The term mental illness clearly indicates that there is a problem with the mind. But is it just the mind in an abstract sense, or is there a physical basis to mental illness? As scientists continue to investigate mental illnesses and their causes, they learn more and more about how the biological processes that make the brain work are changed when a person has a mental illness.
Before thinking about the problems that occur in the brain when someone has a mental illness, it is helpful to think about how the brain functions normally. The brain is an incredibly complex organ. It makes up only 2 percent of our body weight, but it consumes 20 percent of the oxygen we breathe and 20 percent of the energy we take in. It controls virtually everything we as humans experience, including movement,
sensing our environment, regulating our involuntary body processes such as breathing, and controlling our emotions. Hundreds of thousands of chemical reactions occur every second in the brain; those reactions underlie the thoughts, actions, and behaviors with which we respond to environmental stimuli. In short, the brain dictates the internal processes and behaviors that allow us to survive.
How does the brain take in all this information, process it, and cause a response? The basic functional unit of the brain is the neuron. A neuron is a specialized cell that can
produce different actions because of its precise connections with other neurons, sensory receptors, and muscle cells.
The nervous system uses a variety of neurotransmitter molecules, but each neuron specializes in the synthesis and secretion of a single type of neurotransmitter. Some of the predominant neurotransmitters in the brain include glutamate, GABA, serotonin,
dopamine, and norepinephrine. Each of these neurotransmitters has a specific distribution and function in the brain.
Mental health professionals base their diagnosis and treatment of mental illness on the symptoms that a person exhibits. The goal for these professionals in treating a patient is to relieve the symptoms that are interfering with the person’s life so that the person can function well. Research scientists, on the other hand, have a different goal. They want to learn about the chemical or structural changes that occur in the brain when someone has a mental illness. If scientists can determine what happens in the brain, they can use that knowledge to develop better treatments or find a cure.
The techniques that scientists use to investigate the brain depend on the questions they are asking. For some questions, scientists use molecular or biochemical methods to investigate specific genes or proteins in the neurons. For other questions, scientists want to visualize changes in the brain so that they can learn more about how the activity or structure of the brain changes. Historically, scientists could examine brains only after death, but new imaging procedures enable scientists to study the brain in living animals, including humans. It is important to realize that these brain imaging techniques are not used for diagnosing mental illness. Mental illnesses are diagnosed by the set of symptoms that an individual exhibits. The imaging techniques would not enable the mental health professional to diagnose or treat the patient more effectively.
Some of the techniques are also invasive and expose patients to small amounts of radiation. Research studies using these tests are generally not conducted with children or adolescents.
One extensively used technique to study brain activity and how mental illness changes the brain is positron emission tomography (PET). PET scans can answer a variety of
questions about brain function, including where the neurons are most active. Scientists can use PET to measure changes in the activity of specific brain areas in a person who has a mental illness. Scientists can also investigate how the mentally ill brain changes after a person receives treatment.
PET imaging is not the only technique that researchers use to investigate how mental illness changes the brain. Different techniques provide different information to scientists. Another important technique is magnetic resonance imaging (MRI).
Unlike PET, which reveals changes in activity level, MRI is used to look at structural changes in the brain. For example, MRI studies reveal that the ventricles, or spaces within the brain, are larger in individuals who have schizophrenia compared with those of healthy individuals.
Other techniques that scientists use to investigate function in the living brain include single photon emission computed tomography (SPECT),functional magnetic resonance imaging (fMRI), and electroencephalography (EEG). Each technique has its own
advantages, and each provides different information about brain structure and function. Scientists often use more than one technique when conducting their research.
Causes of Mental Illness
At this time, scientists do not have a complete understanding of what causes mental illnesses. If you think about the structural and organizational complexity of the brain
together with the complexity of effects that mental illnesses have on thoughts, feelings, and behaviors, it is hardly surprising that figuring out the causes of mental illnesses is a daunting task. The fields of neuroscience, psychiatry, and psychology address different aspects of the relationship between the biology of the brain and individuals’
behaviors, thoughts, and feelings, and how their actions sometimes get out of control. Through this multidisciplinary research, scientists are trying to find the causes of mental illnesses. Once scientists can determine the causes of a mental illness, they can use that knowledge to develop new treatments or to find a cure.
Most scientists believe that mental illnesses result from problems with the communication between neurons in the brain (neurotransmission). For example,
the level of the neurotransmitter serotonin is lower in individuals who have depression. This finding led to the development of certain medications for the illness. Selective serotonin reuptake inhibitors (SSRIs) work by reducing the amount of serotonin that is taken back into the presynaptic neuron. This leads to an increase in the amount of serotonin available in the synaptic space for binding to the receptor on the postsynaptic neuron. Changes in other neurotransmitters (inaddition to serotonin) may occur in depression, thus adding to the complexity of the cause underlying the disease.
Scientists believe that there may be disruptions in the neurotransmitters dopamine, glutamate, and norepinephrine in individuals who have schizophrenia. One indication that dopamine might be an important neurotransmitter in schizophrenia comes from the observation that cocaine addicts sometimes show symptoms similar to schizophrenia. Cocaine acts on dopamine-containing neurons in the brain to increase the amount of dopamine in the synapse.
Risk Factors for Mental Illness
Although scientists at this time do not know the causes of mental illnesses, they have identified factors that put individuals at risk. Some of these factors are environmental, some are genetic, and some are social. In fact, all these factors most likely combine to influence whether someone becomes mentally ill. Genetic, environmental, and social factors interact to influence whether someone becomes mentally ill.
Environmental factors such as head injury, poor nutrition, and exposure to toxins (including lead and tobacco smoke) can increase the likelihood of developing a mental illness.
Genes also play a role in determining whether someone develops a mental illness. The illnesses that are most likely to have a genetic component include autism, bipolar disorder, schizophrenia, and ADHD. For example, the observation that children with ADHD are much more likely to have a sibling or parent with ADHD supports a role for genetics in determining whether someone is at risk for ADHD. In studies of twins, ADHD is significantly more likely to be present in an identical twin than a fraternal
twin. The same can be said for schizophrenia and depression. Mental illnesses are not triggered by a change in a single gene; scientists believe that the interaction of several genes may trigger mental illness. Furthermore, the combination of genetic, environmental, and social factors might determine whether a case of mental illness is mild or severe.
Social factors also present risks and can harm an individual’s, especially a child’s, mental health. Social factors include:
•Severe parental discord,
•Death of a family member or close friend,
•Parent’s mental illness,
•Exposure to violence.
Treating Mental Illness
At this time, most mental illnesses cannot be cured, but they can usually be treated effectively to minimize the symptoms and allow the individual to function in work, school, or social environments. To begin treatment, an individual needs to see a qualified mental health professional. The first thing that the doctor or other mental health professional will do is speak with the individual to find out more about his or her symptoms, how long the symptoms have lasted, and how the person’s life is being affected. The physician will also do a physical examination to determine whether
there are other health problems. For example, some symptoms (such as emotional swings) can be caused by neurological or hormonal problems associated with chronic illnesses such as heart disease, or they can be a side effect of certain medications.
After the individual’s overall health is evaluated and the condition diagnosed, the doctor and/or health practitioner will develop a treatment plan. Treatment can involve both medications and psychotherapy, depending on the disease and its severity.
Medications are often used to treat mental illnesses. Through television commercials and magazine advertisements, we are becoming more aware of those medications. To become fully effective, medications for treating mental illness must be taken for a few days or a few weeks. When a patient begins taking medication, it is important for a doctor to monitor the patient’s health. If the medication causes undesirable side effects, the doctor may change the dose or switch to a different medication that produces fewer side effects. If the medication does not relieve the symptoms, the doctor may prescribe a different medication.
Sometimes, individuals who have a mental illness do not want to take their medications because of the side effects. It is important to remember that all medications have both positive and negative effects. For example, antibiotics have revolutionized treatment for some bacterial diseases. However, antibiotics often affect beneficial bacteria in the human body, leading to side effects such as nausea and diarrhea. Psychiatric drugs, like other medications, can alleviate symptoms of mental illness but can also produce unwanted side effects. People, who take a medication to treat an illness, whether it is a mental illness or another disease, should work with their doctors to understand what medication they are taking, why they are taking it, how to take it, and what side effects to watch for.
Occasionally, the media reports stories in which the side effects of a psychiatric medication are tied to a potentially serious consequence, such as suicide. In these cases, it is usually very difficult to determine how much suicidal behavior was due to the mental disorder and what the role of the medication might have been. Medications for treating mental illness can, like other medications, have side effects. The psychiatrist or physician can usually adjust the dose or change the medication to alleviate side effects.
Psychotherapy is a treatment method in which a mental health professional (psychiatrist, psychologist, social worker or other mental health professional) and the patient discuss problems and feelings. This discussion helps patients understand the basis of their problems and find solutions. Psychotherapy may take different forms. The therapy can help patients:
•Change thought or behavior patterns,
•Understand how past experiences influence current behaviors,
•Solve other problems in specific ways, or
•Learn illness self-management skills.
Psychotherapy may occur between a therapist and an individual; a therapist and an individual and his or her family members; or a therapist and a group. Often, treatment for mental illness is most successful when psychotherapy is used in combination with
medications. For severe mental illnesses, medication relieves the symptoms and psychotherapy helps individuals cope with their illness.
Just as there are no medications that can instantly cure mental illnesses, psychotherapy is not a one-time event. The amount of time a person spends in psychotherapy can range from a few visits to a few years, depending on the nature of the illness or problem and the treatment model used.