Imagine your brain as a library of memories, filled with books that preserve moments from your life. But what if those books started to fade away faster than usual? That’s exactly what researchers have found in middle-age and older adults with autism spectrum disorder (ASD). A recent study examined how visual memory abilities change over time in adults with ASD compared to neurotypical adults. The results showed that adults with ASD experienced faster declines in long-term visual memory, while short-term memory remained stable. This decline may be related to differences in the size and connectivity of a key brain region called the hippocampus. Interestingly, a specific metric called hippocampal free-water was found to correlate with changes in long-term visual memory. This metric, measured through MRI scans, could potentially be used as a predictor of cognitive decline in adults with ASD. These exciting preliminary findings shed light on the unique challenges faced by individuals with ASD as they age and open doors for future research on cognitive aging. To learn more about this groundbreaking study and its implications, dive into the full research article!

Research aimed at understanding cognitive and brain aging in adults with autism spectrum disorder (ASD) is growing, but critical longitudinal work is scant. Adults with ASD struggle with tasks involving visual memory compared with neurotypical adults (NT). This may be related to differences in size or integrity of the hippocampus and its’ primary structural connectivity pathway, the fornix. The aim of this study was to describe preliminary findings of longitudinal aging trajectories in short- and long-term visual memory abilities in middle-age and older adults with ASD, compared with matched NT adults. We then evaluated baseline multi-modal imaging metrics of the hippocampal system, including the relatively novel metric of free-water, as potential correlates of longitudinal memory change in the ASD group. Middle-age and older adults with ASD (n = 25) and matched NT adults (n = 25) between the ages of 40 and 70 years were followed longitudinally at ~2-year intervals (range 2–5 years). Participants completed the Wechsler Memory Scale III Visual Reproduction task. Longitudinal mixed models were utilized to detect group differences in memory change with baseline age and sex as covariates. Hippocampal volume was measured via T1-weighted MRI images with FreeSurfer. Fornix fractional anisotropy and hippocampal and fornix free-water were measured from diffusion tensor imaging scans. Exploratory correlations were run between individual hippocampal system metrics and longitudinal slopes of visual memory change. There was a significant group by time interaction for long-term visual memory, such that middle-age and older adults with ASD declined faster than matched NT adults. There was no group by time interaction for short-term visual memory. Baseline hippocampal free-water was the only hippocampal system metric that correlated with long-term visual memory change in the ASD group. As one of the first longitudinal cognitive and brain aging studies in middle-age and older adults with ASD, our findings suggest vulnerabilities for accelerated long-term visual memory decline, compared to matched NT adults. Further, baseline hippocampal free-water may be a predictor of visual memory change in middle-age and older adults with ASD. These preliminary findings lay the groundwork for future prognostic applications of MRI for cognitive aging in middle-age and older adults with ASD.

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