Is Clinical Depression Hereditary?
It is unknown exactly what causes clinical depression, which is also called major depression or unipolar depression. But it does run in families, which suggests there may be a genetic cause which makes a person more liable to get depression than someone else. The National Alliance on Mental Illness (NAMI) suggests that it takes more than just genetics for depression symptoms to be triggered.-
Gene
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The gene thought to be responsible for making someone have depressive tendencies is called short allele 5-HTT. According to the UK's National Health Service (NHS), this gene can be directly inherited in children from their parents. But having this version of 5-HTT does not mean that a person will always get depression. It just means that they are more likely to get depression than those with the full version (allele) of 5-HTT.
Significance
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People with the full allele 5-HTT are thought to be able to process neurotransmitters better. Neurotransmitters are chemicals in the brain that helps the brains neuron cells communicate with each other. They can affect mood, appetite and sleep cycles. People with the short allele 5-HTT are thought to have not enough of some types of neurotransmitters and too much of other types.
Size
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The NHS estimates that 20% of the world's human population has the short allele 5-HTT. According to CVS Health Resources, depression passes to children an estimated 75% of the time if both parents are clinically depressed. The odds drop to 25 - 50% if only one parent is clinically depressed.
Speculation
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It is unknown how much the parenting style and actions of clinically depressed parents influence whether children who have inherited the short allele 5-HHT gene develop depression. It is also unknown how much stressful life events play in depression. It could be a combination of all three things--having the short allele 5-HTT gene, being raised by depressed parents and encountering stressful events can trigger full-blown clinical depression.
Other Risk Factors
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A person already at risk of getting major depression through their genes may not develop any symptoms until they encounter other risk factors such as alcohol or drug abuse, surviving a natural disaster or other traumatic event, the death of a loved one, development of a chronic health condition like migraines or being poor.
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