was conducted under the approval of institutional review boards at the respective universities, ensuring ethical standards were met. The study's methodology was designed to adapt to COVID-19 restrictions, with both in-person and remote assessments utilized.

Nature

While the study's methodology is robust, some critics may argue that the reliance on self-reported data for substance use and affect could introduce bias. Additionally, the exclusion criteria may limit the generalizability of findings to broader populations, particularly those with more severe cognitive impairments.

Nature

• “This study received exempt status approval from the UC San Diego Institutional Review Board (IRB).” — UC San Diego IRB

Nature

• “Participants completed a baseline assessment to gather sociodemographic information and neuropsychological testing.” — Research Team

Nature

• “If participants reported any alcohol or cannabis use in the past two hours or four or more drinks at any time that day, then EMCT trials were considered invalid for that day.” — Research Protocol

Nature

This study provides valuable insights into cognitive performance and variability among adults, highlighting the importance of both age and cognitive status in understanding cognitive function. The findings may inform future research and interventions aimed at enhancing cognitive health across the lifespan.

Nature