Different forms of intelligence show unique genetic links to psychiatric conditions

Key Points:

• A large genetic study published in Nature Communications reveals that different types of intelligence—reaction time, fluid reasoning, and crystallized knowledge—have distinct genetic links with various psychiatric conditions such as schizophrenia, bipolar disorder, ADHD, autism, and Alzheimer’s disease.
• The genetic risk for schizophrenia and bipolar disorder is associated with lower processing speed and fluid reasoning but higher crystallized knowledge and noncognitive educational skills, suggesting complex cognitive trade-offs linked to these conditions.
• ADHD genetic risk correlates with faster reaction time but lower fluid reasoning, crystallized knowledge, and noncognitive skills, while autism risk is linked to higher crystallized knowledge, and Alzheimer’s risk is tied solely to lower fluid reasoning capacity.
• The study identifies 78 genetic loci related to crystallized knowledge, including five previously unknown, and maps their activity across brain regions and developmental stages, highlighting how different cognitive abilities emerge at distinct life phases.
• Researchers propose that some genetic variants increasing psychiatric risk may persist due to antagonistic pleiotropy, where the same genes confer cognitive or motivational advantages that enhance reproductive or social success, but findings are limited by the primarily European ancestry of the genetic data and methodological constraints.