There are four psychological diseases and disorders that biopsychology focuses on; these are schizophrenia, affective disorders, anxiety disorders, and Tourette syndrome. There are numerous theories that attempt to understand the causes of these disorders. Research has led to drug treatments that lessen the effects of the disorder or disease; however, all medications have negative side effects associated with them. (Pinel, 2007)
Schizophrenia
The primary issue with schizophrenia is symptom complexity; additionally, symptoms may change throughout disease progression. The most common symptoms of schizophrenia are: strange delusions, flat or inappropriate affect, auditory hallucinations, incoherent thoughts, and abnormal behaviors. Much of the causal factors that lead to schizophrenia are still in question. Recent research has led to the discovery that schizophrenia can be biologically inherited. The dopamine theory of schizophrenia began in the late 1950s with the discovery of the role dopamine plays in treatment. After many revisions, the current dopamine theory proposes that although over-activity at D2 receptors is significant in schizophrenia, other causal factors have yet to be identified. (Pinel, 2007)
Neuroleptic is the term given to antipsychotic medications that effect thought processes and behaviors (Challoner & Newton, 2008). Pinel (2007) highlights three medications used in the treatment of schizophrenia; they are chlorpromazine, haloperidol, and spiroperidol. The drug chlorpromazine is in the phenothiazines chemical class, which binds to D1 and D2 receptors. Haloperidol and spiroperidol are in the butyophenones chemical class, which binds to D2 receptors. Chlorpromazine lessens the severity of symptoms and reduces agitation or "activates" those experiencing flat or inappropriate emotional affect. Side effects are similar in nature to Parkinson's disease: a reduction in voluntary movement, rigid musculature, and tremors while resting. Clozapine is another medication used to treat schizophrenia. Clozapine is an atypical neuroleptic (meaning that is does not work mostly on D2 receptors); instead, clozapine works primarily on D1, D4, and serotonin receptors; hence, clozapine does not carry the Parkinson-like side effects. Clozapine is an effective treatment for schizophrenic patients who are unresponsive to typical neuroleptics. (Pinel, 2007)
Affective Disorders
Affective disorders are simply disorders that affect emotion. There are two main types of affective disorders: depression and mania. Depression is feelings of despair or the inability to experience happiness/pleasure; there are two types of depression: reactive depression (situational such as the loss of a loved one or job) and endogenous depression (no relational cause). Mania is the flip side of the depression coin and is marked by an overabundance of confidence, easily distracted, impulsive, and over-energized. Many persons who experience depression also have cyclic mania, referred to as bipolar affective disorder. Persons who experience persistent and repetitive bouts of depression are said to have unipolar affective disorder. (Pinel, 2007)
The cause of unipolar and bipolar affective disorders is much in debate. There are two primary theories about the cause of depression. The monoamine theory of depression proposes that depression is caused by a problem in the production, altercation, or release of the neurotransmitters serotonin and norepinephrine, if not both; this theory is based on the use and action of anti-depressant medications. The diathesis-stress model of depression proposes that there is a genetic vulnerability to depression, though unable to kick off depression on its own, the vulnerability is caused by early exposure to stress in childhood that causes a permanent susceptibility to depression triggering an individual to over-compensate during periods of mild stress. This theory is based on the overabundance of stress hormones that are released by depressed individuals. (Pinel, 2007)
There are four main types of antidepressant medications used in the treatment of affective disorders; they are lithium, tricyclic antidepressants, selective monoamine-reuptake inhibitors (SSRI), and monoamine oxidase inhibitors (MAOI). Lithium is a metallic ion that has been successfully used as a mood stabilizer in individuals with bipolar affective disorder; used mainly to treat mania, lithium has also shown to be effective in some bipolar patients at reducing depression. Tricyclic antidepressants block the reuptake of serotonin and norepinephrine, increasing the level of these neurochemicals in the brain. SSRIs block the reuptake of serotonin, and are purported to have very few side effects. MAOIs block the monoamine oxidase enzyme responsible for breaking down monoamine neurotransmitters in the neuron. Though initially purported to have mostly negligible side effects, MAOI side effects are now being called into question. (Pinel, 2007)
Anxiety Disorders
Anxiety is defined as feelings of fear, coupled with physiological reactions that interfere with activities of daily living and the ability to function normally in society. The five categories of anxiety disorders are generalized anxiety (no precursor), phobic anxiety (produced when exposed to specific objects or situations), panic (rapid-onset of fear coupled with extreme physiological signs of stress), obsessive-compulsive (frequent, persisitent, and uncontrollable thoughts and impulses), and posttraumatic stress disorders (recurring psychological stress after a trauma). Anxiety disorders have a strong connection to genetic predisposition and can be shaped by experience. (Pinel, 2007)
Benzodiazepines and serotonin agonists are the two types of drug classes proven effective in the treatment of anxiety disorders. Benzodiazepines are believed to work as agonists by binding to GABAA receptors increasing the binding of GABA receptors. Benzodiazepines are extremely addictive and only recommended for short-term use; other side effects include: problems with motor activities, nausea, tremors, sedation, and rebound anxiety. Serotonin agonists are often used to treat anxiety disorders, because they do not have the same side effects as benzodiazepines; however, they come with their own side effects: nausea, headaches, insomnia, and dizziness. Serotonin agonists work through the agonist effect on the 5-HT1A serotonin receptor. (Pinel, 2007)
Tourette Syndrome
Tourette syndrome is a disorder that causes involuntary tics in movement or vocalizations typically beginning in childhood. Approximately 200,000 Americans are afflicted with acute Tourette syndrome, and one in 100 live with milder forms of the disorder (National Institute of Neurological Disorders and Stroke, 2008). Tourette syndrome may coexist with Attention Deficit Hyperactivity Disorder (ADHD) or Obsessive Compulsive Disorder (OCD), if not both. Very little is known about the neural basis for Tourette syndrome. Tourette syndrome is successfully treated with neuroleptics that block D2 receptors (those also used to treat schizophrenia). (Pinel, 2007)
Conclusion
Schizophrenia, affective disorders, anxiety disorders, and Tourette syndrome are all complex disorders. Biomedical treatments are often trial and error, until a medication is found that successfully helps the patient manage symptoms. Biopsychology is focused on discovering the causes and developing effective treatments; however, there remains much that psychology and the medical field do not yet know about the causes, symptomology, and best treatment practices.
References
Challoner, K. R. & Newton, E. J. (2008). Toxicity, Neuroleptic agents. Emedicine from WebMD. Retrieved from http://www.emedicine.com/emerg/topic338.htm
National Institute of Neurological Disorders and Stroke. (2008). Tourette syndrome fact sheet. National Institue of Neurological Disorders and Stroke; National Institutes of Health. Retrieved from http://www.ninds.nih.gov/disorders/tourette/detail_tourette.htm
Pinel, J. P. J. (2007). Basics of biopsychology. Boston, MA: Allyn and Bacon.
Comments