Childhood or infantile amnesia refers to a person’s inability to remember specific events from childhood and infancy, typically prior to the age of four. Famed psychoanalyst Sigmund Freud believed childhood amnesia was a response to sexual repression. It has also been hypothesized that memories need to be stored conceptually and associated with words and meanings that people don’t attain until about the age of four. It is also possible that the young child’s brain does not have sufficient development to properly store memories. At birth babies have billions of brain cells, but there are relatively few connections between them.

Infant and childhood stress have been linked to memory decline at an early age. A 2005 study by the UC Irvine School of Medicine suggests that the emotional stress associated with parental loss, abuse or neglect may contribute to the type of memory loss during middle-age years that is normally seen in the elderly. The study involved limiting the nesting material in the cages of neonatal rats, which led to an increase in stress for these rats. In middle age, these same rats began to demonstrate deficiency in their ability to remember the location of objects they had seen before, as well to recognize objects they had seen on the previous day. These memory problems were far more pronounced than rats who had been raised for the first week of life under a typical nurturing environment. In the rats with impaired memory, the normal increase in brain communication through synapses, considered to the basis for memory, was found to be faulty.

(B. Bower "Early stress in rats bites memory later on: inadequate care to young animals delivers delayed hit to the brain". Science News. Oct 22, 2005. FindArticles.com. 06 Nov. 2006).