Can Environmental Influences Effect Brain Development in Infants & Toddlers?

Although the brain continues to develop throughout the lifespan, according to Princeton University, the early years of a child’s life are crucial. An infant or toddler has a time-limited period during which her experiences will affect her brain function and development. Nutrition, talking, singing, playing and protection from stress or the dangers of toxins and drugs are important requirements for healthy brain development in infants and toddlers.

Brain Structures

Two brain structures have a significant effect on brain development -- the neurons, or nerve cells, and the synapses, which are connections between nerve cells. A healthy child is born with billions of neurons, and as she has sensory experiences, the brain forms synapses between neurons. Far more synapses are formed than her brain will need, so at the same time the synapses are forming, those that are not being used are gradually eliminated. If this “pruning” did not occur, the university says the brain would have so many synaptic connections that it would be inefficient.


Synaptic changes are related to stimulation. If an infant is deprived of sight in the first six months of life, as sometimes happens with congenital cataracts, the neural pathways that affect sight will develop improperly, according to Princeton University. Even if sight can be restored, the neural pathways will still never function as they should, because they were not used frequently enough to develop properly. The same is true of other sensory pathways. Children learn to speak through constant repetition of words; if they are not spoken to, their language skills may be permanently impaired.

Drugs, Toxins and Disease

A number of substances and diseases can affect pre- and post-natal brain development 1. Among these are drugs such as heroin, alcohol and cocaine. PubMed Health says exposure to alcohol while in the womb can cause fetal alcohol syndrome, which may result in delayed development in thinking, speech, movement or social skills, as well as physical defects. Viruses such as HIV and rubella and environmental toxins such as mercury or lead may also have a negative effect on brain development.

Abuse, Neglect and Stress

Negative experiences can also affect brain development. Abuse, neglect and chronic stress can also cause synaptic development, but the child who results may be violent and overly aggressive, according to the University of Missouri 1. Exposure to violence during the formative years teaches children to expect danger rather than security. These children may have problems with self-control later in life. For example, adult depression interferes with early brain development 1. When adults caring for the infant are depressed, they may be emotionally unavailable or be unresponsive to the infant.