A fascinating newly released study has shed some light on the long running "nature versus nurture" debate. The study has found that newborn babies who exhibit highly reactive tendencies have a higher chance of developing symptoms of anxiety and depression later in life.
The nature–nurture debate has been prevalent for many decades. The theory in the 1940’s was that babies were born with a clean slate as far as personality and temperament were concerned and personality was formed from the environment. This week, the Molecular Psychiatry Journal has printed results from a research study into this old question. Are our personalities and behaviours determined by our biological make-up, are they nurtured by our environment, or can it be a mixture of the two? The researchers decided to go one step further and attempted to determine whether mental illnesses such as anxiety could be due to genetics or nurtured by external forces.
The likelihood of anxiety and symptoms of depression in later life
This study has been taking place over a number of years as it followed 135 children from babies to adulthood. Researchers found that behaviours which were prevalent in babies only a few months old, were comparable to behaviours witnessed in adult life. The studies found that for boys at least, being a fussy, reactive infant in the first few months of life could be associated with a stronger neurological reaction to unfamiliar faces at the age of 18. The researchers viewed this link as a sign of a propensity towards social anxiety and even depression in later life.
“High reactive” and “low reactive” infants
When the babies were still very young (4 months old) researchers created two categories: “low reactive” and “high reactive” individuals. The “high reactive group” referred to babies who fussed and cried when presented with loud noises or unfamiliar smells, whereas “low reactive,” showed no overt fear or agitation when presented with the same stimuli. Researchers suspected that the “high reactive” infants would continue to have a negative response to unfamiliar stimuli up through adulthood, though as adults, this fear of the unfamiliar might manifest as social anxiety, generalized anxiety or depression. When the researchers analysed the parts of the brain that signals threat and novelty, it was the individuals (and especially the boys) who had been classed as “high reactive” as babies who had the greater responses when shown unfamiliar faces. For instance, if a “high reactive” individual were to walk into a room full of strangers, their brains would interpret the situation as a threat.
Results can help with depression treatment
Dr. Carl Schwartz, the Massachusetts General Hospital psychiatrist who led the study explained that what these results were showing was that babies who are highly reactive at birth are likely to continue with this behaviour into adulthood. Though it is not in any way determining high anxiety in late life it shows how difficult it maybe for an individual such as this to start exhibiting extrovert behaviour. It was felt that having this knowledge at hand from an early age could help society nurture individuals into living with a certain temperament.