Unipolar depression or also known as Major Depressive Disorder (MDD) is mood disorder that is characterized by a consistent low mood over two weeks or more, feelings of hopelessness and lack of interest in daily activity, this disorder can cause the individual to have severe long – lasting psychological pain which progresses over time. Psychologists claim that 5 areas of functioning are affected within this disorder; ‘motivational’ (lack of drive), ‘behavioural’ (become less productive/spend a lot of time in bed), ‘physical’ (headaches and changes to sleep and appetite patterns), ‘emotional’ (feeling low, miserable and empty), and ‘cognitive’ (negative views on themselves and are pessimistic). According to the World Health Organisation 2008, Unipolar depression is very prevalent and the second leading cause of disability worldwide, Gonzalez, 2011 found that the possibility of facing this has increased since 1915 and statistics uncovered by Kessler, 2005 found in the US 17% of adults will suffer from unipolar depression at some point in their lives and 7% of adults suffer from severe depression yearly, this prevalence is seen to be alike in several countries.
The first theory I will be discussing is the Biological view, researchers of this topic believe that depression is caused by a genetic predisposition that is inherited. Research on 200 twin studies by McGuffin, 1996 discovered that if one person from an identical twin had depression there was a 46% chance that the other one would to, however in non – identical twins there was only a 20% chance. In pedigree studies those who were diagnosed with MDD were found to have a 20% chance that someone in their family would have it to, as opposed those without the disorder where there was a 10% chance. Brain autonomy/circuits is another factor that researchers look at, they imply that emotional reactions are linked to brain circuits and this network of structures work together to create emotional reactions in the brain. Circuits for disorders such as Panic disorder and OCD have been found so they assume there would be one for depression as well, however, they haven’t been able to map a clear circuit for depression which could be a limitation to this area. Additionally, researchers also look at biochemical factors as being a cause of depression, they focus on two neurotransmitters; norepinephrine and serotonin, in the 1950’s scientists developed medication for high blood pressure but later found that the medication was actually decreasing levels of serotonin and norepinephrine which was found to cause depression, these findings were useful and significant within this area as they were able to develop anti – depressants from prior knowledge, such medication increased the levels of both neurotransmitters in the brain which in turn reduced the symptoms of depression. However, a limitation is that depression isn’t caused by just these two neurotransmitters but an interaction of them both alongside other neurotransmitters could be a possibility.
A strength to the Biological view is that its findings have helped to develop anti – depressants and other treatments for those with depression, whilst also providing some scientific explanations into the development of MDD. However, some limitations of this approach are that is doesn’t take into consideration other factors that could trigger depression, for example environmental factors or stressful life events, which can be explained by the stress diatheses model. The use of twin studies isn’t always good as it is difficult to generalize such data to wider population, furthermore, it is hard to separate the effects of the environment and effects of genes on individuals to determine specific factors.
The second theory I will be talking about in relation to depression is the Psychodynamic view by Freud and Abrahams, they found that there was a link between grief and depression, when their patients came in to speak to them about their problems they would express symptoms of grief that were found to be very similar to those patients that came in for depression, therefore linking them together. In Freud and Abrahams interpretation they believed that the loss of something like a job or more specially a loved one causes an unconsciousness process to start, the individual represses to the ‘oral stage’ and begins to feel what they call ‘introjection’, for a lot of people this part is only temporary and they get better, but for some it progresses overtime and gets worse, if such feelings last a long time and are severe it can lead to MDD. Going back to Freud’s initial stages, he claimed that those who have ‘oral stage’ problems (childhood issues such as low self -esteem) are more likely to develop depression. They also propose that not everyone goes on to experience losing a loved one, some people experience what they call ‘symbolic loss’ which is when an event occurs in an individual’s life that causes them to feel the same kind of loss , an example of this would be someone losing several competitions and feeling like they have let everyone down and lost the love from them leading to feelings of sadness.
Some support to this view comes from research on ‘anaclitic depression’ and ‘early loss’ this is where infants were separated from their mothers and began to show some symptoms of depression such as disturbances to sleeping/eating patterns alongside being ‘withdrawn. This theory has also had a big impact in its field and has influenced theorists such as Beck (1983) to develop models. A limitation to this theory is that it is hard to test scientifically, this is because many of its characteristics cannot be operationalized to be tested empirically according to Mendelson 1990, furthermore, early loses in childhood might not necessarily be the only cause for MDD as other factors could affect it.
There are several models (psychological/biological) that try to explain how MDD develops in individuals, they have all contributed good ideas into this field, however there isn’t on prominent explanation overall, they all contribute differently.