This mental strain could be costing poor people up to 13 IQ (intelligence quotient) points, researchers said.
As a result, people of limited means are more likely to make mistakes and bad decisions that may be amplified by - and perpetuate - their financial woes, according to an International team of researchers.
The researchers suggest that being poor may keep a person from concentrating on the very avenues that would lead them out of poverty.
A person is left with fewer "mental resources" to focus on complicated, indirectly related matters such as education, job training and even managing their time, they said.
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Researchers found that pressing financial concerns had an immediate impact on the ability of low-income individuals to perform on common cognitive and logic tests.
On average, a person pre-occupied with money problems exhibited a drop in cognitive function similar to a 13-point dip in IQ, or the loss of an entire night's sleep.
"These pressures create a salient concern in the mind and draw mental resources to the problem itself. That means we are unable to focus on other things in life that need our attention," said Zhao, a University of British Columbia professor.
"We're arguing that the lack of financial resources itself can lead to impaired cognitive function. The very condition of not having enough can actually be a cause of poverty," said Zhao in the study published in journal Science.
The first set of experiments took place in a New Jersey mall between 2010 and 2011 with roughly 400 subjects chosen at random.
To better gauge the influence of poverty in natural contexts, between 2010 and 2011 the researchers also tested 464 sugarcane farmers in India who rely on the annual harvest for at least 60 per cent of their income.
Because sugarcane harvests occur once a year, these are farmers who find themselves rich after harvest and poor before it. Each farmer was given the same tests before and after the harvest, and performed better on both tests post-harvest compared to pre-harvest, researchers said.