Different cognitive skills have distinct genetic links to psychiatric disorders
A massive genome-wide analysis finds that intelligence is not a single trait: reaction time, fluid reasoning, and crystallized knowledge each have distinct genetic links to psychiatric conditions, with schizophrenia and bipolar disorder tied to slower processing and lower fluid reasoning but higher crystallized knowledge and noncognitive educational skills; ADHD shows faster reaction time but lower fluid/crystallized/noncognitive skills; autism links to higher crystallized knowledge; Alzheimer's risk is linked to lower fluid reasoning. The study identifies 78 loci for crystallized knowledge, maps gene activity across development, notes overlaps with personality traits, and discusses possible evolutionary trade-offs, while highlighting limitations due to data mainly from individuals of European ancestry and urging researchers to treat cognitive domains as separate traits rather than a single score.