Multiple moves during childhood can increase the risks of depression in later life

The research, published in the journal JAMA Psychiatry, analysed all residential locations of almost 1.1 million people born in Denmark between 1981 and 2001 and who stayed in the country during the first 15 years of their lives.

It then tracked those same individuals into adulthood, and found at least 35,000 of those still living within Denmark had subsequently received a medical diagnosis of depression.

As part of a detailed analysis, the study supported existing evidence by showing that individuals who live in income deprived neighbourhoods during childhood are more likely -- by a factor of around 10% -- to develop depression in adulthood.

However, it for the first time showed that experiences of moving during childhood -- whether between or within deprived or non-deprived neighbourhoods -- is also associated with significantly higher rates of depression in adulthood.

Specifically, children who move once between ages 10 to 15 are 41% more likely to be diagnosed with depression than those who don't move. And if a child moves twice or more between the ages of 10 and 15, the risk rises to around 61%. This is a stronger effect than growing up in a deprived neighbourhood.

It has led researchers behind the study to suggest a settled home environment -- in terms of location -- during childhood may be one way of protecting against future mental health issues.

The study was carried out by researchers from Aarhus University (Denmark), the University of Plymouth (UK) and the University of Manchester (UK).

Professor Clive Sabel, Professor of Big Data and Spatial Science at the University of Plymouth and former Director of the Big Data Centre for Environment and Health at Aarhus University, is the study's lead author.

He said: "We know there are a number of factors which lead to a person being diagnosed with a mental illness. However, this is the first evidence to suggest that moving to a new neighbourhood during childhood is among them, and we believe the numbers we are seeing could be the tip of the iceberg. During those formative years, children are building their social networks through school, sports groups or other activities. Each time they have to adapt to something new it can be disruptive, so we potentially need to find new ways to help people overcome those challenges."

Estimates have suggested up to 13% of the world's population are living with some form of mental health condition, with the global economic burden of that predicted to rise to $6 trillion by 2030.

The causes of such conditions are complex and multifaceted including a number of biological, socioeconomic and psychological factors, but with mounting evidence that individuals' natural, built and social environments are related to mental health.

Existing studies across the world have found that children who move more frequently from birth until their mid-teens are more likely to experience adverse outcomes including attempted suicide, violent criminality, mental illness and substance misuse.

And while its focus was on a significant proportion of the Danish population, the studies authors say they would expect to find similar outcomes across many parts of the world.

Professor Sabel added: "This study emphasises the importance of global policies which enable and support settled childhoods, but ones that take into account regional and cultural identities. However, based on our findings, we also believe particular groups of young people may be at heightened risk. Young people in care often face multiple moves and are potentially being placed under additional pressures. Then there are military children, who move regularly depending on where their parents are stationed. This study would suggest they, and other such children, may need additional assistance to prevent the development of mental illness in later life."