OSLO — A large-scale Norwegian study has documented a decline in IQ scores among men, a trend that began in the 1970s and has puzzled researchers, with no single cause identified. The 2024 study, which examined data from 579,379 men, did not pinpoint one definitive reason for the drop. Instead, researchers have proposed several hypotheses, and the findings point to a complex web of environmental and social changes affecting cognitive development across generations.
The study found that the steepest decline occurred among the sons of high-income fathers, a result that may point to factors more prevalent in wealthier households.
Possible factors under scrutiny
Researchers have put forward several potential explanations. Changes in family structure — including smaller family sizes and an increase in single-parent households — may reduce the level of cognitive stimulation children receive at home. Increased screen time and reduced reading have been linked to lower cognitive performance in some studies.
Nutritional changes have also been suggested, specifically a reduced consumption of omega-3 fatty acids. The study’s authors are calling for further investigation into these environmental and social changes.
They stress that isolating specific causes will require more research, as the decline appears to be driven by multiple, interacting factors rather than a single cause.
A generational shift
The fact that the decline began in the 1970s means it has been unfolding for over five decades. This is not a sudden drop, but a gradual trend that has been shaping the cognitive abilities of successive generations of young men. The researchers emphasise that further work is needed to understand the full picture.
The study opens the door to more detailed investigations into how modern life — from diet to digital habits to family dynamics — is influencing the developing brain.
Sources
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