Early life stress, literacy and dyslexia: an evolutionary perspective

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Stress and learning are evolutionarily intertwined, with the central autonomic network (CAN) regulating moderate stress vital for biological adaptability and cognitive development.
• Reading is a uniquely human achievement, not genetically pre-wired, relying on the co-option of a visual processing brain circuit.

Purpose of the Study:

• To explore the role of the central autonomic network (CAN) in the neurobiological underpinnings of learning to read.
• To investigate how evolutionary adaptations to early-life stress impact reading acquisition and school performance.

Main Methods:

• This review synthesizes existing research on the CAN, stress, learning, and reading development.
• It examines genetic and molecular mechanisms, including gene methylation and BDNF trafficking, in response to early-life stress.

Main Results:

• The CAN coordinates emotional and learning requirements for reading, stabilizing self-control and attention.
• Evolutionary adaptations to early-life stress, while conferring long-term benefits like protection against glucocorticoid toxicity, can lead to dyslexia and school under-performance.
• Specific genetic adaptations (e.g., FKBP5, NR3C1 methylation) are linked to short-term liabilities in academic achievement.

Conclusions:

• The CAN is pivotal for school readiness and learning to read by modulating neural circuits.
• While adaptive, certain stress-induced genetic and molecular changes can disrupt reading circuitry, increasing the risk for dyslexia.