A number of factors influence brain development, both in utero and over the course of a lifetime, because the brain is never fully developed. In fact, this unique organ is constantly growing and changing in response to experience, and at any given time, things can both enhance and hinder brain development.
In utero, the brain starts to develop very early. The mother's diet can have a profound impact on brain development, especially after 20 weeks. Infections in the mother also appear to have a role in how the fetal brain grows, as does the use of many drugs, ranging from prescriptions to illegal drugs such as cocaine to compounds found in alcohol and cigarettes. Pregnant women have to be very careful about what they ingest because most things work their way to the fetus, and many things can interfere with the growing brain.
After birth, the first three years of life are a critical phase in development of the brain, because the brain is growing and changing rapidly to accommodate the sudden rush of stimuli experienced by the child. Research has suggested that nutrition continues to play a role in brain development, as does exposure to harmful chemicals. Furthermore, enrichment of the baby's life is very important.
Children who have experienced gentle, loving care and the establishment of firm connections with other people from a very young age appear to experience more even and full development of the brain. Likewise, children who are exposed to rich and varied stimuli including music, art, speech, and so forth tend to have better brain development over time. Neglect, abuse, and lack of exposure to a variety of experiences can actually harm a developing brain.
Studies have also found that there are several critical periods, during which the brain establishes pathways for specific function. At around two months, for example, babies experience a critical period in the development of their vision. If children are not exposed to lots of visual stimuli during this period, or a minor eye condition goes undiagnosed, they can experience lifelong vision problems because their development during this critical period was incomplete.
There are a number of products which are supposed to make “smarter babies” by targeting specific areas of brain development. However, studies have shown that these products don't have as much of an impact as real-life connections with people. For example, a parent reading a story to a child appears to be more beneficial than a parent drilling a child with alphabet flash cards, or a parent playing a recording of someone reading a story. Even talking to and playing with an infant can be beneficial, with no special tools or experience required.
Adult brains can also be influenced by factors such as diet, exposure to certain chemical compounds, and stimuli. Someone who routinely uses illicit substances, for example, may experience impaired brain development as a result of interactions between these substances and the brain. Tobacco, caffeine, and many other commonly used chemical compounds also impact the way in which adult brains grow and respond to changes in their environment.