Mother’s Stress, Anxiety Impact Fetal Brain Development

Newly published research that uses MRI scans to show how overproduction of stress chemicals in a pregnant mother can affect the developing brain of the fetus underscores more than 30 years of observations, studies and clinical experience at the Mind-Eye Institute in Northbrook, Illinois.

“These scientific findings provide additional evidence that chronic stress and anxiety during pregnancy can slow the maturation of the newborn’s visual processing capabilities,” says optometrist Deborah Zelinsky, OD, founder and executive director of research at the Mind-Eye Institute. She and her team have been working to develop visual processing skills in babies, toddlers, and children who are labelled as “developmentally delayed” or “learning-disabled” or are diagnosed as having dyslexia, attention deficit hyperactivity disorder (ADHD) or some form of autism.

The term “visual processing” refers to the brain’s almost instantaneous ability, consciously and subconsciously, to take in external sensory signals (from eyesight, hearing, smell, taste, and touch), combine them with a person’s internal sensory signals, and then process the information, allowing a person to react and respond normally to his or her environment.

“Visual processing skills are essential to all aspects of learning, but the precursor factors are often disrupted when the fetus is exposed to high levels of environmental stressors,” Dr. Zelinsky says. Stressors hypersensitize the newborn’s peripheral eyesight (designed to be aware of threats), putting it in fight-or-flight mode. Stressors also can prevent the natural integration of a newborn’s primitive reactions, such as the Moro (protective) reflex. When the primitive reflexes fail to all integrate, then development of postural reflexes, those that subconsciously govern a child’s posture, body alignment, head control, and eye-hand coordination, is often hindered.

The latest study, appearing in the journal eLife, was led by University of Edinburgh scientists. Through brain imaging, they determined that high levels of the natural stress chemical cortisol found in hair samples of study participants were associated with changes in specific structures within the brains of their offspring – most notably, the brain’s amygdalae glands. The amygdalae play a major role in a person’s fight-or-flight reactions, fear circuitry, memory, behavior, social skills, sensory processing, and emotional learning and regulation.

“As an infant reaches several months of age, the relationship between eye movement synchronization and posture mechanisms starts to become more solidified. The child learns to sit and hold up its head. Righting of the head when the body is tilted is usually associated with normal visual development,” Dr. Zelinsky says.

“B studies, like the one conducted by the University of Edinburgh, increasingly demonstrate when there is an overproduction of stress chemicals, some cross the placental barrier and affect the fetus. The result is often a slowing or inhibition of the infant’s reflex-maturation process after birth.”

A child may show signs of vestibular, visual, and auditory hypersensitivity when protective mechanisms, such as the startle reflex, persist for too long a period – beyond four or five months. Vestibular hypersensitivity may affect a child’s balance and eye-hand coordination. Visual-perceptual and eye-ear disorders are manifested in abnormal eye movements, light, and sound sensitivities, and slowed or hypersensitive peripheral eyesight reactions to moving objects, Dr. Zelinsky explains.

The Mind-Eye team is able to test these reflexes in babies as early as four months of age. “All of these factors can – and do – impact a child’s later ability to learn and to interact normally with others,” she says.

The Institute is using therapeutic eyeglasses and other advanced mind-eye optometric techniques to address symptoms of brain injury and neurological disorders and help develop – or re-establish – patients’ visual processing capabilities. “Brain” glasses bend light in different ways across the retina, which is composed of brain tissue and is part of the central nervous system.

Light is the way in which the retina communicates with the brain, and the brain reacts and responds. The light is first converted into chemical signals, which, in turn, trigger electrical signals that propagate through nerves. New research shows that these nerve signals affect blood flow (neurovascular coupling of nerves and blood vessels is important). In fact, the eye plays a critical role in routing information through multiple pathways to the brain’s grey matter. Variance in light signals can create new brain signaling pathways that are uncorrupted by injury or disease or they can rebuild (or, more often, circumvent) damaged ones. The goal is to enhance a patient’s spatial awareness and perception, Dr. Zelinsky says.

She concurs with neuroscience and behavioral researchers who say that continued studies of the link between stress in pregnancy and learning and emotional development in children can lead to more effective strategies for supporting the mental health of pregnant women and promoting healthy development of fetal brains.

“As optometrists, we are in position to be at the forefront of developing or re-establishing normal brain function by using eyeglasses to alter patients’ nervous systems. We are in an era of new science, which is providing us much more knowledge about the interconnections between mind and body. This information is enabling optometrists and other professionals to evaluate and address symptoms related to brain injury, learning difficulties, and other neurological disorders,” Dr. Zelinsky says. Some of the neuroscience research has not yet found its way into the ophthalmologic or optometric journals.

“’Brain’ glasses are not about achieving 20/20 clarity. They are designed to improve patient comfort by rewiring dysfunctions in peripheral retinal signals. The intent is to resynchronize brain circuitry with motor and sensory systems in order to improve a patient’s overall visual processing,” Dr. Zelinsky says. “Lessening a pregnant woman’s visual stress can help the overall tolerance level. The unborn baby experiences stress in two ways – from the inside of the womb due to the mother’s stress and from the outside by sudden unexpected movements, such as when the mother is struck.”