"The study used powerful statistical tools to test five hypotheses about the link between mental illness and poverty, including the ''downward drift" idea. The theory that stressful economic conditions bring on mental illness was the only one that really fit the data"
"we experimentally induced thoughts about finances and found that this reduces cognitive performance among poor but not in well-off participants. Second, we examined the cognitive function of farmers over the planting cycle. We found that the same farmer shows diminished cognitive performance before harvest, when poor, as compared with after harvest, when rich. This cannot be explained by differences in time available, nutrition, or work effort. Nor can it be explained with stress"