Just a few I found:
The study found that the blood group (AB) received the highest average in the Intelligence Quotient (IQ) test which is also the highest in the GPA. And that the blood type (B) was the lowest in the GPA and in test results.
This study aimed to know the relation between the four blood groups (A, B, AB, O) and intelligence for
universities’ students who reached (194420) students and it was tested on (364) students intentionally
distributed to four equal groups; (91) for each group according to their blood group of six Jordanian
Universities, which are:
Jerash University, University of Jordan, Yarmouk University, Philadelphia University, Irbid National
University, and Al-Balqa’ Applied University.
The study found that the blood group (AB) received the highest average in the Intelligence Quotient
(IQ) test which is also the highest in the GPA. And that the blood type (B) was the lowest in the GPA and
in test results. The researcher recommended to expand the circle of the research to include all
Jordanian universities , other universities and schools in a longer periods of time
Blood type may affect brain function as we age, according to a new large, long-term study. People with the rare AB blood type, present in less than 10 percent of the population, have a higher than usual risk of cognitive problems as they age.
People with O blood type may be more likely to have depression and intense anxiety; children may be at a greater risk of attention-deficit disorder.
People with A blood type may be more prone to obsessive-compulsive disorder; children may be at a greater risk of attention-deficit disorder.
Children with B blood type may have a lower risk of attention-deficit disorder.
https://www.scientificamerican.com/article/blood-type-matters-for-brain-health/