Biological etiologies

Disorder: MDD intro

Major depressive disorder (MDD) is a mood disorder, it is displayed by affective, Behavioural, Cognitive, and somatic symptoms, according to the which is the DSM-5 it is characterized by the following symptoms: lowered mood most days, reduced interest or pleasure in most activities, significant weight changes, daily insomnia or hypersomnia, reducedor agitated motor activity, fatigue or loss of energy, feelings of worthlessness or inappropriate guilt, diminished concentration and cognition, recurrent thoughts of death, suicidal ideation, and suicidal plan.

The severity of depression ma vary depending on the amount of symptoms experienced, the frequency of symptoms and severity of symptoms, from mild to moderate to severe major depressive disorder.

Why is this a discussion

It is important to discuss the explanations of major depressive disorder (MDD), as it allows for better understanding of the causes of it. The treatment of a disorder like MDD should match its cause, therefore making it important to fully understand the etiologies of MDD to be able to effectively treat it. It is generally thought that the interaction of multiple etiologies is necessary to explain MDD effectively due to the combination of factors and symptoms which are related to it.

Holism

It is generally accepted that depression isn’t caused by solely biological, cognitive or sociocultural factors, but rather a combination of all three. When discussing the etiologies if a mental illness a holistic approach is necessary, and a focus on how the different explanations work together and interact. This can be seen in the widely accepted diathesis stress model of mental illnesses which suggests that individuals have a biological predisposition to a disorder, but it only manifests itself as the disorder when it is triggered by cognitive and sociocultural factors.

Genetic vulnerability/ epigentics

Genetic vulnerability suggest that the genotype creates a predisposition for certain people to a specific condition, such as major depressive disorder, however an environmental factor is necessary for this to be triggered to activation. This is a gene-environment (G x E) interaction which triggers the expression of a characteristic. Epigenetics is the study of how genes are expressed or not expressed in the phenotype. this refers to genes being activated or deactivated through environmental factors. The process of genes being switched on and off is called gene regulation. It is generally acceptable that a gene doesn’t cause a behaviour, however a gene-environment interaction may cause a behaviour to be expressed. For depression environmental factors such as stress, exercise or diet may affect the development of depression.

The 5-HTT (the serotonin transporter gene) gene mutation, is involved in the reuptake of the neurotransmitter serotonin in the brain synapse. The alleles of the mutated gene are shorter than the non mutated alleles. It is suggested that this gene mutation together with environmental factors such as stressful life events can result in depressive symptoms.

Biological etiology: studies

Caspi et al. (2003)

Silberg et al. (1999)

Evaluation: Validity in explaining MDD

+ valid in terms of evidence for certain genes (5-HTT gene) providing vulnerability to disorder.

- not helpful in explaining MDD and its causes as some ppl without genetic vulnerability still develop it and vice versa.

Evaluation: usefulness to individuals who suffer from MDD

+ useful in recognizing MDD isnt personal weakness, just like physical illness some ppl are predisposed to it. can reduce self-blame and guilt

+ useful in reducing stigma, medicalization of mental health, help ppl view MDD as illness rather than personal weakness or individuals not coping w/ life. reduces judgement placed on ppl with MDD

- not useful as can be interpreted as determinism, inevitable that individual develops MDD. can lead to hopelessness and resignation, rather than steps to change life for the better.

- not useful for individuals who arent genetically vulnerable, as this can lead to feelings of personal weakness

- may cause blame within families due to inheritance of a genetic predisposition.

Evaluation: usefulness in terms of treatment

+ knowing of a predisposition can allow for identifying and managing environmental factors which may trigger expression of MDD

- it isn’t possible to alter genetic predisposition

- reductionist as it doesn’t consider psychological factors (thought patterns), or hormonal factors

- doesnt help treat MDD in individuals without a genetic predisposition