Is there evidence that blood types and personality traits are connected?

One of the studies already added was from Harvard:

1964 Harvard Study Indicates Boys With Blood Type A More “Tender-Minded”

It isn’t surprising, that their study was added considering the source. It also isn’t surprising, that they have not continued with studies one would expect showing indications, be it to prove or dismiss.

Some of the newer studies include:

Psychiatric disorders and blood type AB

The results of this study support the hypothesis of an association between psychiatric disorders and ABO blood groups. The probability is that psychiatric disorders will occur almost three times more frequently in carriers of AB group compared to other ABO blood groups in the Croatian population.

And then there is this:

Blood type A and OCD

The relation of ABO blood types to obsessional personality traits, as measured by the Leyton Obsessional Inventory (LOI), was studied in a sample of 600 normal individuals. High scorers of the LOI trait portion demonstrated a significantly lower incidence of phenotype O and a significantly higher incidence of phenotypes AB, A and B, taken together, compared to those of a general population sample and the entire study group. Findings of the present study, in conjunction with previous findings concerning a lower incidence of phenotype O and a higher incidence of phenotype A in obsessive compulsive patients, could be interpreted as indicating that phenotype O may be associated with personality traits hindering the development of obsessive-compulsive symptomatology.

More supports this:

Obsessive-compulsive neurosis, anancastic symptomatology and ABO blood types.

Determinations of ABO blood types was carried out in 38 patients with obsessive-compulsive neurosis, 48 schizophrenics with anancastic symptomatology, 31 depressives with anancastic symptomatology, 260 schizophrenics free of anancastic symptomatology and 65 depressives free of anancastic symptomatology. Results were compared with a representative sample of the general population. The findings of the present study provide evidence of an association between obsessive-compulsive neurosis and phenotype A, whilst a similar association between ABO blood types and anancastic symptomatology occurring in the course of psychotic disorders was not found. The significance of these findings is discussed with regard to current diagnostic and aetiological issues in obsessive-compulsive neurosis.

In blood type O, depression and related conditions repeatedly show study after study:

BLOOD TYPES IN RELATION TO DEPRESSIONS AND SCHIZOPHRENIA: A PRELIMINARY REPORT.

The distribution of the ABO, A(1), D, E, C, and Kell blood types in relation to selected psychiatric diagnoses was studied in over 700 consecutive admissions to a provincial mental hospital. Predicted relationships based upon recent work in other laboratories were supported by consistent trends approaching statistical significance. In addition, blood group O was found to be significantly associated with involutional melancholia.

Our own study discussed some differences based on the rh factor:

Worse Health Status and Higher Incidence of Health Disorders in Rhesus Negative Subjects

The RhD negative subjects expressed many indices of a worse health status. Men, women or both sexes reported more frequent allergic, digestive, heart, hematological, immunity, mental health and neurological problems. They also reported the usage of more drugs prescribed by doctors per day, attended more specialized doctors, namely, dermatologists, gynecologists, internal medicine doctors, neurologists, and psychiatrists (men) in the past two years, a higher frequency of headaches and being tired more often than RhD positive subjects. Incidence of various diseases and disorders also differed between RhD negative and RhD positive subjects, mostly being higher in the former.

Please understand, that this post is only the beginning of what will become a larger list of studies related. Feel free to bring to our attention what we haven’t listed yet. Subscribe to this blog to get alerted of future developments.

Our ongoing focus will be rh negative people and blood.