Our body cells continually divide and replicate themselves. When they do so the DNA contained in them passes on instructions as to what the new cells need to do. DNA is stored in pairs of strands called chromosomes. There are 'buffers' at the end of each chromosome to protect the DNA. These buffers are called telomeres. Each time one of our body cells replicates, the end-most part of chromosome will not be replicated. Once this buffering telomere is gone and DNA is exposed, the cell stops replicating, ages and dies. That’s the current theory around aging.
Telomere shortening begins in childhood and is accelerated by a range of things, including oxidative stress (another story altogether - but that's something that may be slowed by eating foods that slow this process, such as fruit and vegetables). Telomere shortening can also be accelerated by autoimmune disease, obesity, diabetes, and cardiovascular disease, so if you can control all those and eat vegetables, you're on a winning ticket.
A recent research study has suggested that childhood adversity, anxiety, and depression probably also accelerate telomere shortening. The mechanism whereby this occurs may also lead to increased oxidative stress. This study was published in the journal Biological Psychiatry by Tyrka and colleagues (2014), who recruited four groups of people:
1. Healthy controls (no adversity and no psychiatric disorder);
2. Those with a history of childhood adversity (such as parental death, socioeconomic adversity, serious maltreatment, or desertion by a parent) but no psychiatric disorder;
3. Those with a lifetime history of anxiety or depression, or past history of substance abuse (but not current substance abuse) and without a history of childhood adversity;
4. A group with both adversity and lifetime anxiety, depression and/or substance abuse.
All participants were free of acute or chronic medical conditions and were not taking mental health medication so that these factors shouldn't influence the results.
Results showed that the normal controls had the longest telomeres (which would protect the DNA more), the group who had experienced adversity but had no psychiatric disorder was intermediate, and the two groups that had a lifetime psychiatric disorder of anxiety or depression or past substance use had the most shortening (and were fairly similar whether they had experienced adversity or not).
This could be interpreted to mean that depression, anxiety and substance abuse over a lifetime might be even more 'toxic' in its effects on DNA replication than childhood adversity. This is not conclusive, as these findings need to be replicated in further studies.
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