Schizophrenia and height are both associated with, among other things, hormonal imbalance, brain size, socioeconomic status, infections and nutrition. Neuroscientist Cato Romero therefore investigated which biological processes schizophrenia and height have in common, to see whether this overlap can provide more information about how schizophrenia develops. The study was published in Biological Psychiatry.
Romero and his colleagues used data from large datasets of hundreds of thousands of participants to compare the genetic variation associated with schizophrenia with the genetic variation associated with height. By analyzing DNA variation, they identified genetic markers that relate to both.
Thyroid hormones and immune response
The researchers discovered 142 genes that were linked to both schizophrenia and height. The shared genes showed high expression in the pituitary gland, a small organ that secretes several essential hormones. Within the pituitary, one type of cell, the thyrotrope, stood out in the findings: thyrotropes produce thyroid-stimulating hormone, which regulates the level of thyroid hormones in the body.
In addition, many of the shared genes are involved in the immune response. A large number of genes are active in white blood cells, which help the body fight infection. A link between increased inflammation and schizophrenia has previously been found. It is possible be that the body spends more energy on recovering from infections and therefore less on growth.
Diversity in genetic studies
A caveat to the study is that the evidence for these findings was less robust in datasets from non-European people. This is partly due to the fact that non-European datasets are currently still significantly smaller. According to Romero, there is therefore a need to increase diversity in genetic studies.
For now, this new knowledge about shared genetic mechanisms inspires further research into the exact relation between schizophrenia on the one hand and immune responses and thyroid hormone on the other.