The Hardest Mental Illnesses to Treat

Hardest Mental Illness to Treat

Mental health disorders fall across a broad spectrum, ranging from barely discernible to profoundly disruptive. The answer to the question of what is the hardest mental illness to live with isn’t straightforward. Understanding the most common mental disorders and the challenges associated with treating them can empower individuals to get the help they need.

The Hardest Mental Illnesses to Treat


Depression is a mood disorder that’s associated with ongoing feelings of sadness, numbness, loss of motivation, and feelings of worthlessness. It’s a common mental illness that, the Anxiety & Depression Association of America reports, affects nearly seven percent of the adult population in the United States.

While depression is commonly attributed to chemical imbalances in the brain, its cause is far more complex than simply having too much of one hormone or not enough of another. Research indicates that depression has many possible causes, including genetics, environmental stressors, faulty mood regulation, and diet and sleep patterns.

What Makes It Difficult to Treat?

Depression is difficult to treat for several reasons. First, depression can be very isolating and its symptoms tend to be hard to recognize. It’s what therapists may refer to as an internalizing disorder, meaning that the behaviors are directed inward. It’s easier to identify a disorder with externalizing behaviors such as hostility or aggression, but internalizing behaviors are less disruptive and therefore less noticeable. Without routine screening, depression can be easy to miss.

Second, because of the nature of depression, those living with it are much less likely to seek treatment. Depression can be a drain on someone’s motivation and energy levels, making it hard to proactively seek treatment and regularly attend therapy sessions.

Finally, depression can present differently in different people. In a small study that included a little fewer than 200 women with clinical depression, only 11 percent reported psychiatric problems as their main complaint, and less than half reported experiencing any psychiatric problems. Most women reported chronic pain, headaches, or sleep problems. This can make it difficult to get an accurate diagnosis, which is the first step in putting together a successful treatment plan.

Why It’s Important to Treat

Without treatment, the individual is more vulnerable to physical health issues such as muscle pain, digestive issues, and sleep loss. They’re also more likely to self-medicate with drugs or alcohol, leading to even more significant physical and mental health problems.

Depression rarely resolves on its own. While it’s generally considered to be a lifelong condition, there are effective treatments that can significantly improve the individual’s quality of life.


Anxiety disorders are the most common mental illness in the United States. It’s estimated that nearly one in five adults in the country have an anxiety disorder. While occasional anxiety is a part of life, those with anxiety disorders live in a near-constant state of worry and fear about everyday situations. This can be very disruptive, causing the individual to avoid everyday activities. Common symptoms of anxiety include feelings of nervousness, having a sense of impending danger, difficulty concentrating, and digestive problems.

What Makes It Difficult to Treat?

Unfortunately, only a third of those with anxiety ever receive treatment. Of those who get treatment, about 60 percent report an improvement in their symptoms.

Anxiety is difficult to treat primarily because it’s an essential part of our genetic makeup. Nature doesn’t select for traits that make people happiest—it selects for traits that keep them alive. People are hardwired to see how certain situations could be dangerous, a predisposition that can be difficult to overcome.

Anxiety is also difficult to treat because those with this disorder may be more likely to be high achievers who prefer to tackle problems on their own. These people may be less inclined to contact a mental health care professional for help with their symptoms.

Why It’s Important to Treat

Despite the challenges with treating anxiety, effective options are available. This typically includes a combination of medication and talk therapy. Treating anxiety can help individuals prevent complications such as the avoidance that may come after recurring panic attacks. Avoidance can make it difficult for individuals to manage family and work obligations as well as other necessary tasks. Untreated anxiety is also associated with an increased risk of depression and substance abuse. By accessing treatment for anxiety, individuals can learn healthy ways of managing their symptoms and coping with intrusive thoughts and panic attacks.


Schizophrenia is a serious mental disorder that causes individuals to perceive reality differently. They may experience visual and auditory hallucinations, delusions, and disordered thinking. In some cases, these can be very disabling, impacting the individual’s ability to lead a normal life. It’s estimated that about one percent of the population has schizophrenia, and only about a third of people with this disorder get treatment. Even so, people with a schizophrenia diagnosis account for about half of the residents in mental hospitals. They also account for an estimated 25 percent of the unhoused population in the United States.

What Makes It Difficult to Treat?

Schizophrenia is difficult to treat because of the different symptoms attached to the disease as well as the side effects of the medications commonly used to manage it. Symptoms manifest differently from one person to the next. While some people have the delusions and hallucinations most commonly associated with schizophrenia, other individuals have less obvious symptoms such as social withdrawal, lack of emotion, or enjoyment in activities or inability to respond to prompts. Individuals with this disorder may not recognize that they have a mental disorder that requires medical attention. Schizophrenia may co-occur with paranoia, depression and impaired motor function, further complicating an accurate diagnosis.

Additionally, while antipsychotics are often effective in controlling the symptoms of schizophrenia, this class of drugs works by changing the way brain chemicals behave. This is necessary for managing delusions and hallucinations. However, it also comes with unpleasant side effects such as nausea, weight gain, vision disturbances, and dizziness. These can be difficult to cope with, making it difficult for individuals to comply with their treatment plan.

Why It’s Important to Treat

Over time, schizophrenia causes a loss in brain volume, particularly in the areas involved with storing memories. Treating schizophrenia as early as possible can decrease the risk of loss and prevent further impairment. Effective treatment can also improve the quality of life for those with this disorder, helping them maintain steady employment and social connections.

Personality Disorders

Personality disorders are abnormal patterns of thought and behaviors that can make it difficult for the individual to function normally. There are 10 common personality disorders, each with its own symptoms and treatment options, including:

  • Antisocial personality disorder
  • Avoidant personality disorder
  • Borderline personality disorder
  • Dependent personality disorder
  • Histrionic personality disorder
  • Narcissistic personality disorder
  • Obsessive-compulsive personality disorder
  • Paranoid personality disorder
  • Schizoid personality disorder
  • Schizotypal personality disorder

It’s estimated that nearly one in 10 individuals are living with a personality disorder.

What Makes It Difficult to Treat?

Personality disorders are very difficult to treat simply because oftentimes, the nature of the disorder causes the individual to believe that there’s nothing to treat. Additionally, personality disorders are believed to be caused by a combination of genetics and early experiences, making them deeply ingrained in how the individual thinks and functions.

Why It’s Important to Treat

Fortunately, treatment for personality disorders is generally very effective. Targeted treatments such as social skills training, behavioral therapy, and treating co-occurring conditions such as anxiety and depression can help the individual achieve an improved quality of life.

Which Is the Most Difficult Mental Illness to Treat?

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, or DSM IV, contains approximately 297 disorders. These disorders range in severity, so while some people experience significant symptoms that require professional intervention, others can easily manage their symptoms on their own.

Ultimately, the worst mental disorder is the one that goes untreated. Rather than basing the severity of a disorder based on its classification, it’s important to consider each case individually based on symptoms as well as social and economic factors, medical history, and quality of life.

At FHE, we specialize in treating a full spectrum of mental illnesses and personality disorders. To learn more about our treatment options, contact us today.