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ABO Blood Types

All humans have a blood type, and there are only 4 possibilities: A, B, AB, or O. There is also a Rhesus Factor, which is shown as either a negative (-) or positive (+) sign after the blood type. (Example: A+, B-, AB+, O-)

I was curious if people with ADHD more commonly had a specific blood type, and if so, what it was. After falling down a Google Rabbit Hole, I found this article for a study conducted in 2009. It states in its abstract that the risk for ADHD increases if alleles A or O are present, and the risk decreases if the B allele is present. In other words, people with A or O alleles are more likely to have ADHD, and people with B alleles are less likely to have ADHD.

Before you scroll down to see the results, I want to make something clear: I did not test the alleles for the respondents; I only recorded their blood type.

The difference between alleles and blood types:

Remember in high school when you learned about Punnett squares? That idea applies here. You have two alleles from each of your parents for your blood type. You can only receive the alleles that they possess. Alleles A and B are both dominant, while the O allele is recessive. You can only have Type O if you received an O allele from both parents.


However, you can still have an O allele if you have type A or type B. Since A and B are both dominant, the presence of O does not affect the blood type of the person. If you have type A, you could have alleles AA or AO. If you have Type B, you could have alleles BB or BO. If you have Type O, you must have OO, which is still possible if your parents are type A or A, but only if they are heterozygous (AO or BO).

What about AB? That's simple: You must receive an A allele from one parent and a B allele from another parent. If you have AB, there's only one possibility for your genotype: AB. (Just like there's only one possibility for O, which is OO.)

Like I said, I did not test the actual genotypes/alleles for respondents. So it's important to remember that these results aren't necessarily telling of anything, because the people with types A and B may very well have an O allele present.

Survey Demographics

Number of participants: 362

Participants with a confirmed ADHD diagnosis: 225

Participants without a diagnosis, but suspect ADHD: 112

Participants that do not have ADHD: 25

ABO Blood Types (1).png

Figure 1: ABO Blood Types. Of the 362 participants, 33.43% reported Type A, 12.98% reported Type B, 5.25% reported 5.25%, and 48.34% reported Type O. Type O was less common in individuals without ADHD at 36%, and Type B was more common in individuals without ADHD (36%).

ABO Blood Types_ Rhesus Factor (+_-).png

Figure 2: Prevalence of Rhesus Factors. Of the 362 participants, 26.8% reported negative blood types and 73.2% reported positive types. Neurotypicals reported more negative blood types than positive; the opposite of the ADHD group and Possibly ADHD group.

ABO Blood Types + Rhesus Factors (+_-).png

Figure 3: Prevalence of complete ABO Blood Types, including Rhesus Factors. Of the 362 participants, O+ was the most common blood type at 32.04%, followed by A+ (26.24%) and O- (16.3%). The least common type among the entire population of respondents was AB- (1.1%).

Like what you see?

I design my surveys from scratch using Google Forms. It takes careful planning to word the questions and response options in a way that's easy to understand, descriptive (but not wordy), and inclusive to all participants. The work doesn't stop there. Once surveys close, responses are exported to spreadsheets, where the data is organized, abbreviated, color-coded, and analyzed to locate significant results. This step alone can take up to 14 hours. Finally, the data is visualized via simple-yet-informative charts and shared on social media and our website. This requires an additional 3-6 hours of formatting, coding, and drafting figure legends. From start to finish, the surveys and respective data take a minimum of 20 hours to complete.

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