This new study on older adults with bipolar disorder shows why some people don’t notice their own memory or thinking has slipped, even when people close to them do. Researchers compared how well someone’s brain performs right now on standard tests, and an estimate of how sharp they probably were before their illness took hold (using vocabulary skills, which tend to stay stable over a lifetime even when other mental abilities decline).
The gap between those two numbers turned out to matter. People with a bigger gap (meaning they’d dropped more from their personal baseline) tended to struggle more in daily life, even when their current test scores looked “normal” by population standards.
That last part is the key insight. Standard cognitive tests compare you to everyone else your age. But if you started out exceptionally sharp, you can lose a lot of ground and still land in the average range. To an outside observer, and even to a standard test, you’d look fine. Meanwhile, you might be quietly struggling with work, relationships, or daily tasks because you’re not operating at the level you used to.
The researchers argue this matters most for people who were high achievers (professionally and academically) because their decline is the most likely to be missed. Normal test scores can mask a real, personally significant loss.
To clary, this gap measure was a useful predictor, but not as strong as just measuring current cognitive performance directly. The real value isn’t replacing standard testing, it’s catching the people who’d otherwise slip through the cracks of “you tested normal, so you’re fine.”
It’s a reminder that “normal for your age” and “normal for you” aren’t always the same thing, and the difference can be the whole story.
Link to full article: https://doi.org/10.1016/j.jad.2025.120094