How to Improve Your Memory & Cognitive Function at Any Age | Dr. Alan Castel

What It Covers

UCLA psychology professor Dr. Alan Castel joins Andrew Huberman to examine how human memory forms, declines, and can be preserved across the lifespan. They cover errorful learning, retrieval practice, metacognition, balance training, physical exercise and hippocampal volume, superager traits, and how beliefs about aging directly influence cognitive outcomes at any age.

Key Questions Answered

• •Errorful Retrieval Practice: Attempting to recall information before reviewing it — even when the attempt fails — produces stronger memory encoding than passive re-reading. Drawing the Apple logo from memory without looking, struggling with details, then checking the answer creates deeper learning than repeated exposure alone. This "desirable difficulty" principle applies to any subject: force retrieval first, then correct, rather than reviewing material repeatedly without testing yourself.
• •Hippocampal Volume and Walking: The hippocampus, the brain region central to declarative memory, shrinks roughly 1–2% per year after midlife. A randomized study found that adults assigned to walk 40 minutes three to four times per week for one year increased hippocampal volume by 1%, while a stretching control group showed continued decline. The mechanism likely involves increased cerebral oxygenation and downstream improvements in sleep quality, both of which support memory consolidation.
• •Balance as a Cognitive Indicator: One in four adults over 65 experiences a fall, which triggers inactivity, accelerates hippocampal shrinkage, and compounds memory decline. A simple diagnostic: stand on one leg for 10 seconds with eyes open, then closed. Balance is highly trainable within one to two months through yoga, tai chi, or single-leg standing. Most people overestimate their balance because they have not yet fallen, making this an underutilized early intervention target.
• •Subjective Age Predicts Longevity: After age 40, most people report feeling approximately 20% younger than their biological age. Research shows this subjective age is a stronger predictor of lifespan than chronological age. Holding a younger self-perception correlates with better health behaviors and outcomes. Conversely, being told one's biological age by a physician can activate age-based stereotypes that negatively shape behavior, suggesting mindset about aging functions as a measurable health variable.
• •Memory Contamination in Eyewitness Identification: Once a witness identifies a face in a lineup, that identified face begins replacing the actual memory of the perpetrator during subsequent recall. The Ronald Cotton case illustrates this: a highly motivated witness with extended exposure to her attacker made a cross-race misidentification, and repeated retrieval of the lineup photo overwrote her original memory. Confidence level at identification does not reliably predict accuracy, a principle with direct implications for legal proceedings.
• •Selective Attention Drives Encoding: Familiarity with an object does not produce accurate memory of its features. Most people cannot correctly draw the Apple logo despite thousands of exposures because passive viewing bypasses effortful encoding. Memory formation requires deliberate selection — consciously deciding a moment or detail is worth retaining. Research on photo-taking shows the act of deciding to photograph an event can itself improve memory for that event, even before the shutter fires.
• •Aging Beliefs Alter Cognitive Trajectory: Holding negative stereotypes about cognitive aging accelerates measurable decline, while a positive aging mindset correlates with preserved function. Older adults demonstrated greater psychological resilience than younger adults during COVID-19 isolation, drawing on prior experience with adversity. Superagers — adults in their 80s and 90s whose memory rivals people decades younger — commonly share traits of social connection, physical activity built into daily routine, curiosity, and a sustained sense of purpose rather than explicit longevity-focused protocols.