Age and cognitive skills: Use it or lose it
# | #aging, #science, #biology
Cross-sectional age-skill profiles suggest that cognitive skills start declining by age 30 if not earlier. If accurate, such age-driven skill losses pose a major threat to the human capital of societies with rapidly aging populations. We estimate actual age-skill profiles from individual changes in literacy and numeracy skills at different ages. We use the unique German longitudinal component of the Programme of the International Assessment of Adult Competencies (PIAAC-L) that retested a large representative sample of adults after 3.5 years. Our empirical approach separates age from cohort effects and corrects for measurement error from reversion to the mean. Two main results emerge. First, average skills increase strongly into the forties before decreasing slightly in literacy and more strongly in numeracy. Second, skills decline at older ages only for those with below-average skill usage. White-collar and higher-educated workers with above-average usage show increasing skills even beyond their forties. Women have larger skill losses at older age, particularly in numeracy.
A first of its kind study to measure cognitive skills over age using panel data. The data is from Germany. Measurements are on literacy and numeracy. For a sample of the questions see literacy and numeracy.
It is not clear if it's surprising that people who work with numbers get better with it until say age 60 (look at the questions - but could be hindsight bias). When people discuss cognitive decline, I don't think they are talking about ability to analyse small amounts of data and multiply and add. Memory, attention, processing speed, learning abilities measured would be interesting. Another sticky problem is correlation vs causation. In this particular metric I feel fairly confident that it's causation to a good extent (numbers do, numbers good), but if the metrics were more interesting the question of living conditions, nutrition, physical excercise, sleep would also have to be controlled for. I have read very little of this literature. As an outsider, my belief is that physical activity greatly helps to offset cognitive decline controlling for other factors.
The differnce by gender is peculiar. It's surprising, or not, depending on the control for other factors like white-collar and blue-collar.