Science Daily peers deep into our brains to reveal how exactly our parents messed us all up:
The study is being published this week in the Proceedings of the National Academy of Sciences (PNAS). It shows that elevated activity in this prefrontal- limbic -midbrain circuit is likely involved in mediating the in-born risk for extreme anxiety, anxious temperament that can be observed in early childhood.
“Over-activity of these three brain regions are inherited brain alterations that are directly linked to the later life risk to develop anxiety and depression,” says senior author Dr. Ned Kalin, chair of psychiatry at the UW School of Medicine and Public Health.
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Monkeys, like humans, can be temperamentally anxious and pass their anxiety-related genes on to the next generation.
By studying nearly 600 young rhesus monkeys from a large multi-generational family, Drs. Andrew Fox, Kalin, and colleagues found that about 35 percent of variation in anxiety-like tendencies is explained by family history.
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By closely examining how individual differences in brain function and anxiety-related behavior fall through the family tree, the authors identified brain systems responsible for the parent-to-child transmission of anxiety-related behavior. Using this “genetic correlation” approach, the authors found the neural circuit where metabolism and an early-life anxious temperament are likely to share the same genetic basis.
Interestingly, the brain circuit that was genetically correlated with individual differences in early-life anxiety involved three survival-related brain regions. These regions were located in the brain stem, the most primitive part of the brain; the amygdala, the limbic brain fear center; and the prefrontal cortex, which is responsible for higher-level reasoning and is fully developed only in humans and their primate cousins.
“Basically, we think that to a certain extent, anxiety can provide an evolutionary advantage because it helps an individual recognize and avoid danger, but when the circuits are over-active, it becomes a problem and can result in anxiety and depressive disorders,” Kalin explains.
Surprisingly, these studies found that it was the function of these brain structures — and not their size — that was responsible for the genetic transfer of an anxious temperament.
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Why “the Larkin Effect”? Because Philip Larkin summed it up best.