May is Mental Health Awareness Month, so to continue with our trend of investigating the underpinnings of the brain, we are dedicating this month’s series to the origins and treatments of mental illness. Due in part to the innate complexity of the human brain, the roots of mental illness can be extraordinarily complicated to untangle. Many psychologists use what is known as a biopsychosocial approach to understanding mental health. This approach acknowledges that mental illness emerges from an interconnected web of biological, psychological, and social factors. Reducing any mental illness to simply a matter of faulty neurochemistry, a product of childhood trauma, or the result of a dysfunctional thought pattern will always paint an incomplete picture. One set of common mental disorders that routinely gets oversimplified is mood disorders—like depression and bipolar disorder. Roughly one in ten Americans suffer from some form of mood disorder, which can have serious consequences for their personal relationships and overall wellbeing. Mood disorders are strongly rooted in neurochemical imbalances, which can make them seem straightforward to treat and overcome. But the biological perspective is only one, fairly narrow lens with which to understand mood disorders. Understanding, treating, and overcoming mood disorders requires a much more holistic and empathetic approach.
Humans are capable of a vast array of emotional states that can interact and even contradict each other from one moment to the next. Emotions arise in response to the external or internal world in ways that are colored by our experiences and personalities. Emotions are frequently transient, changing in response to new stimuli. Moods, on the other hand, are defined as longer-term dispositions that can arise from emotions but ultimately outlive the original emotional trigger. Moods are typically more broad and nebulous—whole sets of emotions can combine to form either a good or bad mood. A mood disorder is characterized by the ongoing dysregulation of mood that can warp perception and impair day-to-day functioning. People with mood disorders can experience moods that are out of proportion to or completely unprovoked by emotional triggers.
Depression is really a catchall term for a variety of depressed mood disorders. Major depressive disorder is characterized by ongoing depressed mood and loss of interest in day-to-day activities. There are many other symptoms that are associated with major depressive disorder—like dramatic changes in weight, disrupted sleep, fatigue, or difficulty concentrating. Each person’s experience with depression is unique, but psychologists usually look at the sum of symptoms the person is experiencing and the length of time they’ve experienced them in order to confirm a diagnosis of major depressive disorder. Major depressive disorder is an episodic condition, meaning that the symptoms may flare up (sporadically or in response to a stimulus) and then abate after a certain amount of time. But having one episode of major depressive disorder greatly increases your risk of experiencing another episode in the future.
A subset of people experience a less episodic form of depression known as persistent depressive disorder (or dysthymia). This form of depression is characterized by ongoing depressed mood that can last for years. Other types of depression are usually characterized by the different events that can trigger them. Seasonal depression refers to a pattern of depressive mood associated with the darker winter season. Postpartum depression is characterized by a depressed mood and sense of agitation that can plague mothers after giving birth.
Depression involves an episodic or persistent negative mood, but mood dysregulation can also apply to “positive” moods. Another set of mood disorders, known as bipolar disorders, are characterized by cyclic and often erratic swinging into depressive or manic moods. Despite being the other side of depression, mania isn’t really a positive mood. A manic episode is characterized by at least a week of intense, agitated excitement or irritability, which can lead to paranoia, delusions, and risky behavior. In the moment, mania can feel overwhelmingly positive, often involving a pervasive sense of productivity, vigor, and self-confidence. But the high is not sustainable, and people coming out of a manic episode have to grapple with the consequences of their erratic and risky behavior. The different forms of bipolar disorder are primarily described by the types of episodes a person may experience. Bipolar I is characterized primarily by episodes of mania that can be interspersed by depressive episodes or hypomania (mania that lasts for less than a week). Bipolar II is characterized by depressive episodes interspersed by episodes of hypomania. People who experience some ongoing subset of symptoms associated with hypomania and depression, but not enough to be diagnosed as bipolar, are often diagnosed with cyclothymic disorder.
There is strong evidence that biology plays an important role in the development of mood disorders. Genetic studies have demonstrated that you are two to three times more likely to experience major depressive disorder if at least one direct family member has depression. And if that family member is a twin, you have a roughly 50% chance of developing the disorder. Similarly, if your twin has bipolar disorder, you can have up to an 80% risk of developing it. Direct family members of people with bipolar have a 10–20% risk—ten times the general population risk of 1–2%. There have been several studies identifying possible genes contributing to mood disorders, but there is still a lot to learn. Like many heritable psychological phenomena, the genetics of mood disorders is more likely to be the result of many different genes and biological interactions.
Mood disorders are linked with abnormal brain activity in areas of the brain that regulate our emotional response to stimuli (like the amygdala and prefrontal cortex). There is also strong evidence that neurotransmitter imbalances are linked to mood disorders. Too little of the neurotransmitters serotonin or norepinephrine is linked with episodes of depression, which is why one of the most common treatments for depression is a selective serotonin reuptake inhibitor (SSRI). SSRIs work by effectively blocking the reuptake of serotonin in the synapse, allowing it to continue stimulating the neuron. Bipolar disorder is even more complicated because it encompasses both depressive and manic episodes, which can be related to many different neurotransmitter systems. Lithium, a mood stabilizer commonly prescribed for bipolar, interacts with many of these systems to regulate mood.
Another biological element that has been linked to a higher risk of depression is high levels of the stress hormone cortisol. Of course, stress isn’t only biological—it often arises from external situations and our reaction to them. There is a growing amount of evidence that suggests intense psychological stress can trigger changes in the brain, neurochemistry, and hormones that can contribute to a depressive episode. It’s impossible to know if a stressful event will trigger a depressive episode. There are biological factors to consider, but we also each respond to stressful events in different ways that stem from our unique thought patterns and experiences. Some people may be predisposed to focus on the negative aspects of events or associate events with preexisting negative schema. Depression is strongly tied to feelings of hopelessness and powerlessness, and some people are going to be more predisposed to those mindsets than others. The biological, social, and psychological factors involved in depression converge in each patient in profoundly unique ways. As a result, most doctors recommend a combination of medication and cognitive therapy to manage depressive disorders.
Next week, we’ll dive into the science of anxiety and panic disorders. For now, check out last month’s series on the psychology of perception and cognition. Comment on this post or email me at contact@anyonecanscience.com to let me know what you think about this week’s blog post and tell me what sorts of topics you want me to cover in the future. And subscribe below for weekly science posts sent straight to your email!
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- https://suicidepreventionlifeline.org/
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