The Link Between Depression and Other Mental Illnesses

Last Editorial Review: 11/28/2005
The Cleveland Clinic

Depression can be triggered by other mental illnesses, but it can also lead to certain mental illnesses. These include anxiety disorders , schizophrenia, eating disorders and substance abuse. Together, these conditions affect millions of Americans each year. Fortunately, they can be treated effectively -- allowing those affected to lead normal and productive lives.

Anxiety Disorders

Anxiety disorders produce an intense, often unrealistic and excessive state of apprehension and fear. They can occur during a given situation, or in anticipation of a particular situation occurring. When anxiety strikes, a person's blood pressure may rise, his or her heart races and breathing becomes more rapid. The person may also feel nauseated and experience other signs of agitation and discomfort. The causes of anxiety are as individual as the people affected, and the symptoms vary widely in degree.

Anxiety disorders will affect close to 25 million people at some time in their lives, affecting women twice as frequently as men. Some of the most common anxiety disorders are: Panic disorder , social phobia, agoraphobia, posttraumatic stress disorder , obsessive-compulsive disorder and generalized anxiety disorder .

Panic Disorder

One of the most common anxiety disorders is panic disorder . It is often present with depression and affects 2.5 million Americans every year, most often young adults. Panic disorder is periodic attacks of anxiety or terror, often unexpectedly and without reason. In general, the attacks last 15 to 30 minutes. It is common for the attacks to occur in a public place such as a restaurant or mall. The frequency of panic attacks vary -- for some people it may happen every week, while for others it may occur every few months. Because there seems to be no obvious explanation for why a panic attack starts, the fear of having another one is common and can affect the way a person lives. For example, if the attack occurs in a mall, then the person may stop going to the mall to avoid having another attack. This can lead to avoiding other large public places. It is not uncommon for attacks to trigger phobias of places or situations in which they have occured.

For somebody to be diagnosed with panic attack, they must have at least four of the following symptoms:

  • Fast heart beat
  • Extreme sweating
  • Shortness of breath
  • Shakiness
  • A choking sensation
  • Dizziness
  • Nausea
  • Numbness
  • Hot flashes/chills
  • Chest pain
  • Fear of dying
  • Feeling of losing control
  • Feelings of unreality or being detached from oneself

These symptoms are often accompanied by concern about having other attacks, worry over the implications of the attack (like fear of death from a heart attack) and altered behavior (like avoiding a particular place) because of the attack.

Social Phobia

Also known as social anxiety, this disorder is associated with excessive self-consciousness in social situations. These situations can range from public speaking, to signing one's name in front of people, to eating in a restaurant. Whatever the case may be, for those people who suffer from social phobia, these situations create an intense and constant feeling of being watched, judged and negatively evaluated. This intense fear of public humiliation often forces those affected by social phobia to go out of their way to avoid these types of situations, which can have a negative affect on their personal and professional lives.

Social phobia is a common disorder, affecting over 5 million people in a given year. It often begins in childhood and rarely develops after age 25. People with social phobia are often aware that their fears are irrational but are unable to lessen or erase these fears.

The symptoms of social phobia are much the same as they are for other anxiety disorders, and include trembling or shaking, intense sweating, nausea, difficulty talking, dry mouth and a racing heart. Like other anxiety illnesses these symptoms range from being mild and tolerable to so severe that they become socially debilitating.

Social anxiety is often treated with a combination of medication and talk therapy.


Depression is a(n) __________ . See Answer

Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is an anxiety disorder characterized by intense, recurrent, unwanted thoughts and rituals that are beyond the person's control. Examples of these rituals can include hand washing, counting, checking, hoarding, repeating, cleaning and the endless rearranging of objects in order to ensure they are in precise alignment. To the person affected, these rituals and thoughts are recognized as senseless and distressing, but extremely difficult to control. If the person does not perform these rituals, anxiety increases dramatically and the person becomes concerned that something terrible will happen because of his or her neglect.

While anxiety disorders generally affect women more often than men, OCD affects both genders equally. However, the degree to which OCD affects each person varies. For some it is mild, but for others, it can control their lives if left untreated. This disorder is typically first seen in adolescence or early childhood. OCD is sometimes accompanied not only by depression, but also eating disorders, substance abuse, attention deficit hyperactivity disorder(ADHD) and other anxiety disorders. OCD affects more than 3 million Americans in any given year.

Treatment is less straightforward for patients with OCD. Some patients benefit from medicines alone, while others only respond to behavior therapy.


Schizophrenia is a type of psychotic illness. A psychotic illness prevents people from being able to distinguish between the real and imaginary worlds. A person with schizophrenia experiences jumbled thoughts, images and sounds that come and go in phases, often suddenly and severely. Because the severity of schizophrenic episodes varies, some people can understand reality and function at work and at home, while others may be unable to function at all. Examples of schizophrenic symptoms include the following:

  • Hallucinations -- seeing, hearing, smelling or feeling things that aren't really there
  • Delusions -- false beliefs from which the person cannot be dissuaded
  • Inability to make sense out of the world
  • Emotions, thoughts, and moods that do not correspond to an event
  • Hyperactivity
  • Catatonia -- a set of symptoms that can vary from near motionlessness to abnormal purposeless movements
  • Speaking in sentences that do not make sense
  • Depression
  • Isolation from the outside world, including family and friends
  • Mood swings
  • Inability to function in school, work, or other activities
  • No longer washing or grooming oneself

In order to be diagnosed with schizophrenia, these symptoms generally must last at least six months. There is no one cause of schizophrenia, but it has been attributed to genetic changes and variations in brain chemicals. More recent studies have implicated defects in brain structure and how nerves are arranged in the brain. Schizophrenia does tend to run in families. While stress can aggravate the symptoms of schizophrenia, it is not the cause of this psychosis. Poor parenting and a bad upbringing have also been ruled out as causes.

Schizophrenia affects men and women equally, though it tends to affect men earlier (late teens to early 20s) than women (20s to early 30s). Over 2 million Americans are affected by schizophrenia in a given year.

The most common approach to treating patients with schizophrenia is prescribing antipsychotic drugs. These medicines can lessen or stop hallucinations, help patients distinguish between reality and the imaginary, and lessen feelings of confusion. Once use of the medicine stops, the symptoms often return.

Eating disorders

Eating disorders are poorly understood and typified by harmful eating habits. They are most common among teenage girls and women, and frequently occur along with other psychiatric disorders such as depression and anxiety disorders. Eating disorders often get worse the longer they go untreated. The lack of nutrition associated with eating disorders can harm the body's organs and, in severe cases, lead to death. The two most common types of eating disorders are anorexia nervosa and bulimia nervosa .

People with anorexia purposefully starve themselves, despite their hunger. They tend to be very good in sports, school, and work -- often seeking perfection. Some people with anorexia stop eating in order to gain a feeling of control over their lives, while others may do so to rebel against parents and other loved ones. The diagnosis of anorexia nervosa requires that a person weigh at least 15% less than his or her normal body weight. Symptoms associated with this illness include:

  • Rapid weight loss over several weeks or months
  • Dieting even though weight is already very low
  • Having an intense fear of gaining weight or getting fat
  • Believing that the body is fat when in reality it is not
  • Watching every bite of food
  • Eating in secret
  • Having an unusual interest in food
  • Exercising very often
  • Becoming very depressed or anxious
  • Infrequent or absent menstrual periods
  • Wearing loose clothing to hide weight loss
  • Wanting to be perfect or being highly self-critical

It is not uncommon for people with anorexia nervosa to purge, or empty themselves, through vomiting and abuse of laxatives, enemas and diuretics. Some physical signs of anorexia nervosa include a low tolerance to cold weather, brittle hair and nails, dry or yellowing skin, anemia, constipation and swollen joints.

Like other mental and emotional illnesses, the degree to which people suffer from anorexia varies. Some may recover fully after a single episode, while others spend years battling the illness. It is estimated that up to 3.7% of females will suffer from anorexia at some time during their lives.

For people suffering with bulimia nervosa, large amounts of food are eaten all at once and then vomited. The vomiting is triggered by a fear of weight gain or stomach pain. People with bulimia also use laxatives, diuretics and vigorous exercise to purge themselves. In order for a person to be diagnosed with bulimia, this behavior must occur at least twice a week for three months in a row. Although people with bulimia are often underweight, they may also appear to have a normal body weight. Common symptoms of bulimia include:

  • Fasting
  • Secrecy about eating behaviors
  • Frequent bathroom use after eating
  • Depression and mood swings
  • Chewing and spitting out foods
  • Preoccupation with food and weight
  • Irregular menstrual periods
  • Drug or alcohol abuse
  • Feelings of anxiousness
  • Intense feelings of guilt or shame

Because of frequent vomiting, people with bulimia expose themselves to higher than average amounts of stomach acid, which over time can lead to physical problems. These may include a sore or bleeding throat, stomach problems, heartburn, bloating, swollen glands in the cheeks and face and tooth decay. Though no one cause exists for bulimia, it is often a reaction to stress and anxiety. It is estimated bulimia will affect up to 4.2% of females at some point in their lives.

For patients with eating disorders, counseling is often an effective treatment. Counseling teaches patients how to free themselves from destructive patterns of thinking and behaving as well as re-evaluate their relationship with food. Medicines such as antidepressants may also be prescribed.

Substance Abuse

Substance abuse is the use of drugs or alcohol to the point of social, occupational or physical harm. Millions of Americans abuse drugs or alcohol for a variety of reasons -- including as a coping mechanism to stress and anxiety or due to biological factors, such as a genetic tendency. Commonly associated with depression, substance abuse may include some of the following symptoms:

  • The need to increase the amounts of a substance in order to become intoxicated or a diminished effect from continued use of the same amount.
  • Withdrawal symptoms such as nausea, shaking, insomnia, agitation, and sweating following a reduction in the amount of a substance taken.
  • In order to ease withdrawal symptoms, a person takes more of the substance.
  • Despite a person's efforts, discontinuing use of the substance is not possible.
  • Large amounts of time and effort are spent trying to get the substance or recover from its use.
  • The amount of a substance is increased over time, beyond any amount originally intended.
  • The substance is still used despite the knowledge of its harmful effects on a person's physical and mental condition.
  • Social, recreational and work-related activities are given up or reduced because of substance use.

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In treating patients with substance abuse, the approach may vary from person to person. Some respond well to one-on-one counseling, others to group counseling and support groups. Antidepressant medicines -- in combination with education to help patients address and conquer the emotions that cause them to abuse drugs or alcohol -- can also be very effective.

Reviewed by the doctors at The Cleveland Clinic Department of Psychiatry and Psychology.

Edited by Cynthia Haines, MD, WebMD, July 2005.

Portions of this page © The Cleveland Clinic 2000-2005

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