The Biomedical Model Of Depression

Depression is a mood disorder and the biomedical model portrays one way in which it can be understood. The biomedical model focuses on biological factors alone in an attempt to explain an illness or a disorder. It describes illnesses as disturbances within the human body that can be altered and corrected. Very unlike the biopsychosocial model, it doesn’t include other factors that may contribute to a disorder such as their psychological state or their social context. The biomedical model focuses on activities within the brain alone that can cause disorders like depression. In this assignment I will explain how biological processes in the brain can arguably be perceived to cause depression.
The prefrontal cortex is divided into two hemispheres.
The left hemisphere is believed to be associated with positive emotion, whilst evidence suggests that the right hemisphere is involved in negative emotions. Sobotka et al cited in Toates (2010 p.40) claimed that in an experiment participant who were given rewards showed increased activity in the left hemisphere as opposed to the participants who received punishment where more activity was seen in the right hemisphere.
The Limbic System is an area of the brain that is responsible for the regulation of emotions. It is made up of the hypothalamus, amygdala and hippocampus. The activities of the limbic system are very complex and important. The hypothalamus is responsible for regulation of body temperature, sleep, responding to stress as well as controlling the pituitary gland. The amygdala and hippocampus are considered to play an important role in the reaction to emotion which will be explained futher on.
Neurons can be found in the brain, their role is to transmit messages both within the nervous system and between the nervous system and parts of the body.
There is a tiny gap between two neurons known as the synapse. Neurotransmitters cross the synapse from one neuron to another and attach onto the receptors of the receiving neuron. Neurotransmitters and receptors have a lock and key relationship; therefore, only specific neurotransmitters will fit into a certain receptor. It is suggested that depression can be caused by a chemical imbalance in the brain such as an imbalance of the neurotransmitters serotonin and dopamine. They have been identified as playing a primary role regulating emotions, regulating appetite, ability to sleep and so
on.
Hormones can have different effects throughout the body and can have an impact on the way we behave and our mental state. Levels of certain hormones in particular can have an effect on our mental health. The endocrine system works with the brain to control numerous activities in the body. The endocrine system is made up of glands that both create and release hormones into the blood. High levels of hormones can effect sleep and appetite The hypothalamus in the brain is responsible for controlling the pituitary gland which is responsible for the release of hormones by in the other glands. Therefore, the problems in the endocrine system can be effected by changes that occur in the brain
There is some evidence to suggest that hyperactivity of the hypothalamic-pituitary axis could be involved in the process of depression. The amygdala releases a corticotrophin-releasing factor (CRF) to stimulate a response from the sympathetic nervous system. This CRF signal then travels to the hypothalamus which then releases it as a signal to the pituitary gland. On its arrival to the pituitary gland the adrenocorticotropic hormone is released into the blood. The adrenal glands release corticosteroids otherwise known as glucocorticoids into the blood such as cortisol. Hyperactivity in the HPA can result in glucocorticoids, causing damage to both cells and neurons if present for too long and in high concentration. Hyperactivity is evident in those with depression. High levels of cortisol suggest hyperactivity in the HPA of those who are depressed. Some evidence to suggest that cortisol can cause low mood is the Cushing’s disease, where the adrenal cortex produces more cortisol. A relationship can be seen between reducing levels of cortisol in patients and feelings of depression lifting.
There is also a hypothesis that provides a biological explanation for the role of biology in depression known as the monoamines hypothesis.
Monoamines are group of neurotransmitters serotonin, noradrenaline, dopamine. It is suggested that people that suffer with depression have less of these neurotransmitters available to attach to the relevant receptor of the receiving neuron. Quite similar to that of the biomedical model this hypothesis believes that a solution to this imbalance would be to increase the number of the neurotransmitter in particular in the synapse so that there are more available to be able to attach onto the requiring receptor. This in turn would correct the mood disorder. Low levels of the neurotransmitters serotonin and dopamine are believed to play a key role in causing depression. Hirschfield 2000 cited in Datta (2010 p.59). claimed that low levels of these three monoamines can cause depression whilst increasing these levels will have the opposite effect and lift it . This is supported by Stanley and Mann; Yates et al cited in Datta (2010 p.61) who suggested that the post mortem results of those who were suffering with depression and had committed suicide had a ‘high number of serotonin receptors in the prefrontal
cortex’ Sen et al 2008 cited in Datta (2010 p. 63) suggested that Brain-derived neurotrophic factor (BDNF) levels in the blood of those with depression are lower than in someone who doesn’t have depression. In addition to this patients ( Martinowoch et al cited in Datta (2010 p.64) also claimed that post-mortem results of depressed patients showed lower levels of BDNF in both the hippocampus and pre frontal cortex.
In conclusion, the brain is very complex and there are many processes and activities that occur that could be a cause for depression. Although there is some evidence to suggest that biological processes do cause depression, I think that these processes aren’t always the cause alone, there are other factors that can contribute to the causes of depression.