The graph of doom: the downward slope of cognition with ageing

Back in my early 20s, I confidently studied neuropsychology, learning that ‘fluid’ skills like processing speed peak in our early 20s, while ‘crystallized’ knowledge such as vocabulary improves into our 60s. At the time, this trajectory seemed logical—and not particularly daunting. As neuropsychologists, we were trained to compare adults to their age-matched norms when assessing the impact of brain injuries or diseases.

Now, as I prepare for a seminar on this topic for junior psychologists, I find myself reflecting on my own experience. At nearly 50, while managing multiple roles—including different jobs, a business, teenage kids, and maintaining a strong partnership with my husband—I’m beginning to question the ‘truth’ of this cognitive decline graph. While my processing speed may have slowed slightly, my ability to juggle complex relationships and the cognitive demands of my work has only increased.

So, what does current research say about aging and cognition? Advances in research methods, including large-scale web-based testing, now suggest that reality is more nuanced, with different tasks peaking at different ages. While some aspects of cognitive function do peak in the early 20s (e.g., processing speed and working memory), others peak in the late 20s and 30s (e.g., attention and short-term memory), and still others in the 30s to 50s (e.g., long-term memory and general knowledge). There is also research suggesting that emotional regulation, wisdom, and social cognition continue to develop into the 60s and beyond.

The evolving understanding of cognitive ageing shows that while some abilities may decline, others continue to grow and adapt, highlighting the complexity and resilience of the human mind. This might explain why, at 50, I feel as if I’m handling more than I ever did at 20!

For those interested in the topic, here’s a recent article from Scientific American: Many Older People Maintain and Even Gain Cognitive Skills.

As research continues to evolve, so too does our understanding of the aging brain, reminding us that aging is as much about growth as it is about change.