Comment by ja3k

The article acknowledges that the study does not show causation and it seems a little strange to think a causal arrow in this direction is more plausible than the other direction. It seems like people who do better at thinking and memory tasks should also do better at their jobs and interviews and therefore be less likely to experience an income drop. To speculate on income drop's effect on mental acumen one would want to measure intelligence at the beginning of a career and in middle age and then correlate the delta to number and size of income drops.