Cognitive Testing

Testing your own cognition is the only way to know whether a supplement or a habit change did anything for you, but repeated testing has a built-in trap: you get better at the test itself. When 36 healthy adults were tested seven times over a year, most tests showed clinically relevant practice effects during the frequent sessions up to month three - effect sizes of 0.36 to 1.19, largest early on - before performance levelled off (Bartels et al., 2010, BMC Neuroscience).

So run several practice sessions before you start counting a baseline, test at the same time of day under the same conditions, and judge any change against the spread of your own baseline rather than against your first score. Blood-panel services such as those reviewed here measure biomarkers, not cognition; they answer a different question, and a result outside a reference range is a reason to repeat the test or see a clinician, not to add a supplement.