Teen smoking could lead to adult depression: study

WASHINGTON, Jan. 29 (Chinese media) -- Teenagers who smoke

could be setting themselves up for depression later in life, according to a

groundbreaking new Florida State University study.

Psychology Professor Carlos Bolanos and a team of researchers found that nicotine given to adolescent rats induced a depression-like state characterized by a lack of pleasure and heightened sensitivity to stress in their adult lives.

Teenagers who smoke could be setting themselves up for depression later in life, according to a groundbreaking new Florida State University study.(File Photo)
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The findings, published online on Thursday in the

journal Neuropsychopharmacology, suggest that the same may be true for humans.

"This study is unique because it is the first one to

show that nicotine exposure early in life can have long-term neurobiological

consequences evidenced in mood disorders," Bolanos said. "In addition, the study

indicates that even brief exposure to nicotine increases risk for mood disorders

later in life."

The Florida State University researchers injected

adolescent rats twice daily with either nicotine or saline for 15 days. After

the treatment period ended, they subjected the rats to several experiments

designed to find out how they would react to stressful situations as well as how

they would respond to the offering of rewards.

They found that behavioral changes symptomatic of

depression can emerge after one week of nicotine cessation and -- most

surprising -- that even a single day of nicotine exposure during adolescence can

have long-lasting effects.

"Some of the animals in our study were exposed to

nicotine once and never saw the drug again," Bolanos said. "It was surprising to

us to discover that a single day of nicotine exposure could potentially have

such long-term negative consequences."

The rats that were exposed to nicotine engaged in

behaviors symptomatic of depression and anxiety, including repetitive grooming,

decreased consumption of rewards offered in the form of sugary drinks and

becoming immobile in stressful situations instead of engaging in typical

escape-like behaviors. The researchers were able to alleviate the rats' symptoms

with antidepressant drugs or, ironically, more nicotine.

Interestingly, adult rodents that were exposed to the

same nicotine regimen as the adolescents did not display depression-like traits.

It is not known exactly how nicotine works on the brain and nervous system to

induce these effects, but exposure has toxic effects in several brain regions

and neurotransmitter systems at distinct periods of development, Bolanos said.

Because various neurotransmitter systems in the brain

continue to develop throughout adolescence, the researchers theorize that

nicotine may negatively influence these systems resulting in altered

functionality later in life. The study's findings underscore the need for

further research into how this process occurs.

Scientists have long known there is a connection

between smoking and mood disorders, but they have not been able to say for sure

that one causes the other because there are so many factors influencing human

behavior. This study provides support for the idea that smoking can induce

symptoms of depression, and paradoxically, can also be a way of managing those

same symptoms and enhancing the risk for addiction.

"The message to young people of course is don't smoke

and don't even try it," Bolanos said. "If they do smoke, they need to be aware

of the potentially long-term effects that recreational or even occasional

cigarette smoking can have on their systems."