Memory loss isn't always an inevitable sign of getting old – in some cases, common medications that seniors take to treat insomnia, anxiety, or even allergies could be to blame.

"Seniors can play an important role in reducing the risks associated with these medications,” Montreal Geriatric University Institute researcher Cara Tannenbaum said in a statement Tuesday.

Tannenbaum and her colleagues recently investigated what kinds of medication are most likely to affect both memory and concentration. In a meta-analysis of 162 experiments on various drugs, Tannenbaum concluded that the recurrent use of several kinds of medications can have impacts on cognitive function.

Sixty-eight of the studies they examined focused on benzodiazepines, which are often used to treat insomnia and anxiety. Consistently, these medications led to impared memory and concentration, with stronger impacts at higher doses. Tannenbaum says her findings confirm recent recommendations from the American Geriatric Society that seniors avoid tricyclic antidepressants, certain antihistamines and all sleeping pills.

“Patients need this information so that they are more comfortable talking to their doctors and pharmacists about safer pharmacological or non-pharmacological treatment options," Tannenbaum said.

Benzodiazepines aren't the only kinds of medication that could impact memory. In February, the U.S. Food and Drug Administration added new warnings about memory loss and an increased risk for Type 2 diabetes to the labels of cholesterol-fighting statin medications.

Popular drugs like Lipitor, Crestor and Vytorin fell under the scope of February's decision by the FDA, which was based on results from new clinical trials and reports of side effects from patients, doctors and pharmaceutical companies.

Memory loss associated with statins tends to go away once a patient stops using the drug, the FDA said.

The link between anti-cholesterol medication and memory impairment becomes somewhat less surprising when you consider how fatty brain tissue is. While high levels of cholesterol are bad for your heart, they help form vital neural connections in the brain.

“We can’t understand how a drug that affects such an important pathway would not have adverse reactions,” Ralph Edwards, former director of the World Health Organization’s drug-monitoring center in Sweden told Scientific American in 2010.

Many drugs that cause mild cognitive impairment are anti-cholinergic, meaning that they inhibit the activity of the neurotransmitter acetylcholine.

Some drugs are specifically taken for their anti-cholinergic effects and can help relieve bladder irritability or intestinal cramping. But patients, doctors and pharmacists may not be aware of the anti-cholinergic activity of other kinds of drugs, like antidepressants and antihistamines.

Tannenbaum acknowledges that each person should be dealt with individually.

"Despite the known risks, it may be better for some patients to continue their medication instead of having to live with intolerable symptoms,” she says. “Each individual has a right to make an informed choice based on preference and a thorough understanding of the effects the medications may have on their memory and function."

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