I am absolutely bubbling with excitement because I’m about to share what I believe to be one of the most foundational aspects of mental health. By the end of this article, you will have a superior and much more nuanced understanding of what makes people different, and why this is essential to understanding mental illness.
Without further adieu: the role of individual differences, and how they contribute to mental health.
PEOPLE ARE DIFFERENT
First and foremost—and this is one of the most important points, although it’s one that we take for granted—there are individual differences between human beings.
When we look at others, we think that fundamentally, they are experiencing the world the same way that we are. But nothing could be further from the truth.
Looking at our genome alone (which is the collection of our genes), we see that tiny variations in our genome lead to ENORMOUS variation in the way we exist in the world. And on top of this variation in biology, we have a lifetime of unique experiences that have shaped who we are.
As a quick comparison, we share roughly 50% of our genome with a banana, 60% with the common housefly, and 98.9% with the common chimp. But we don’t look quite like relatives, and we most certainly don’t send them Christmas cards. And so, all of this to say that these small changes and variations between us are actually very significant in the way they impact us and our mental health.
THE BIOPSYCHOSOCIAL MODEL: MENTAL HEALTH IS A DYNAMIC SYSTEM
Let’s get a little more specific: what causes a person, as unique as they are, to develop a mental illness?
The biopsychosocial model, which I believe is one of the most important frameworks for understanding mental health, states that mental illness is the result of a dynamic interplay between our biology, psychology, and social environment. Mental health, according to this model, does not exist in a vacuum: it is the ultimate output of all of our life “inputs”.
The basic thesis is that you can’t extrapolate mental illness and look at it alone; you have to look at it as being part of a dynamic system. When in balance, this system makes us psychologically healthy. But when the system is out of balance, it can lead to the development of psychopathology.
THE DIATHESIS-STRESS MODEL: WHAT HAPPENS WHEN THE SYSTEM GETS OUT OF BALANCE?
That leads us to the diathesis-stress model of mental illness, which describes what happens when this system gets out of balance.
The diathesis-stress model essentially states that psychological disorders result from an interaction between a preexisting vulnerability and an external stressor. So you encounter a major stress in your life. Will you develop depression? Anxiety? Well it’s not so obvious, It depends, what were you already at risk for?
This, in part, explains why one person may develop anxiety whereas another may develop depression in response to the same stressful event.
So the key idea is we all have particular vulnerabilities, like a chair with one loose leg: only when too much pressure is applied will it give out where it was already liable to fall. And so, this means each of us has a unique tipping point, or psychological thermostat as I call it—a capacity after which point a stress becomes too much.
GENETIC DIATHESES: THE ROLE OF DIFFERENTIAL SUSCEPTIBILITY
Let’s take a specific example of a particular vulnerability, or a wobbly chair leg. Let’s look at genetic vulnerabilities.
When it comes to genetic diatheses underlying mental illness, I like to take the differential susceptibility model as an example. Differential susceptibility essentially means that individuals are affected to different degrees by their environment because of their genes.
A stellar example of this is the contrast between the dandelion and the orchid. The orchid is a beautiful flower, but can only grow when situations are favorable for its development; it’s very sensitive to slight changes in its environment. Whereas the dandelion, you can’t stop these things from growing no matter the circumstance—they grow on the edges of concrete, without any interference or care. Basically, they have minimal needs from their environment in order to grow and are largely unaffected by changes in their environment.
Interestingly, similar differences exist in humans at the genetic level. One such example at the genetic level is the serotonin transporter gene. Serotonin, as you may know, is one of the key neurotransmitters that stabilizes our mood and imbues us with feelings of well-being and happiness. To get serotonin into presynaptic neuron from the synaptic cleft, we have a serotonin transporter gene which controls how quickly serotonin is able to be reused in our cells. Remember: for every gene, we have two alleles which determine what the ultimate expression of the gene will be, and for the serotonin transporter gene, we have the long allele (l) and the short allele (s).
While there are few “genes” for mental illness, research has consistently shown that individuals with two short alleles (ss) are more prone to negative emotionality, depression, anxiety, and neuroticism. Also, individuals with two short alleles tend to show greater amygdala activation and heightened baseline arousal levels. So, in short, similar to the orchid, individuals with the short allele tend to be more sensitive to their environment.
That’s just a brief overview of the genetic contribution to individuality in terms of mental health. And I’ll point out an important caveat: no matter your biology, you can prepare to be well by engaging in health-promoting habits.
What do you think are some important factors that make human beings different in the way they respond to stress? Are you sensitive to your environment? Let us know in the comments below ⤵