Psychopharmacology is the study of how psychotropic drugs affect a person's mental state and behavior. Over 100 billion neurons in the nervous system communicate with one another by releasing a chemical into the tiny spaces between two neurons, called synapses. This chemical is called a neurotransmitter. The neurotransmitter is released by the presynaptic neuron and binds to a receptor on the receiving neuron so the message can move along the nerve pathway. Thus almost all psychotropic drugs, or medications for the treatment of mental disorders, change how neurons communicate. These drugs can have various side effects, ranging from taste changes, memory loss, and frequent urination to muscle spasms, weight gain, tremors, and blurring of vision. Some psychotropic drugs are also addictive. A handful of neurotransmitters located within specific circuits of the brain are the targets of psychoactive drugs. The drugs either increase neural activity at synapses (agonists) or reduce it (antagonists).
Antipsychotic drugs for schizophrenia are known as neuroleptics, with the oldest sold under the brand name of Thorazine. These drugs gradually reduce symptoms such as mental confusion, hallucinations, and delusions by decreasing activity at certain dopamine synapses. A newer class of antipsychotics, atypical neuroleptics, were approved for use in the 1990s. These drugs influence the activity of two mood-related neurotransmitters (dopamine and serotonin). Both typical and atypical neuroleptic drugs have serious side effects, including sedation, weight gain, tremors (similar to those in Parkinson's disease), and tardive dyskinesia, a disorder characterized by repetitive bodily movements such as lip-smacking and grimacing. Movement-related side effects are often less severe for atypical neuroleptics. A third class of antipsychotics is under development, designed to target the neurotransmitter glutamate with fewer side effects.
Antianxiety drugs are often used to treat disorders that involve intense fear or chronic worry. The most common branded tranquilizers for anxiety, in the benzodiazepine family of drugs, are Xanax, Ativan, and Valium. Benzodiazepines target the neurotransmitter GABA (gamma amino butyric acid), which inhibits neural transmission. Benzodiazepines increase the efficiency of GABA, causing even greater inhibition or calming of the repetitive thought cycle producing anxiety. Because these medications are addictive and work only while people are taking the medication, treatment guidelines advise combining drug treatment for anxiety with cognitive-behavioral therapy. Withdrawal effects can include intense anxiety and panic attacks.Depression is treated with mood-elevating drugs. Older classes of antidepressants, discovered in the 1950s, are tricyclics and MAO inhibitors. These medications target dopamine, norepinephrine, and serotonin synapses. These medications are rarely used in the 21st century because they carry a risk of overdose and cause uncomfortable side effects. For example, tricyclics often cause weight gain, constipation, and blurred vision. MAO inhibitors can cause stomach distress, headaches, drowsiness, and life-threatening interactions with some foods and medications. A newer class of drugs, called selective serotonin reuptake inhibitors (SSRIs), are the most common medication for depression. SSRIs, including brand-name drugs such as Prozac, Paxil, Zoloft, and Celexa, slow the reuptake (reabsorption) process at serotonin synapses. By blocking the reuptake process, more serotonin becomes available to the brain. Over a period of weeks, making more serotonin available leads to changes in the brain that help regulate mood. Scientists still do not fully understand why antidepressants work.
How SSRIs Delay the Reabsorption of Serotonin
Common Categories of Drugs Used to Treat Psychological Disorders
|Categories of Therapeutic Drugs||Associated Disorders||Associated Neurotransmitters||Side Effects||Function||Commonly Used Drugs in This Category|
|Antipsychotic (neuroleptic)||Psychotic disorders||Dopamine
Serotonin (for atypical antipsychotics)
|Reduce hallucinations and delusions, decrease agitation||Typical antipsychotics
|Antianxiety (benzodiazepines)||Anxiety disorders||GABA||Sedation
Intense anxiety during withdrawal
|Reduce anxiety and unpleasant physical arousal||Xanax
|Selective serotonin reuptake inhibitors (SSRIs)||Mood and anxiety disorders||Serotonin||Headache
|Reduce sadness, irritability, and anxiety||Prozac
|Mood stabilizers||Bipolar disorders||Dopamine Serotonin||Feeling emotionally flat
|Reduce depression and mania (excessively elevated mood)||Lithium
Psychosurgery, ECT, and Brain Stimulation
Psychosurgery and electroconvulsive therapy (ECT), introduced as high-tech treatments for mental illness in the 20th century, have a notorious history. Psychosurgery alters the physical structure of the brain for the purpose of treating mental illness. For example, frontal lobotomies (operations severing parts of the prefrontal cortex) were still being performed in the 1970s. One famous lobotomy victim was Rosemary Kennedy, the sister of President John Kennedy. Her father agreed to the lobotomy to quell what he considered rebellious behavior. After the procedure, however, 23-year-old Rosemary was said to have the mental capacity of a two-year-old and was subsequently institutionalized. Lobotomies are generally no longer performed to treat mental illness. Psychosurgery is conducted today in rare cases, such as severe epilepsy that is unresponsive to other forms of treatment. Current procedures are much more precise than past psychosurgical measures.Electroconvulsive therapy (ECT) is a treatment for severe depression that involves triggering a brief seizure by passing a weak current through the patient's brain. Early versions of ECT were also forms of patient abuse, often leaving people with permanent brain and physical damage. However, ECT has been modified and began to be used judiciously in the 1980s for certain types of serious depression for which other types of treatment have proved ineffective. Before providing ECT, doctors give patients muscle relaxants and administer general anesthesia. Electrodes (sensors used to measure electrical conductivity) are attached to the scalp, and a series of electrical pulses are used to trigger a brief seizure or convulsion. Upon awakening, the person usually experiences some disorientation but often returns to normal in a matter of hours. The treatment is typically administered three times per week for 6–12 weeks, with maintenance treatments sometimes used to prevent symptom recurrence. ECT is generally administered on the right side of the brain, opposite the learning and memory areas, and is thus less likely to produce permanent memory loss. ECT can rapidly improve some cases of severe depression, mania, or catatonia (lack of movement).