Why IQs are falling — and what to do about it

For most of the 20th century, average IQ scores in industrialized countries went up — about 3 points per decade. Then, around the mid-1990s, they started going down. Younger generations are now scoring lower than their parents did at the same age.

This is not a small effect, and it is not a one-country anomaly. The reversal has been documented in Norway, Denmark, France, the UK, Finland, Estonia, Australia, and the Netherlands. It has a name: the negative Flynn effect.

James Flynn was a political scientist who, in the 1980s, noticed something strange: every time IQ tests got renormalized to a new generation, the previous generation's scores looked higher than the test designers had assumed. Children of the 1980s scored, on average, 30 IQ points above children of the 1900s — using the *same* test.

For decades, this rise (about 3 points per decade) was the dominant pattern. Causes proposed: better nutrition, smaller families, more schooling, more abstract reasoning embedded in modern life, the disappearance of lead from gasoline. The exact mix is still debated. The upward trend is not.

Bratsberg and Rogeberg (PNAS, 2018) had a clean dataset: every Norwegian male takes an IQ test at military conscription, going back decades. They tracked the scores of brothers born years apart in the same family — controlling for genetics and home environment as tightly as you can in a real population.

The finding: the rise stopped around 1975 and reversed around 1995. Each cohort since has scored slightly lower than the one before. The effect is *within families* — same parents, same household, lower scores in the younger sibling. This rules out many demographic explanations.

Dutton, van der Linden and Lynn (2016) ran a meta-analysis across 14 nations and reached the same conclusion. The OECD's PISA program — which tests 15-year-olds in math, reading and science across 70+ countries — has reported declining math scores for over a decade, including the steep drop measured in 2022.

Honest answer: nobody knows for sure. The plausible mechanisms cluster around two themes.

Reduced effortful reading. Long-form reading — the kind that builds the working memory and abstract-vocabulary muscles IQ tests measure — has collapsed in the smartphone era. You don't need a study to feel this. Most adults under 40 have not finished a book they started in the last six months. (You can check: when did you last?)

Attention fragmentation. Continuous notifications, infinite scroll, and short-form video have replaced sustained focus with rapid task-switching. The cognitive cost of switching is well-documented. The cumulative effect on developmental trajectories is not — but the direction is consistent with what we see.

Secondary candidates: declining school standards, rising screen time in early childhood, micronutrient changes in modern diets. Not zero contribution, but probably smaller.

The mechanism that's most clearly within your control is deliberate effortful thinking. Not 'staying mentally active' in the vague sense — actually doing something cognitively hard, daily, for a sustained stretch. Reading a difficult book. Working through a math problem instead of looking up the answer. Writing something coherent rather than dictating fragments to a chatbot.

This is not a medical claim. Solving math problems will not raise your IQ score by 10 points. But there is good evidence that sustained effortful cognition is associated with maintained cognitive performance over time — and that the modal adult, in 2026, is not getting much of it.

So: start small. The minimum viable habit is the one you'll actually keep. Read 10 pages. Solve three problems. Write 200 words. Pick one. Do it daily. The compounding is the point.