In 2009, the famous biologist ROBERT SAPOLSKY gave a class on depression at Stanford, which is still considered to be one of the most clear and vivid lectures on depression. Combined with his thirty years of research on stress stress response, it is organized as follows.
In terms of human illness, there are few illnesses as bad as depression. It is diffuse, paralyzing, and obliterates all capacity for joy, hope, and pleasure. Cancer patients are sometimes grateful for their illness because it wakes them up, gives them a new perspective on life, and helps them rebuild the relationships that are important in their lives. But this is not the case with depression. The most fundamental characteristic of depression is that it takes away a person’s ability to be pleasant.
The ability to derive joy, hope, and meaning even in the most difficult situations is one of the most surprising human abilities, and in that sense, what could be more frightening than depression?
Professor Sapolsky comes up with an unusual perspective – depression is not a mere psychological illness, but a real disease with deep biological roots, just like diabetes – hormonal and chemical reactions out of control are the common features of both disorders. So, to understand depression, one must look at both the physical and psychological perspectives.
First, let’s look at the basic symptoms of depression.
1. Pleasure deficit disorder: the inability of anything to bring pleasure or joy, whether it is wealth, promotion, or achievement. Grief: sadness, loss, hopelessness, obsessions, delusions, guilt: self-blame for all real or imaginary failures, self-blame for self-blame, self-blame for self-pity Self-harm: hurting oneself, cutting, suicide, and other forms of pain inflicted on oneself, suicide is one of the leading causes of death among young people.
2, psychomotor block: thinking, walking, and doing anything feel exhausted. It is extremely difficult to take any step forward. On a chemical level, this may be related to a dopamine deficiency. Rather than being a hormone in charge of incentives, dopamine is a drive mechanism that drives a certain behavior in order to obtain a reward. Once the possibility of obtaining a reward is suspected, this hormone is also not available. Once the psychomotor block phenomenon slows down, the likelihood of suicide goes up because you have enough drive.
3, vegetative symptoms: Some people accuse depressed people of being self-inflicted abuse, weak, selfish and irresponsible, when in fact, physiological data show that they have a huge stress response, even in the sleep state.
4. Sleep changes: frequent early awakenings. Disturbed sleep cycles.
5, appetite: ordinary people rely on eating to get rid of depression, but depressed people have no appetite for eating at all stress stress stress response: sympathetic nervous system is activated (adrenaline), glucocorticoids gush out. While on the outside they appear to be lazy and tired, as if nothing is happening, inside the body is experiencing a huge stress response, no less than being chased.
Biological perspective:The chemical reactions behind the symptoms of depression
1. Neurotransmitters
Nerve cells communicate with each other through chemical messengers, i.e. neurotransmitters. There are about 100 kinds of neurotransmitters known, but only a few of them are related to depression.
(1) norepinephrine orthoepinephrine.
norepinephrine is basically a stimulant (so it raises blood pressure) and a lack of this neurotransmitter means a lack of stimulants and thus not enough motivation and energy to direct action. It is directly related to the “psychomotor block” of depression symptoms.
When neurotransmitters enter the receptor cells, they usually undergo a metabolic process, and the earliest antidepressants (early 1950s) were based on the principle of inhibiting this metabolic process and increasing the concentration of Norepinephrine.
(2) Dopamine.
Dopamine is the brain’s “reward center”, this transmitter is mainly responsible for the brain’s lust, sensation, transmission of excitement and happy information, but also associated with addiction. Cocaine acts on the dopamine system, and the intensity of dopamine secretion in the brain during love can compete with the pleasure of smoking cocaine.
Dopamine deficiency directly contributes to the “pleasure deficit disorder” of depression.
(3) Serotonin serotonin.
Serotonin is a calming neuroregulator that is produced when people are in a happy mood and affects appetite, mood, and comprehension of the environment. Serotonin deficiency is associated with grief and guilt in depression, and serotonin can also improve obsessive-compulsive disorder, cleanliness, etc. Fluoxetine, the main ingredient of Prozac, was developed in the 1980s to improve psychological conditions by inhibiting the metabolism of serotonin.
Most of the remaining symptoms of depression are related to a combination of these three key neurotransmitter deficiencies.
(4) Substancep Substancep
Substance p is released when the body experiences pain (whether acute or chronic). drugs that inhibit substance p can also alleviate depression, showing that the body uses real pain channels to experience psychological pain.
2, brain structure – the trinity structure of the brain
Neurologist Paul. MacLean proposed a hypothesis that envisages not one but three brains in the human cranial cavity. These three brains as the product of different stages of human evolution, in order of appearance, overlaid on top of the existing brain layers, as archaeological sites, Paul called it the “trinity of the human brain” structure.
The reptilian brain: controls the muscles, balance and automatic functions of the body, such as breathing and heartbeat; the limbic system (paleomammalian brain): is closely related to emotion, intuition, feeding, fighting, escape, and sexuality; and the neocortex (neomammalian brain): is the higher brain or rational brain, responsible for reason and thinking.
In the face of stress, the neocortex, by thinking abstract thoughts, such as the poor children in the slums, can trigger a full stress response in the rest of the brain as well as the body, which is as intense as walking down the road and suddenly encountering a tiger, or a frontal attack by a masked person. Moreover, the more you think about it, the more the negative information channels solidify. From this perspective, what is called depression is a constant whispering of sad thoughts from the neocortex to the rest of the brain.
There is an area in the brain stem part of the brain called the reticular stimulation system, which functions to increase one’s alertness and arousal. For example, when you look for something brown in a room, you will see far more brown than green. When you ask the brain to recall five good things it did today, it will do so; or if you ask it to recall five bad things it did today, it will also do so. So, once the compulsive way of thinking is turned in the wrong direction, a vicious circle will be formed. This could explain why women are more likely to suffer from depression than men, because women are more likely to dwell on negative emotions and thoughts.
3.Hormones
(1) Thyroid hormones
Thyroid hormones, responsible for metabolism, body temperature and energy levels, have a profound effect on growth and development. Inadequate thyroid hormone production can lead to many problems, including depression. Twenty percent of depression is actually undiagnosed degeneration of thyroid function.
(2) Estrogen.
Compared to men, women are at twice the risk of depression, especially around childbirth and during menopause, a time when levels of various hormones fluctuate particularly, and changes in the ratio of progesterone to estrogen in particular are an important cause of depression.
(3) Glucocorticoids.
Glucocorticoids are a stress hormone. When a person feels stressed, a small circuit in the hypothalamus area of the brain releases this hormone, placing the body in a state of heightened alertness. The higher the concentration of glucocorticoids, the greater the danger and stress. Therefore, if you are facing a huge stressor on the one hand, on the other hand, you are still thinking about the matter over and over again in your head, you are likely to end up in the abyss of uncontrollable depression.
(4) Psychological perspective.
Freud made a very important contribution to the study of depression. His research began with the question: Most people who experience something bad will grieve for a while and then get better, but a small percentage of people develop depression, why? In his classic book, Grief and Depression, he analyzed the similarities and differences between the two.
First, both involve the loss of a beloved object (in Freudian terminology, object usually refers to a person, but can also be a goal or ideal). In Freud’s formula, every love relationship necessarily involves conflicting and complex emotions, which means “love-hate”.
In the case of “grief”, you can deal with this complex emotion in a healthy state of mind, focusing on both “love” and “loss”, and recovering from the experience of grief. In the case of “depression”, you dwell on the most negative element of this conflict – the irreconcilable conflict between intense love and hate. According to Freud, depression is an internal conflict generated by contradiction, an aggressionturned inward.
You are faced with a double loss – the loss of a loved one and the loss of the opportunity to resolve this conflict with him or her. You are constantly obsessing over what you did or did not do in the first place. Along with the grief of loss comes a strong sense of guilt – if you really have such a love-hate relationship with the person you lost, the loss itself is more or less a relief, but then you have to harbor guilt for your relief.
Thus, the various symptoms of depression, lack of pleasure, motor nerve block, elevated stress hormone levels, and even suicidal tendencies can all be explained. This kind of great mental attrition caused by inner emotional conflicts.
The connection between physiological and psychological perspectives: the psychological mechanism of “stress” Like most of Freud’s theories, his theories on depression are insightful, but appeal to intuition rather than rigorous scientific verification. The connection between Freud’s theories of love and loss and modern psychological science and biology lies in “stress” itself.
Stress and its psychological mechanisms have been at the forefront of Robert Sapolsky’s 30-year research career, which began more than 30 years ago when he studied baboons in Africa, where he found a hierarchy of animals, with the senior baboons having it all and the junior baboons being miserable, underfed, unappreciated by their mothers and often beaten.
Professor Sapolsky examined the baboons’ stress hormone levels while they slept and found a strong correlation between stress hormone levels and their health status. The lower the baboons, the more stressed they were, and the more likely they were to suffer from high blood pressure and stomach ulcers. To make matters worse, these baboons also like to torment each other – they spend three hours a day feeding themselves and then spend the remaining nine hours stabbing others in the back. So their survival stress is not primarily from lions, or foraging for food, but from chronic social and psychological pressure. This makes them a perfect model for studying human stress.
The human stress response to all stressors is the same, whether the stress is physical or psychological. Although the intensity and duration vary, the internal biochemical response is the same: when a person feels stress, a small circuit in the subthalamic (hypothalamus) region of the brain releases stress hormones that place the body in a state of heightened alertness. This stress response mobilizes life’s potential in a short period of time; your breathing speeds up, your heart rate increases, your blood pressure rises, and glucose levels in the blood spike to provide energy for your muscles. The body also temporarily shuts down all insignificant functions, such as libido, digestion and immune response.
From an evolutionary point of view, this stress mechanism is a means of self-protection for living organisms. Animals have a stress response when they are running for their lives, or when they are chasing prey. But once the crisis is over, the stress response automatically shuts down, so zebras never get stomach ulcers. If the stress response is turned on but not turned off, as it is in the case of the bottom baboons, the constant fear of not being pleased by the female or being bullied by the senior baboons at any time can turn into chronic stress.
Prolonged high levels of hormones deplete the immune system and bone marrow, damage muscle and connective tissue, abnormal insulin metabolism, fluid retention in the interstitial spaces, increased vulnerability to limb damage, and a tendency toward emotional depression.
Robert Sapolsky’s research has found that stress does not directly trigger any single disease, but almost every physical and mental disorder you can imagine is associated with chronic stress, from the common flu, to arthritis, to depression, to diabetes, to heart disease, to Alzheimer’s, to cancer, and more. It increases susceptibility to these diseases by harming the immune system’s ability to fight infection and repair the body. You’ll be more susceptible to viruses, your wounds will have a harder time healing, and you’ll age more easily ……
Of all the stresses, the most dangerous is the feeling of powerlessness – you have no sense of control over an event, no idea how bad the situation will be, how long the pain will last, and no outlet for frustration. Animal experiments have found that when rats experience sustained uncontrollable stress, the amygdala (responsible for perceiving danger and stress responses) area of the brain increases dramatically at the cost of a dramatic shrinkage of the hippocampal gyrus (responsible for memory and learning).
In cognitive psychology, depression is defined as “learned helplessness”. This explains why people who experience the death of a parent before the age of 10 are at a much higher risk of depression, because the age of 10 is an important stage in learning about cause and effect, and you learn in the most frightening way that there are things in the world over which you have no control, and that you are “helpless”.
Depression is a genetic disorder, meaning that it runs in families: if one of the twins is depressed, there is a 50 percent chance that the other will also be depressed. A few years ago, scientists also discovered the SERT gene associated with depression – a gene responsible for regulating the movement of serotonin, which in turn is closely linked to mood.
The SERT gene has two forms, “long” and “short”, and everyone carries any combination of the two SERT genes, those with the “long-long” combination seem less likely to be controlled by Those with the “long-long” combination seem to be less likely to be controlled by low mood, while those with the “short-short” or “short-long” combination are more likely to suffer from depression. Scientists have also found that environmental stimuli, i.e., stressors, are more important than genes in depression – a person with the short SERT gene is more likely to suffer from depression if his or her environment is stressful; however, if his or her environment is healthy, he or she will usually achieve great things.
Finally, Professor Robert Sapolsky re-emphasized that depression is never a momentary lapse in mood or self-loathing, but has deep physiological and biological roots, and is as real as diabetes.