LONDON (Thomson Reuters Foundation) - Nearly 87 million children around the world under seven years of age have been growing up in conflict zones, in conditions that can hinder the development of their brains, the United Nations Children's Fund (UNICEF) said on Thursday.

Exposure to extreme trauma may hinder the development of brain cell connections, essential for health, emotional wellbeing and ability to learn, UNICEF said.

"In addition to the immediate physical threats that children in crises face, they are also at risk of deep-rooted emotional scars," Pia Britto, UNICEF chief of early child development, said in a statement.

"Conflict robs children of their safety, family and friends, play and routine.

"Yet these are all elements of childhood that give children the best possible chance of developing fully and learning effectively, enabling them to contribute to their economies and societies, and building strong and safe communities when they reach adulthood."

A child is born with 253 million functioning brain cells called neurons, which have the potential to develop rapidly during the first seven years of life before reaching full adult capacity of around one billion neurons, UNICEF said.

This, however, largely depends on early childhood development such as breastfeeding, learning opportunities and a chance to grow up in a safe environment, it said.

Extreme trauma puts children at risk of living in a state of toxic stress inhibiting brain cell connections, with lifelong consequences to their cognitive, social and physical development, UNICEF said.

(Story corrects headline and text to note the 87 million refers to children under 7 years of age.)

(Reporting by Magdalena Mis, editing by Tim Pearce. Please credit Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women’s rights, corruption and climate change. Visit news.trust.org)