I am quite fascinated by generalized control mechanisms and the role they play in the nervous system. I am also quite curious about the relationship between different generalized control mechanisms. The concept of mood and depression in particular have always interested me. I have always wondered what actually causes depression. Why can some people be in a perfectly good mood one day and then less than a week later start exhibiting the signs of clinical depression? I have always been curious about the role that experience and chemical imbalances play in depression and other mood disorders. I donUt totally understand how chemical depression can originate as the result of severe outside stressors in a personUs life. How can this stress go from simply stress in the experiences and environment of a person to a chemical imbalance? I have also wondered why certain people are more susceptible to depression than others. I am curious about whether genetics play a role in depression and whether certain people are more susceptible to depression because of the environment they live in or because of pharmacological reasons and genes. Throughout our class this year, I have wondered about the role that the I-function plays in depression. I find it interesting that it is possible to wake up one morning and be in a nasty mood even if I want to be in a good mood and my I-function is thinking RhappyS thoughts. Through my research for this paper I wanted to find out more about the different kinds of depression and exactly what goes on chemically in the brain when a person is depressed. I also wanted to do a little research on how depression can be treated. I wanted to try and determine how and when the line of simply outside influences and environmental stressors is crossed to cause chemical imbalances in a person. Through my research I wanted to learn about exactly what anti-depressants do chemically . I also wanted to determine what role genetics, heredity, environment, and biological factors play in depression. Though I was not able to answer all of these questions, I learned a lot about depression and even developed some theories of my own. For a long time, I have thought of some forms of depression as a weakness. I truly believed that in many cases it could be controlled by the depressed person themself. I also felt that environmental and personal factors played were the basis for depression. However, through what we have learned in class and from my research, I have come to realize that this theory is not completely true. Mood is a generalized control mechanism like sleep. Eating also exhibits many characteristics of generalized control mechanisms. Mood can be affected by sensory input and the I-function, but it is also autonomous in that it can vary independent of sensory input. This internal variation is pharmacologically dependent. Changes in a persons pharmacological makeup can cause mood changes, sleep disturbances, and even depression. The I-function influences mood manipulation but cannot determine mood. Though you may want to be in a good mood, make a conscious effort to think RhappyS thoughts, and may not have serious stressors in your life, you may still suffer clinical depression as a result of a chemical imbalance in your system. Depression can be physical and chemical and can be caused by things totally unrelated to the I-function and personal thoughts and experiences.
I was shocked to learn that approximately 10% of the population is depressed at any given point in time and that 20% of the world population will experience a bout of depression at some point in their lives. Clinical depression is characterized by a list of symptoms that last over a long period of time. It is a serious problem that is usually, initially caused by outside stressors. These stresses escalate and eventually result in a chemical imbalance. Clinical depression can be very dangerous and can even lead to death that the depressed person may bring about by their doing. Some typical signs or symptoms of depression are as follows:
* Impaired concentration
* Inability to experience pleasure
* Increase in self-critical thoughts with a voice in the back of one Us mind providing a
constant barrage of harsh, negative statements
* Sleep disturbances or inability to fall back to sleep
* Feeling fatigued after a significant amount of sleep
* Decrease in appetite or food loses its taste
* Feelings of guilt, helplessness and/or hopelessness
* Thoughts of suicide
* Increased isolation
* Missing deadlines or a drop in standards
* Change in personality
* Increased sexual promiscuity
* Feeling of loss of self
* Increase in alcohol and drug abuse
(these symptoms were obtained from sources 1, 2, 3 and 4)
By analyzing many of the symptoms of depression, I was able to make more sense of them and was able to relate them to other generalized control mechanisms. This analysis also helped me to see the aspects of both sensory input and chemical imbalance in depression. Knowing that sleep is also a generalized control mechanism and that appetite and eating exhibit many of the characteristics of generalized control mechanisms, I theorized that the sleep disturbances and loss in appetite have a lot to do with chemical imbalances. I read an article that said that studies have actually found correlations between circadian rhythm disturbance and Bi-polar Disorder, which is one form of depression.(5) The feelings of guilt and increase in self-critical thoughts seem to be related to and affected by the I-functionUs influence. I theorize that the changes in personality are affected by both chemicals and the I-function. I came to this theory through my knowledge about personality. We learned in class that aspects of a person that characterize personality do not require the I-function to be present and aware. People that sleep walk often exhibit aspects of their personality even though they(their I-functions) are not even aware that they(physically) are awake. However, personality can be affected by the I-function and the I-function definitely plays a role in a personUs sense of self which includes the I-function. Using my own assertion as well as those made in class that the I-function plays and important role in a personUs sense of self has led me to theorize that personUs feeling of loss of self during depression is be related to the I-function. The increased drug and alcohol abuse is probably related to the chemical imbalance in a depressed person, for it has been suggested many times that depressed people may use alcohol and drugs to self-medicate themselves and relieve the feelings caused by a chemical imbalance in the brain. There are many different types of depression. These include: Major Depressive Disorder, Dsythymia, Bi-polar Disorder, Post-partum Depression, and Seasonal Affective Disorder(SAD). These forms of depression are different in symptoms and causes but all are caused by some sort of chemical imbalance.
Major Depressive Disorder is one of the most serious forms of depression. It is characterized by a significant amount of the above mentioned symptoms and when untreated, it can last from nine months to a year. This form of depression seriously disrupts and interferes with a personUs ability to work, sleep, and enjoy the everyday pleasures of life.(1)
Dysthmia is a less severe form of depression also characterized by the previously mentioned symptoms. It is long term and its symptoms are chronic. This form of depression is not disabling but inhibiting and causes bouts of major depressive moods.(1) Bi-polar Disorder is the form of depression that was formally known as manic depression. Bi-polar Disorder is characterized by alternating cycles of depression and elation. During the depressive cycles, a person with Bi-polar Disorder exhibits the symptoms of depression previously mentioned and during the elation or mania cycles, manic characteristics are exhibited. These include: inappropriate elation and mania, irritability, insomnia, increased sex drive, grandiose notions, racing thoughts, poor judgment, and inappropriate social behavior. The manic cycles can seriously affect thinking, judgment, and social behavior. The alteration of the cycles of depression and mania are always quite dramatic and can be either gradual or rapid.(1) Post-partum Depression is depression that many women experience after having a baby. It can be quite severe and it is the result of serious hormonal imbalances in a women after childbirth.(1) Seasonal Affective Disorder(SAD) is a seasonal form of depression that is affected by the coming and going of different seasons. It is often accompanied by a decrease in energy, an increased need for sleep and carbohydrate craving. Phototherapy for SAD has been proven to be quite helpful. Phototherapy is a form of therapy in which a patient is receives morning exposure to bright, full spectrum light.(1) People are susceptible to depression for many reasons. Depression seems to be caused by a combination of environmental as well as chemical factors.(6) Depression has been proven to be affected by factors of the environment and personal experience. This evidence suggests that people surrounded by serious stress may be more susceptible to depression than people with less stress in their lives. Separation and the loss of a loved one seem to be serious stressors that often lead to depression. The fact that separation and loss of a loved one can be a serious cause of stress makes me wonder about peopleUs necessity for other people and their necessity for love, companionship, and affection. I know their have been many studies on people that have shown correlations between the amount of love and affection people receive and their development and ability to function. The fact that separation can lead to depression seems to be just another piece of evidence to support the on-going theory that love, affection, and human companionship play an important role in normal development and functioning in humans. Women seem to be more often affected by depression than men.(2) Though I found no evidence on why this is, I have developed my own theories about it. I believe that the higher rate of depression in women than in men is partially due to environmental factors such as societal pressures on them as well chemical and hormonal imbalances that are the result of childbirth and menstrual cycles. Depression has also been proven to run in families and therefore may be genetic.(6)
Depression is believed to originated in stress which eventually results in chemical imbalances that upset communication in the brain and lead to stress. I am extremely curious about how this chemical imbalance results from stress. Though I was unable to find any clear-cut evidence that would explain this phenomena, I have developed my own theories about it. I feel that serious stress may cause an over-exertion of neurotransmitters. As people attempt to deal with stress they may eat, cry, physically exert themselves, or perform other activities to relieve the stress. People also tend to think whether rationally or irrationally during depression. All of these activities require a lot of communication in the nervous system, specifically in the brain. As neurotransmitters work double time to perform activities they may not be used to performing, they become exhausted. There are hormones that play an important role in these activities that may also over-exert themselves and people that are stressed are often more susceptible to infection, and other medical problems which cause their immune systems to work double time. The action of these systems over-exerting themselves, may result in chemical and hormonal imbalances. These imbalances disrupt the communication necessarily for normal functioning of the nervous system. This eventually lead to clinical depression.
It is believed that serotonin and norepinephrine are the neurotransmitters that are affected during depression. Through many studies, it has been determined that most patients suffering from depression exhibit a severe decrease in both serotonin and norepinephrine. Serotonin (5-hydroxytrytamine, 5-HT) is a neurotransmitter that is simple in structure, but quite complex in its chemical abilities. The function of all neurotransmitters is determined by their interaction with receptors. The functions that serotonin serve involve: control of sleep, memory, learning, temperature regulation, mood, behavior(sexual and hallucinogenic), cardiovascular function, muscle contraction, endocrine regulation, and depression. It is made in brain neurons and stored in vesicles. During nerve impulses, serotonin is released into the synaptic cleft and then interacts with postsynaptic receptors. This interaction determines the function of the serotonin. The actions of serotonin are terminated by diffusion, metabolism, and uptake back into the synaptic cleft. The receptors have been split up into different categories based on their functions. The 5-HT1 receptors have been determined to play the most important and obvious role in depression . These receptors have been determined to play a significant role in smooth muscle relaxation, contraction of cardiac and vascular smooth muscle, rejuntial inhibition of neurotransmitter release and other affects in the CNS. The inhibition of neurotransmitter release is probably what is disrupted and plays an important role in depression. 5-HT1A receptors are located in the CNS and believe to play an extremely important role in depression.(7 and 8) It is speculated that the decreased levels of serotonin, norepinephrine, and hormonal abnormalities cause problems with communication in the brain and cause the symptoms characteristic of depression.
Luckily, depression can be treated. There are many forms of treatment for depression. These include therapy in which the patient communicates with a therapist, antidepressants, and Electroconvulsive Therapy. These forms of treatment are a combination of pharmacologically related treatment as well as I-function and personal experience related treatment. A combination of these forms is usually necessary to overcome depression, because of the fact that depression is usually the result of a combination of environmental and personal experience factors as well as a chemical imbalance.
Two forms of therapy that are most effective in patients with depression are cognitive behavior therapy and inner-personal therapy. Cognitive behavior therapy deals with motivational thinking and revising the everyday behaviors of the patient suffering from depression. Inner-personal therapy deals improving the personal relationships that the person suffering has with the people around them. Both of these forms of treatment have been proven to be quite helpful and effective. There is quite a range of antidepressants that are used to relieve the symptoms of depression. These include, drugs that mimic the activities of norepinephrine(NE), monoamine oxidase Inhibitors(MAOIs) which inhibit the metabolism of norepinephrine and serotonin, the tricyclic antidepressant(TCAs) drugs that increase levels of norepinephrine and serotonin at the receptors by inhibiting the uptake of NE and 5-HT and serotonin re-uptake inhibitors(SSRIs) drugs that inhibit specifically the uptake of 5-HT, and drugs that inhibit uptake of norepinephrine, serotonin, and dopamine. The drugs that inhibit the metabolism and uptake of serotonin, norepinephrine, and dopamine are believed to work by increasing levels of these neurotransmitters at the receptors.
Clomipramine(Anafranil), a SSRI was the first medication used for obsessive-compulsive disorder. The tricyclic antidepressants include amitriptyline(Elavil) and desipramine(Norpramin). The most common side affects of these are dry mouth, drowsiness, weight gain, constipation, sweating, increased pulse, and reduced blood pressure. Phenelzine(Nardil) is a commonly used monoamine oxidase inhibitor. The most common side effects of this drug are dry mouth, insomnia, increased heart rate, lowered blood pressure sedation, and over stimulation. Fluoxetine(Prozac), sertraline(Zoloft) and paroxetine(Paxil) and the newest and most common antidepressants. They are most commonly used because they cause less severe side effects than the other antidepressants. The most common side effects of these drugs are decreased sexual interest and other sexual problems, nausea, sedation, dizziness, headache, nervousness, insomnia, diarrhea, and dry mouth. Venlafaxine(Effexor) inhibits the uptake of norepinephrine, serotonin, and dopamine. Its most common side effect are nausea, headache, sleepiness, dry mouth, insomnia, and constipation. Although many of the above mentioned drugs are quite effective in relieving the symptoms of depression, in people suffering from Bi-polar Disorder, these drugs cause a constant state of mania and elation. Bupropion(Wellbutrin) is used in many patients with Bi-Polar Disorder to reduce the possibility of these constant states of mania. This most common side effects of this drugs are agitation, weight loss, dizziness, and a decreased appetite.(9, 10, 11 and 12)
When used together, therapy and antidepressants can be quite affective in relieving depression. However, many patients do not like the idea of using drugs or try drugs and the side effects are too severe for them or the drugs simply do not work. Electroconvulsive Therapy (ECT) is an option for these patients. In ECT, an electrical stimulus is administered through electrodes to the head of the patient. This electrical stimulus produces a brain wave(EEG) change that is quite similar to a grand mal seizure. This process, when repeatedly practice on many victims of depression often relieves that stress and symptoms of depression.
Through my extensive research on depression I have learned a lot of new things. I have learned about the many forms of depression and treatment for depression. I have also learned a little about what is believed to go on chemically in the brain of a clinically depressed person. I was also able to partially determine what sort of role genetics, chemicals and personal influences in the brain. Though I was unable to determine exactly how environmental and personal stress can cause a chemical imbalance in a person, I was even able to speculate about this issue and determine some theories of my own on why and how this may happen.
(1) Depression FAQ.
This page answers many of the most frequently asked questions about depression.
(2) The Deep Dark Tunnel of Depression.
This page offers a lot of background information about depression.
(3) A Guide to Understanding Depression vs. Sadness.
(4) The Harvard Mahoney News Science Institute Letter: On the Brain, Depression.
This page has questions about depression answered by professional doctors.
(5) Circadian Rhythms Factor in Rapid-Cycling Bipolar Disorder.
This page shows correlations between circadian rhythm disruption and Bi-polar Disorder.
(6) Ask the Expert-Depression: Genes or Environment.
(7) A Serotonin Re-uptake Inhibitor Used for Treatment of Major Depressive Disorder.
(8) Serotonin: The Neurotransmitter of the 90s.
(9) Depression is a Treatable Illness.
(10) The Essential Guide to Prescription Drugs.
(12) Antidepressants FAQ.
(13) Major Depressive Disorder: American Description.
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This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.