Depression – it’s an increasingly common illness that doesn’t seem to offer any respite. The World Health Organization (WHO) estimates that at least 322 million people worldwide suffer from depression, up 18% from ten years ago. Also known as major depressive disorder, clinical depression is characterized by persistent feelings of sadness, loss of interest, cognitive impairment, and problems with sleep and appetite. It is a recurrent and costly disease that often becomes chronic, causing suffering and disability.
What causes depression? Unfortunately, we don’t know. However, there are many studies on its risk factors – the characteristics and circumstances that increase the likelihood of depression.
Some are common sense risk factors such as dramatic life events – the death of a loved one or the diagnosis of a serious illness. However, there are many other lesser-known but important risk factors. These include sociodemographic factors, genetic and neurological factors, personal factors, adverse experiences, and comorbidity.
Sociodemographic factors: twice as many women are depressed
Gender is perhaps the most consistent and well-known sociodemographic risk factor for depression. Regardless of country or culture, postpubescent women are twice as likely to suffer from depression as men.
However, researchers have identified other sociodemographic risk factors for depression such as age, marital status, education level and race. Depression occurs more frequently in white people, young adults, single adults, separated or divorced couples, and people with low levels of education. Depression is also more common among low-income, unemployed, and urban dwellers.
Genetic factors: depression can be hereditary
Immediate family members of patients with depression are three times more likely to develop the condition. Studies indicate that 26-42% of variations in depression are due to genetic influences. There is also evidence that early and recurrent depression is more likely to be hereditary. However, no specific gene or set of genes has been reliably associated with depression or parental inheritance – the disease is too heterogeneous.
Neurological factors: the amygdala becomes overactive
Neural abnormalities have been documented in certain brain regions of adults with depression. Specifically, they are structural abnormalities in the gray matter volumes of the hippocampus, amygdala, anterior cingulate cortex, and dorsolateral prefrontal cortex.
When we become depressed, neural function also changes. There is heightened brain activation in subcortical regions of emotion processing, such as the amygdala and limbic circuits, combined with dampened activation in regions of cognitive control.
This doesn’t just happen in adults. The same abnormalities in neural function and structure have been identified in children of parents with depression, even before the onset of a depressive episode. This is why experts believe that these children are more vulnerable to this disorder.
Personal factors: introversion and excessive self-criticism
A propensity for negative emotions (fear, anger, sadness and anxiety), as well as mood swings and negative thoughts – known as neuroticism – are personal factors that increase the risk of experiencing a depressive episode.
Introverts are also more likely to suffer from depression. They are individuals who prefer solitary activities and are more focused on their own thoughts, feelings, and moods than on seeking external stimuli.
Research also indicates that there is a relationship between depression and low levels of consciousness. This is characteristic of aimless, flippant, lazy, careless, undisciplined, and weak-willed individuals.
Excessive self-criticism (feelings of guilt and failure due to unrealistic self-expectations) and dependency/sociotropy (feeling of helplessness and fear of abandonment due to strong emotional dependence on others ) are also predictors of depression.
Another attitude that promotes depression is what is called the negative attribution style. It is the tendency to attribute negative experiences to internal, stable and global causes. For example, “I didn’t get the job because I’m useless and always have been.”
Something similar happens with mental rumination, which continually thinks the same sad or gloomy thoughts, which focuses attention on depressive symptoms and their implications, causes and meanings for oneself.
Finally, deficits in personal resources (social skills, appropriate problem-solving strategies, and coping skills under stressful circumstances) are also linked to an increased risk of depression.
Over 40 years of research has documented the role of traumatic life events in the onset of depression. Depending on the type of sample studied, approximately 50-80% of people with depression reported a traumatic or serious life event before the onset of the disorder.
We could reasonably say that people with depression are 2.5 times more likely to have experienced a serious life event before onset than those without depression. Typical traumatic life events include life-threatening health issues, separation and bereavement, exposure to violence, job loss, and financial insecurity.
Equally important are cataclysmic events or phenomena in which a single, sudden and powerful event affects a large number of people. These events are often beyond the control of any individual or group and are considered universally stressful, such as the Covid pandemic.
Negative childhood events also put us at risk for depression as we grow up. These include physical and sexual abuse, psychological neglect (or abandonment), exposure to domestic violence, parental mental illness, and criminality. People with a history of childhood trauma (particularly bullying and childhood emotional abuse or neglect) are more than twice as likely to develop depression.
One of the most striking aspects of depression is that it is often accompanied by other mental disorders, especially anxiety disorders, substance abuse disorders, eating disorders, and sleep problems.
Additionally, any chronic or severe medical condition can be a risk factor for depression. Depression has been shown to be associated with a wide range of physical illnesses: acute myocardial infarction, asthma, cancers, cardiac arrhythmia, chronic coronary syndrome, chronic obstructive pulmonary disease, congestive heart failure, certain neurological illnesses such as Alzheimer’s disease or epilepsy, thyroid problems. , diabetes, obesity, certain pathologies of the digestive system, hypertension, osteoarthritis, osteoporosis, kidney failure, rheumatoid arthritis, stroke, fibromyalgia, chronic fatigue, etc.
Recognizing all of these risk factors can help us better understand depression, prevent the onset of the disease, and perhaps slow its seemingly inexorable progression.