depression

Depression is a typical condition of depressive disorder, characterized by low mood, decreased interest, pessimism, slow thinking, lack of initiative, self blame, poor diet and sleep, worry about various illnesses, feeling discomfort in multiple parts of the body, and in severe cases, suicidal thoughts and behavior. It is the disease with the highest suicide rate in psychiatry. The etiology and pathogenesis of depression are not yet clear, and may involve various factors such as physiology, psychology, and society. The incidence rate of depression is very high. According to WHO (2012), there are more than 350 million depression patients worldwide, so it is called the cold in psychiatry. Depression has become the second most significant disease worldwide that imposes a serious burden on humanity.

Clinical classification

1. Endogenous depression

Endogenous depression is characterized by the “five signs” of laziness, lethargy, restlessness, worry, and anxiety (relative or absolute deficiency of brain biogenic amines).

2. Reactive depression

Reactive depression refers to depression caused by various mental stimuli and setbacks. In daily life, people with poor psychological resilience, such as sudden natural and man-made disasters, heartbreak, marital changes, serious illnesses, career setbacks, etc., are prone to developing reactive depression.

3. Hidden depression

The symptoms of low mood and depression are not obvious, often manifested as various physical discomfort symptoms, such as palpitations, chest tightness, discomfort in the upper and middle abdomen, shortness of breath, sweating, weight loss, insomnia, etc.

4. Depression characterized by learning difficulties

This type of depression can lead to learning difficulties, decreased attention, decreased memory, overall or sudden decline in grades, aversion to learning, fear of learning, truancy or refusal to learn in students.

5. Secondary depression caused by medication

If some hypertensive patients take antihypertensive drugs, they may experience persistent depression and depression.

6. Secondary depression caused by physical illness

Diseases such as heart disease, lung disease, endocrine and metabolic disorders, as well as severe colds and high fever, can all trigger this type of depression.

7. Postpartum depression

Strong guilt, inferiority complex (especially when rural women give birth to baby girls and are discriminated against by their mother-in-law or husband), hatred, lack of love or disgust towards their babies, as well as crying, insomnia, decreased appetite, depression, etc., are common symptoms of this type of depression patients.

epidemiology
contagious
Non infectious.

incidence rate
In 2019, according to The Lancet, the lifetime prevalence of depression was 3.9%, with a December prevalence of 2.3%; According to survey data in China, the lifetime prevalence of depression has reached 6.8%; The 2022 National Depression Blue Book shows that the prevalence of depression among Chinese adolescents is 15% to 20%.

Easy to reach people
The average age of onset is 20-30 years old, and the incidence rate in females is higher than that in males (about 2:1).

Easy season
Good in autumn and winter.

cause of disease
executive summary
The etiology and pathogenesis of depression are still unclear, and a large amount of research data suggests that genetic factors, neurobiochemical, neuroendocrine, neuroimaging, neurophysiological, and psychosocial factors have a significant impact on the occurrence of this disease.

underlying cause

1. Genetic factors

Genetic factors are one of the important factors in the occurrence of depression. The risk of first-degree relatives of patients with depression developing depression is approximately 2-10 times higher than that of the general population, with a heritability of 31% to 42%.

2. Neurobiochemistry

There are three main neurotransmitter systems in the human brain, namely the noradrenergic, dopaminergic, and 5-hydroxytryptaminergic neurotransmitter systems, all of which play important roles in the onset of depression. In addition, other neurotransmitters such as adrenaline, acetylcholine, histamine, gamma aminobutyric acid, etc. are also closely related to the onset of depression. Research has found that depression is not only related to abnormal levels of neurotransmitters in the body, but also to changes in corresponding receptor function. Long term abnormalities in neurotransmitters can cause adaptive changes in receptor function, which not only affect the number and density of receptors themselves, but also affect post receptor signal transduction function and even affect gene transcription processes.

3. Neuroendocrine system

(1) The hypothalamic pituitary adrenal axis function of patients with depression is abnormal, manifested by increased cortisol levels in the blood, changes in the circadian rhythm of stress-related hormone secretion, and no spontaneous inhibition of cortisol secretion at night. Abnormal levels of adrenal cortex hormones may provide a neurobiological basis for diseases, on which genetic factors, life events, and stress interact. Repetitive life stress, especially stress starting from early life, can lead to high pituitary adrenal reactivity, slow elevation of corticosteroid levels, and a series of molecular level abnormalities, causing adverse effects on the central nervous system in terms of function and structure.

(2) The hypothalamic pituitary thyroid axis may also be involved in the pathogenesis of depression, based mainly on changes in the secretion rhythm of related hormones. In clinical practice, patients with hypothyroidism may also experience depressive symptoms such as depression, fatigue, and decreased energy. However, the causal relationship and pathophysiological basis between thyroid dysfunction and depression are still unclear. In addition, growth hormone, prolactin, melatonin, and sex hormones can also show varying degrees of secretion changes in patients with depression, and their roles in the onset of depression need further clarification.

4. Neuroimaging

With the development and popularization of magnetic resonance imaging (MRI) technology, there are more and more reports on the brain structure and functional imaging of depression. Currently, the most consistent findings mainly involve two neural circuits. One is the implicit emotion regulation circuit centered on the amygdala and medial prefrontal cortex, including the hippocampus, ventromedial prefrontal cortex, anterior cingulate cortex, anterior cingulate cortex, dorsal prefrontal cortex, etc. This circuit is mainly regulated by 5-HT; The second is the reward neural circuit centered on the ventral striatum/nucleus accumbens and medial prefrontal cortex, which is mainly regulated by dopamine. Both circuits in patients with depression exhibit abnormalities in neurotransmitter concentration, response to negative/positive stimuli, resting functional connectivity, white matter nerve fibers, gray matter volume, brain metabolism, and may involve different clinical symptoms in patients with depression. In addition, neuroimaging techniques such as positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance spectroscopy (MRS) have also provided evidence of abnormal biochemical metabolism in the brain of depression.

5. Neurophysiology

The research methods of neurophysiology include electroencephalography (EEG), brain evoked potentials (BEP), etc. Research on EEG of patients with depression has found a negative correlation between the severity of depression and the average integrated amplitude of their left and right hemispheres. In addition, EEG abnormalities in patients with depression exhibit lateralization, showing an increase in the activation level of the right hemisphere, mainly manifested as a relative decrease in alpha waves in the right hemisphere, a decrease in the right/left ratio of alpha waves, and a relative increase in the amplitude of fast waves in the right hemisphere. This increase in activation level is mainly manifested in the frontal region, mainly in the right frontal lobe, and is believed to be related to the development of depressive emotions. Patients with depression may also experience changes in BEP. During a depressive episode, the amplitude of BEP is small and correlated with the severity of depression, accompanied by prolonged latency of event-related potentials (ERP) P300 and N400.

6. Psychological and social factors

Generally speaking, stressful events in life such as the loss of loved ones, poor marital relationships, unemployment, and serious physical illnesses can all lead to the occurrence of depression. If multiple serious adverse life events coexist, they may synergistically affect the occurrence of depression.

Risk factors

1. Gender: The incidence of depression in women is twice that of men, and factors that increase the risk of depression in women include birth control and pregnancy, conflicts between work and child rearing, marital conflicts, sexual abuse, physical abuse, and poverty.
2. Age: The onset age of depression is mostly between 21 and 50 years old, with an average of around 30 years old. In recent years, there has been a trend of younger onset of depression.
3. Race: There are racial differences in the onset of depression, which are often accompanied by economic impacts.
4. Socioeconomic status: Generally speaking, individuals from lower social classes have a higher risk of developing severe depression compared to those from higher social classes, and the risk is higher in urban areas than in rural areas.
5. Personality traits: Individuals with obvious traits such as anxiety, compulsion, and impulsivity are prone to developing depression.
6. Social environment: The incidence rate of married people is low, but the incidence rate will increase greatly after divorce. Some negative life events can trigger the occurrence of depression, such as widowhood, unhappy marriage, unemployment, etc.
7. Physical factors: patients with malignant tumors, hypothyroidism, diabetes, coronary heart disease, rheumatic heart disease, Parkinson’s disease, epilepsy, stroke, autoimmune diseases, peptic ulcer, chronic kidney disease, AIDS, chronic pain and other diseases often lead to depression or depression.
8. The abuse and dependence of psychoactive substances: The abuse and dependence of some psychoactive substances can become risk factors for depression, such as opioids, alcohol, and sedative hypnotic drugs. A survey found that more than half of long-term drinkers experience depression.
9. Drug factors: Some drugs can become risk factors for depression, including synthetic steroids, corticosteroids, digitalis, anti Parkinson’s disease drugs (such as levodopa), antipsychotic drugs (such as chlorpromazine), antiepileptic drugs (such as sodium valproate, phenytoin, etc.), anti tuberculosis drugs (such as isoniazid traps), antihypertensive drugs (such as clonidine, levodopa, etc.), and anti-tumor drugs. Under conventional treatment doses, these drugs can cause some patients to experience depressive emotions or exacerbate symptoms of depression.

symptom
executive summary
The clinical symptoms of depression are very diverse, including low mood, thinking disorders, decreased willpower, cognitive impairment, and physical symptoms, and may also present with some atypical manifestations.

Typical Symptoms

1. Low mood

Low mood is the core symptom of depression, mainly manifested as significant and persistent emotional depression and pessimism. Mild depression patients may feel depressed or stressed; Patients with severe depression may feel pessimistic, hopeless, and unable to sense the meaning of life. Some patients may experience a depressive mood that is more severe in the morning and less severe in the evening, which can help with diagnosis. Clinically, patients usually sit with their heads down, remain silent, or cry due to inner pain; But a small number of patients may suppress their inner pain, smile during conversations, and exhibit “smiling depression”, which is easily misdiagnosed. These patients have a high risk of suicide.

2. Thinking disorders

The main manifestations are cognitive association disorders and cognitive content disorders.

(1) Mind association disorder: Patients often feel inhibited in their thinking, have difficulty considering and associating, and have obvious problems with insufficient brain capacity. Patients may also feel speechless when talking to others, manifested as slow thinking, slow response, difficulty answering, and in severe cases, they may even be unable to communicate with others.

(2) Mind content disorder: Patients with depression tend to have pessimistic and negative thinking content, which is significantly related to their depressive emotions. The patient has a low self-evaluation, feels worthless, has a pessimistic attitude, and feels uncertain about the future. In severe cases, patients may also suspect illness due to physical discomfort, such as suspecting that they have cancer. Some patients may also experience auditory hallucinations, and they may inexplicably blame themselves, believing that their presence has influenced others, leading to suicidal thoughts.

3. Reduced willpower activity

The volitional activity of patients with depression is significantly and persistently suppressed, clinically manifested as laziness, delayed behavior, estrangement from family and friends, avoidance of contact and interaction with others, or staying in bed all day, not wanting to work or go out, and unwilling to participate in activities they used to enjoy. In severe cases, patients may not eat or drink, or even speak or move, and develop into a state of stiffness (“depressive stiffness”).

4. Cognitive impairment

The cognitive impairment of patients with depression is mainly manifested as memory abnormalities, including decreased memory and increased negative memory, such as forgetting what just happened or only remembering pessimistic and negative things. Patients may also have attention disorders, such as decreased attention and long reaction times, as well as decreased abstract thinking and learning abilities. Cognitive impairment mainly affects patients’ social function and long-term prognosis.

5. Physical symptoms

This type of symptom is more common during depressive episodes, and patients’ symptoms may involve various organs, including sleep disorders, fatigue, decreased appetite, weight loss, constipation, pain (in any part of the body), decreased libido, erectile dysfunction, amenorrhea, and autonomic dysfunction symptoms. However, the depressive symptoms of some patients with depression may be masked by physical symptoms, known as “hidden depression”.

6. Other atypical manifestations of depression

Patients with depression may also experience personality disintegration, reality disintegration, and obsessive-compulsive symptoms. Personality disintegration is manifested as an increase in patients’ self attention, feeling that all or part of themselves seem distant or false, and often self denying. When reality disintegrates, patients may feel that their surrounding environment becomes unreal and unfamiliar, viewing things around them like watching a movie and feeling like they are in a dream. The patient’s compulsive symptoms are mainly characterized by compulsive thinking, always thinking about some bad things.

7. Symptoms of depression in special populations

(1) Depression in elderly patients: often accompanied by obvious anxiety, irritability, and sometimes irritability and hostility. Compared with young patients, their feelings of psychomotor inhibition and physical discomfort are more pronounced. Gastrointestinal symptoms such as decreased appetite, bloating, and constipation are often present in complaints of physical discomfort, and are often entangled in specific physical complaints; It is easy to develop the concept of suspicion and develop into suspicion, emptiness, and delusions of guilt. The course of illness for elderly patients is relatively lengthy and prone to becoming chronic.

(2) Childhood depression: Clinical manifestations mainly include low mood, lack of interest, low self-evaluation, self blame, self blame, and a sense of worthlessness. May be accompanied by delayed reactions, reduced speech and movement, unwillingness to play with children, loneliness, and may also lead to decreased appetite, fatigue, and sleep disorders.

(3) Perinatal depression: Perinatal depression often occurs during pregnancy and within 4 weeks postpartum, and can be diagnosed by meeting the diagnostic criteria for depression. Generally speaking, the proportion of perinatal depression during pregnancy and postpartum period is equally high.

complication
Generally, there are no obvious complications, but some patients may have accompanying mental and psychological problems such as anxiety.