(CBS News) Adults who drink later in life may be more likely to experience cognitive declines that could lead to dementia, according to two new studies.
The research, presented on July 18 at the Alzheimer's Association International Conference 2012 in Vancouver, Canada, may point to another risk factor adults might want to avoid to help stave off Alzheimer's.
The first of the studies looked at whether moderate alcohol consumption affected cognitive abilities in 1,300 women who were 65 and older. Researchers at the University of California, San Francisco, tracked these women for 20 years, measuring their alcohol use and testing them for mild cognitive impairment or dementia by the study's completion. Mild cognitive impairment (MCI) refers to the stage between cognitive decline that's typical for aging adults and the more pronounced decline of dementia.
At the start of the study, 41 percent of the women didn't drink at all, 50 percent were light drinkers (consuming between zero and seven alcoholic drinks per week), and 9 percent were considered moderate drinkers (seven to 14 drinks per week). Women who drank 14 or more drinks were excluded from the study pool.
The researchers found that women who reported drinking more towards the beginning of the study were 30 percent more likely to develop cognitive impairment compared with non-drinkers. Moderate drinkers at the start of the study had a similar risk, however moderate drinkers who started drinking later in life towards the end of the 20-year study period were 60 percent more likely to experience a cognitive decline. Women who were nondrinkers at the start of the study who changed course over time were 200 percent more likely to have cognitive declines.
Moderate drinking is often tied to health benefits in women, including two new studies that showed women who drink in moderation are less likely to develop rheumatoid arthritis or bone fractures suggestive of osteoporosis. Other studies have tied moderate drinking in women to a protective benefit against heart conditions and strokes.
"In this group of older women, moderate alcohol consumption was not protective," study author Tina Hoang, a researcher at UCSF's Veteran's Health Research Institute, said in a press release. "We found that heavier use earlier in life, moderate use in late-life, and transitioning to drinking in late-life were associated with an increased risk of developing cognitive impairment. These findings suggest that alcohol use in late-life may not be beneficial for cognitive function in older women."
Hoang said the effects may be explained by older adults having brains more vulnerable to the effects of alcohol, or factors contributing to why someone might drink - such as coping or loss - that might play a role.
"Clinicians should carefully assess their older patients for both how much they drink and any changes in patterns of alcohol use," Hoang said.
The second study, also presented today at the conference, looked at the effects of binge drinking - as defined as having four or five drinks in a short time period on a single occasion - in older adults and whether that played a role in cognitive decline. British researchers at the University of Exeter tracked 5,075 U.S. adults who were 50 and older to see what binging did to their cognition and mood. The participants were tracked from 2002 to 2010, and researchers found about 8 percent of men and 1.5 percent of women engaged in binge drinking once a month or more, while about 4 percent of men and 0.5 percent of women binge drank twice a month or more.
Further analysis revealed that participants who binged once per month were 62 percent more likely to experience the highest levels of cognitive decline and were 27 percent more likely to be among the group experiencing the worst levels of memory decline. Those who reported binging twice per month or more were 147 percent more likely to experience the highest cognitive decline and 149 percent more likely to experience the greatest memory loss.
"These differences were present even when we took into account other factors known to be related to cognitive decline such as age and level of education," study author Dr. Ian Lang, a researcher at Peninsula College of Medicine and Dentistry at Exeter, said in a press release.
A January report from the Centers for Disease Control and Prevention on the state of binge drinking in the U.S. found 38 million U.S. adults binge drink, about one in six people, and adults 65 and over were found to binge drink an average of five or six times a month, more often than other age groups.
"Policymakers and public health specialists should know that binge drinking is not just a problem among adolescents and younger adults; we have to start thinking about older people when we are planning interventions to reduce binge drinking," Lang said.