According to a new study published this week, phobic anxiety, which is triggered by intense fear, contributes to older adults aging quickly.

Although phobic anxieties are especially common in women, 8 percent of Americans have at least one, whether it's a specific fear such as arachnophobia -- fear of spiders -- or an overall uneasiness in certain situations like agoraphobia or social phobia. Researchers from Brigham and Women’s Hospital analyzed survey results and blood samples from 5,243 women, ages 42 to 69, finding that intense phobic anxiety leads to faster biological aging.

"Many people wonder about whether -- and how -- stress can make us age faster," study author Olivia Okereke said in a statement. "So, this study is notable for showing a connection between a common form of psychological stress -- phobic anxiety -- and a plausible mechanism for premature aging."

Okereke and her team found a link between anxiety and shorter telomeres, DNA-protein complexes on the ends of chromosomes that are thought to be the biological markers of aging. Although, phobic anxiety may be a mechanism of early aging according to the study, the research could not "prove cause-and-effect or which problem came first -- the anxiety or shorter telomeres," Okereke said.

So while more research would need to be conducted in order to pinpoint the exact cause, the study's results did confirm that phobic anxiety joins a host of other factors that are linked to faster aging.

In 2005, researchers correlated smoking and obesity with biological aging. A 2009 study on identical twins confirmed the results, while also noting other factors that contribute to accelerated aging.

Even geography has an impact on how quickly people age. A recent report from RealAge.com identified 10 cities whose residents age too fast; Knoxville, Tenn., and Louisville, Ky., topped the list, whereas San Francisco, Cali., and Salt Lake City, Utah, were ranked the highest among cities for staying young.

Check out the gallery to see seven other factors that are known to make people age faster.

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  • Phobic Anxiety

    A new study from researchers at Brigham and Women's Hospital suggests that phobic anxiety can <a href="http://www.huffingtonpost.com/2012/07/12/phobia-age-aging-fear-health-problems_n_1668312.html" target="_hplink">lead to faster biological aging</a>, along with other health-related problems. Author Olivia Okereke and her team studied the relationship between anxiety and telomeres, the DNA-protein complexes at the end of chromosomes that act as biological markers of aging, finding that symptoms of phobic anxiety are linked to shorter telomeres. The study,<a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0040516" target="_hplink"> published in PLoS ONE</a>, established that phobic anxiety is a <a href="http://www.sciencedaily.com/releases/2012/07/120711210102.htm" target="_hplink">plausible mechanism for accelerated aging</a>, but did not prove that anxiety is the root cause. (Image via Shutterstock)

  • Sun Exposure

    Mom was right when she told you to put on some sunscreen at the beach; <a href="http://www.webmd.com/healthy-beauty/news/20090204/genes-vs-behavior-what-makes-us-age" target="_hplink">sun exposure contributes to wrinkles</a> and accelerated external aging. While natural pigments provide some protection, chronic sun exposure can lead to <a href="http://www.nlm.nih.gov/medlineplus/ency/article/004014.htm" target="_hplink">age spots and elastosis</a>, or the breakdown of elastic tissue in the skin that produces leathery skin appearance prevalent among farmers. (Image via AP)

  • Divorce

    Separating from a spouse may also leading to accelerated aging, according to a <a href="http://well.blogs.nytimes.com/2009/02/05/twin-studies-explain-wrinkles-of-aging/" target="_hplink">2009 facial analysis study</a> conducted on sets of identical twins. According to the study led by a team of plastic surgeons, twins who had been divorced <a href="http://www.time.com/time/magazine/article/0,9171,1880645,00.html" target="_hplink">looked noticeably older</a> -- 1.7 years older to be exact -- than twins who had not gone through a divorce. As <em>Time</em>'s John Cloud writes, "you are <a href="http://www.time.com/time/magazine/article/0,9171,1880645,00.html" target="_hplink">better off staying single</a> than getting into a bad relationship." (Image via Alamy)

  • Smoking

    It's no secret that smoking is bad for one's health. The pesky habit can age people faster both on the outside, by <a href="http://news.bbc.co.uk/2/hi/health/1235763.stm" target="_hplink">contributing to wrinkles</a>, and on the inside since smoking is associated with a host of serious health problems. A 2005 study <a href="http://www.webmd.com/smoking-cessation/news/20050624/obesity-smoking-linked-to-faster-aging" target="_hplink">linked smoking with shorter telomere length</a> -- the biological markers of aging -- according to <em>WebMD</em>. More recently, Dr. Bahman Guyuron, who conducted a facial analysis study on pairs of identical twins, also noted that smoking is one of the <a href="http://www.webmd.com/healthy-beauty/news/20090204/genes-vs-behavior-what-makes-us-age" target="_hplink">factors that contributes to accelerated aging</a>. (Image via AP)

  • Sugar

    Poor diets can also contribute to faster aging. High sugar intake, for example, can cause unhealthy weight gain, but the real aging factor is <a href="http://health.howstuffworks.com/skin-care/information/nutrition/sugar-make-us-age.htm" target="_hplink">how one's body recognizes and uses sugar</a>. A 2009 study out of Montreal found that the <a href="http://www.sciencedaily.com/releases/2009/03/090305204328.htm" target="_hplink">lifespan of yeast cells increased</a> as glucose in the system decreased, or if glucose sensors were removed. Either way, over-consumption of sugar, leading to high amounts of sugar on in one's body, is linked to aging. (<a href="http://www.flickr.com/photos/stringy/2536115510/" target="_hplink">Image via Flickr</a>)

  • Antidepressants

    According to the 2009 facial analysis study conducted on identical twins, antidepressants can also lead to accelerated aging. Researchers reviewed photographs of 186 sets of twins, finding that <a href="http://www.time.com/time/magazine/article/0,9171,1880645,00.html" target="_hplink">those who had taken antidepressants often looked older</a> than their respective counterparts who had not. (Image via Getty)

  • Loneliness

    Loneliness in old age may also contribute to people aging more quickly. In a 2011 study, 985 people were assessed on a five-point scale for loneliness. Researchers found that for each point on the scale past the baseline, <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975650/" target="_hplink">motor decline was 40 percent more rapid</a>. More importantly, this increased rate of motor decline was also associated with a 50 percent increased risk of death. So while aging may be accelerated by divorce, loneliness is also a crucial aging factor. (Image via Shutterstock)