When a child is born, family and friends rush to point out the physical traits they’ve acquired from their parents, like nose shape or eye color. As the child grows older, behavioral traits such as frequent mood swings or loud outbursts may get attributed to the parents as well. It’s no coincidence that these behaviors can carry over from parent to child, just as physical traits do — it’s partly genetics.
Through a tremendous amount of study, scientists have discovered clear links between DNA and some mental health characteristics. As this research continues to expand, it raises questions as to why mental health genetic science isn’t as widely known or accepted as physical genetic science. How can specific genetic variants potentially predispose people to certain types of behavior, and how has this science been applied in practice?
The journey to link mental health and DNA might surprise you.
Exploring Mental Health Through Genetics
Every individual has a genetic makeup, called a genotype, that consists of a DNA code inherited from both parents. This genotype influences many biological processes, from cell development to brain function. While many factors, including environment and lifestyle, influence behavioral traits, a person’s genes can influence their predisposition for such traits.
In other words, mental health is partly influenced by DNA. Over the past two decades, scientists have analyzed thousands of genes for links to specific psychological traits and mental health conditions. However, as research on mental health genetic science has moved slowly, advancements in physical health genetic science — such as the heredity of metabolic and cardiovascular conditions — have skyrocketed.
To better understand why psychological studies have been delayed, it’s important to revisit the history of genetic science as it relates to mental health.
When Were Genes First Linked to Psychological Traits?
The history of linking genes and psychological traits is more than 200 years in the making. Initial interest was first generated in the year 1800 with Mendel’s Law of Heredity. Austrian monk Gregor Mendel conducted multiple experiments cross-breeding various sizes and shades of pea plants, becoming the first individual to conceptualize the transfer of visible traits from parent to offspring.
In 1875, Sir Francis Galton began research in twin studies, assessing if those with visibly identical traits could share similar psychological traits as well. By 1903, the term “genetics” was officially coined by Danish pharmacist Wilhelm Johannsen, who proved the constancy of the genome. Once James Watson and Francis Crick described the double helix of DNA in 1953, research into the link between psychological traits and the genome was just a matter of time.
It was then that researchers began to investigate if specific gene variants were responsible for certain psychological traits or related mental health disorders. However, it wasn’t until the Human Genome Project began in 1990 that international scientists were able to band together to investigate the base pairs that comprise human DNA, as well as attempt to identify and map the human genome from a physical and psychological standpoint.
How Does This Progress Compare to That of Physical Health?
Today, genes can help healthcare providers understand a variety of physical conditions — for instance, within 48 hours of a child’s birth, a blood sample can be analyzed for up to 50 diseases, including hypothyroidism, phenylketonuria (PKU), and sickle cell disease.
Yet, this data is not as commonplace for mental health genetic science. When examining exactly why genetics has made relatively more progress in physical health than mental health, the answer may be the multiple non-genetic factors that contribute to mental health and our poor understanding of the physiology of psychiatric conditions. Still, genotyping has made strides over the last decade.
Genotyping is the process of analyzing an individual’s genetic makeup to locate sequence variations that can help link relevant genes to specific traits. Throughout the ‘90s and early 2000s, the price of DNA genotyping was quite high. Without the ability to rapidly sequence entire genomes cheaply, genomic research has been focused on understanding the genetic mechanisms in disease development, prioritizing physical concerns over mental concerns.
When Did Genetic Testing Pivot Towards Mental Health?
The human genome is composed of nearly 3 billion base pairs. When pivoting toward mental health studies, researchers turned to “candidate genes” — genes they believed were related to the studied trait — to identify single-nucleotide polymorphisms (SNPs) that were more or less frequent in some individuals with a psychiatric condition, compared to others.
However, it wasn’t long before scientists realized that mental health traits are linked to hundreds or even thousands of genes, each of which contributes to that trait’s heritability and works in conjunction with an individual’s environment, experiences, and lifestyle.
For instance, a mental health disorder such as schizophrenia is approximately 50 percent heritable, and autism is about 70 percent heritable. However, these conditions are variable, meaning a predisposition alone does not equate to diagnosis. Instead, past traumas, current lifestyle, and an individual’s surrounding environment, combined with their genetics, help shape their mental health.
To expound on the relationship between the human genome and specific psychological conditions, scientists created the field of genomic psychology, and with it, genome-wide association studies.
The Rise of Larger-Scale Studies
The current gold standard for conducting gene-trait or gene-disease associations is the GWAS or Genome Wide Association Study. A GWAS is a research method in which large or entire portions of an individual's genome are evaluated and compared to many other individuals. Using statistical analysis and clinical or behavioral information, researchers can compare two groups of people to identify certain genes that may be more common in one group than the other.
In mental health, a GWAS might compare the genomes of people who have anxiety-like traits (phenotype) to people who don’t have it, and then see if any genes are more frequent in the former group.
The results are typically displayed in what’s called a “Manhattan Plot,” which outlines how many genes are significantly associated with a trait or condition. While there have been several gene variants found to be associated with each mental health condition, this does not necessarily mean they cause the condition. Rather, most mental illnesses are polygenic, meaning they are associated with many gene variants and Manhattan Plots cannot be used diagnostically.
Moreover, due to the associations of trauma and lifestyle with mental health conditions, it’s doubtful that genetics alone can be diagnostic in the field of mental health. Fortunately, the explosion of genetic knowledge combined with the ability to rapidly sequence entire genomes cheaply has led to the performance of thousands of GWAS, which can be used to shed light on an individuals' predispositions to certain feelings and behaviors.
Personalized DNA Testing for Mental Health
The findings of those thousands of GWAS represent the foundation on which the Genomind Mental Health Map™ was built. The DNA-based assessment tool represents an easy-to-use source of genes related to mental wellbeing. The panel of genes analyzed on the test have been associated with distinct behavioral predispositions across 7 Core Genetic Mental Health Capabilities™, including Stress & Anxiety, Mood, Social Behavior, and more. The reports pair understandings of GWAS with your genetic variants to provide an in-depth analysis of your genetic predispositions.
By identifying your genetic predispositions, the Mental Health Map gives you an important foundational understanding for addressing your mental health and wellness concerns. It pairs actionable insights with personalized recommendations to sustain and improve mental wellness. No prescription is required.
What’s Next for Mental Health Genetic Science?
In the future, the hope is that products such as the Genomind Mental Health Map™ will help people save time, frustration, and expense by facilitating more meaningful conversations and offering genetically based insights to support a mental health and wellness plan.