The 7 Most Common Mental Illnesses

The most common mental illnesses go far beyond depression and anxiety, and their consequences can be very significant. Here we tell you 7 of them.
The 7 Most Common Mental Illnesses
Samuel Antonio Sánchez Amador

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 18 June, 2023

Social and productive dynamics pose a real challenge to the human mind. Living in a globalized world demands productivity, effectiveness, the capacity for socialization, infinite responsibilities, and many more simultaneous tasks. It’s normal for the mind to suffer the effects of an unbridled vital rhythm, and therefore, the most common mental illnesses are becoming more and more common.

As indicated by the portal Communicates Mental Health, 1 in 4 people will have a disorder of this nature throughout their lives. What’s more, 12.5% of all global health problems are represented by mental illnesses, although between 35 and 50% of patients who suffer from them don’t receive any treatment (or this treatment is inadequate).

At this rate, we can predict that mental health problems will be the leading cause of disability in the world in 2030. The importance of publicizing and normalizing disorders of this type is self-explanatory, as only in this way will the thousands of people who suffer in silence be encouraged to seek help. Discover with us the 7 most common mental illnesses.

What is mental illness?

According to the World Health Organization (WHO), health is a state of complete physical, mental, and social well-being, and not just the absence of diseases or illnesses. Therefore, a person may not present a pathological picture and still not feel well, and therefore, be lacking in health.

At the same time, the same entity argues that a disease is the alteration or deviation of the physiological state in one or several parts of the body, for generally known causes, manifested by characteristic symptoms and signs, and whose evolution is more or less predictable. The brain is a part of the body, so a disorder in this organ is considered a disease.

This meaning is very important because, for certain sectors of the population, it’s difficult to understand that a condition without physical symptoms can be just as serious as heavy bleeding or a broken arm. A mental disorder is a pattern of behavior that causes significant distress or impaired personal functioning, and as such, requires care just like any other condition.

In general terms, mental illnesses manifest as alterations in reasoning processes, behavior, the ability to recognize reality, and in the possibility of managing emotions and relationships. As indicated by the statistical portal Our World in Data, 970 million people around the world suffer from some condition of this type.

Despite the high prevalence of these disorders, up to 50% of patients don’t receive the indicated treatment.

The 7 most common mental illnesses

Now that we’ve made it clear that mental disorders require attention in all cases, we can enter the clinical realm. Discover with us what the 7 most common mental illnesses in the world are.

1. Generalized anxiety disorder

A woman suffering from anxiety.
When anxiety occurs constantly and negatively affects the quality of life, it’s likely that generalized anxiety disorder has developed.

Anxiety at specific times is normal and even positive. When we detect a threat, the body releases adrenaline and cortisol, two of the hormones responsible for symptoms of acute and prolonged stress. In a state of alert, the human body shows an increase in heart rate, vasoconstriction, dilation of the airways, and mobilization of energy reserves.

In other words, anxiety helps us respond and fight more effectively. The problem comes when there’s no threat and the body gets used to a constant state of stress. As the Mayo Clinic indicates, this physiological imbalance can lead to depression, digestive problems, headaches, sleep problems, and many more conditions.

Generalized anxiety disorder (GAD) affects 5% of the population at any given time and place. This translates to 40 million people with this condition in the United States alone, although the actual numbers are estimated to be much higher. If you’ve had chronic anxiety symptoms for more than 6 months, don’t hesitate to go to a psychiatrist.

In generalized anxiety disorder (GAD), various symptoms appear at an interval of 6 months or more.

2. Depression

Depression is one of the most common mental illnesses in the world. As indicated by the World Health Organization (WHO), this condition (sometimes silent) affects 300 million people around the planet, or in other words, more than 5% of the population. In addition, between 70% and 80% of depressed people in low-income countries don’t receive treatment.

These data are very alarming, much more if we consider that up to 20% of untreated patients end up choosing suicide as a way out at some point in their life. The main recommendation is obvious: If you feel that something isn’t going well in your mind or in your environment, don’t hesitate to go to the psychiatrist. Not being well isn’t normal, no matter what you believe.

Some of the most common symptoms or sensations in patients with clinical depression are the following:

  • A continuous feeling of sadness
  • A feeling of lack of hope and of not being able to be helped
  • Low self-esteem
  • Feeling a constant or recurring urge to cry
  • An excessive presence of remorse
  • Intolerance and lack of motivation
  • Difficulty in making decisions
  • Am inability to experience joy in situations that should be stimulating

In addition to these psychological symptoms, there are physiological clinical signs that can be observed in some people with depressive conditions. Any of the cited symptoms indicate the need to see a psychiatric professional.

3. Phobias

A phobia is defined as an “anxiety disorder characterized by an intense, disproportionate, and irrational fear of a specific event or situation.” According to studies, this is one of the most common mental illnesses in the world, as its prevalence throughout life reaches up to 12.5% of the general population.

There are phobias toward many things: Insects (entomophobia), closed places (claustrophobia), the concept of death (thanatophobia), and spiders (arachnophobia) are just some examples. All of them are characterized by showing a significant increase in vegetative activation, avoidance/escape behaviors, the anticipation of catastrophic consequences, and thoughts of harm.

Exposure therapies mediated by a professional are usually very useful in these clinical pictures.

4. Alcohol use disorder

You may not have expected a disorder like this one on the list, but substance use disorders are mental illnesses after all. Dopaminergic circuits at the brain level are disrupted when a compound generates dependence, and therefore, the abuse of alcohol and other drugs can be perfectly included in the group of psychiatric disorders.

We’ll go further, as sources already cited define addictions as “chronic and recurrent diseases of the brain.” Alcoholism is the standard bearer in this category, as the harmful use of this substance is a causal factor in more than 200 disorders. Every year, there are 3 million deaths from the harmful use of alcohol, or in other words, 5.3% of all deaths.

Some symptoms of addiction (to alcohol or any other substance) are the following:

  • Taking the substance in much larger amounts than planned or for longer than planned
  • Continued use of the substance despite the knowledge of the damage it generates on the addict
  • Abandonment or reduction of social, occupational, or recreational activity due to substance use
  • Development of tolerance (the need to increase doses) and withdrawal (undesirable physical effects when leaving the substance)

Besides alcohol, we can mention other addictive substances, such as narcotics, opioids, nicotine, or marijuana. To date, the only activity that’s considered addictive per se beyond drugs is gambling.

5. Obsessive-compulsive disorder (OCD)

Obsessive-compulsive disorder (OCD) is a mental condition characterized by the presence of thoughts (obsessions) and rituals (compulsions) repeatedly over time. These clinical signs significantly interfere with the life of the patient and can’t be easily controlled or stopped.

The condition is observed in the same way in men and women, with a prevalence of 1% and 3% in adults and 1% and 2% in children and adolescents. As indicated by the NHS, its origin is believed to be multifactorial and includes both genetic and environmental predisposing factors. The course of OCD is chronic, but it can vary depending on the stress of the patient.

6. Anorexia

Anorexia nervosa, along with bulimia, forms the bulk of eating disorders (EDs), although they’re not the only ones. This condition is characterized by a rejection of food by the patient and an obsessive fear of gaining weight, which leads to a strict self-imposed restriction on food.

Some symptoms of anorexia are as follows:

  • An intense fear of gaining weight.
  • Distortion of body image. In other words, the patient feels very fat despite having an abnormally low body mass index (BMI).
  • A weight that’s below the expected average to the point of reaching malnutrition.
  • Physical signs: Rough skin, hair loss, menstrual irregularities, dizziness, fatigue, and much more.
  • Sadness, anguish, avoidance of social situations, and irritability.
  • Low self-esteem, sometimes caused by self-demands and perfectionism.

According to the medical journal Current Psychiatry Reports, the prevalence of anorexia nervosa is approximately 0.9% of adult women. Other studies are much less optimistic, indicating that 1 in 10 adolescent women in some regions suffers from some type of eating disorder.

As discouraging as it may seem, it’s important to report that anorexia is the mental illness with the highest mortality rate in the world, above schizophrenia and depression. Death usually occurs due to organic failure derived from low weight or suicide.

Treating anorexia requires years of constant psychological care. Most patients take several years to “get well” and many others never fully recover.

7. Personality disorders (PD)

Among the most common mental illnesses are personality disorders.
Identifying a personality disorder isn’t an easy task, especially for those affected themselves. Knowing these conditions is essential as the first step in seeking help.

Personality disorders are a set of disturbances that occur in emotional, affective, and motivational dimensions and in relation to the social environment. Patients with a disease of this type have problems with cognition, emotion, interpersonal functioning, or impulse control.

This group represents one of the most common mental illnesses in the world, as it encompasses between 40-60% of patients admitted to the psychiatric environment. Furthermore, they represent the most frequent diagnosis in this type of establishment.

There are many personality disorders (PD), classified into 3 groups: A (rare or eccentric disorders), B (dramatic, emotional, or erratic disorders), and C (anxious and fearful disorders). Some of the most representative are the following:

  • Schizoid Personality Disorder: The prevalence is estimated to be less than 1% of the population. People with this disorder are characterized by a lack of interest in socializing and by a restriction of emotional expression.
  • Borderline Personality Disorder: As indicated by professional sources, this disorder is characterized primarily by emotional instability, highly polarized thinking, impulsivity, and chaotic interpersonal relationships. Its prevalence is estimated at 0.2-1.8% of the general population.
  • Avoidant Personality Disorder: This disease is characterized by a generalized pattern of hypersensitivity to negative evaluation, rejection, or disapproval, and avoidance of social interaction.

All of these diseases require medical attention

There are many mental illnesses described so far. All the conditions that we’ve mentioned require a psychiatric evaluation, as they’re more or less serious and must be treated. This is especially important in the case of eating disorders (EDs) and depression.

Although the mortality rate is low for almost all of these diseases, many of them become disabling and can seriously hinder the patient’s life over time. If you’ve identified with any of the aforementioned symptoms, we advise you to go to a professional: You’re not alone and the help works.

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