Over-the-Counter Drugs Linked to Increased Chance of “Dementia”

A new study has linked the use of common medications, including many over-the-counter treatments for conditions such as insomnia or even hay fever, to dementia. The types of medications in question are drugs that have an "anticholinergic" effect, but experts have said that people should not panic or stop taking their medications just yet.

In a study conducted in the United States and published in the journal JAMA Internal Medicine, researchers looked at older individuals who have taken drugs every day for three or more years, and found that there is an increased risk of dementia for people taking higher doses of these drugs and people taking them for a prolonged period of time.

All drugs come with side effects and anticholinergic drugs are no different.  These drugs block a neurotransmitter called acetylcholine that could possibly reduce attention span and cause memory problems, as well as dry mouth in patients.  But researchers believe there could be additional risks such as increased chance of dementia in older patients, who have been taking the drugs for a prolonged period of time.

Dr. Shelly Gray and colleagues from the University of Washington followed the health of 3,434 people aged 65 and older who had no signs of dementia at the beginning of the study.  They examined the medical and pharmacy records of the participants to determine who had been given drugs with an anticholinergic effect, looking at the dose and frequency then comparing this data with dementia diagnosis over the next decade.

The study estimated that people taking at least 10 mg/day of doxepin (antidepressant), four mg/day of diphenhydramine (a sleep aid), or five mg/day of oxybutynin (a urinary incontinence drug) for more than three years would be at greater risk of developing dementia.

Is this new study definitive?  No, not according to Dr. Simon Ridley, head of research at Alzheimer's Research UK.  "I'd still say not at this point, because we'd want to see another study done, perhaps in a slightly different way" Ridley says.

"There have been concerns that regular use by older people of certain medications with anticholinergic effects, such as sleep aids and hay-fever treatments, can increase the risk of dementia in certain circumstances, which this study supports" Dr. Doug Brown, of the UK Alzheimer's Society, says. "However, it is still unclear whether this is the case and if so, whether the effects seen are a result of long-term use or several episodes of short-term use. More robust research is needed to understand what the potential dangers are, and if some drugs are more likely to have this effect than others."

"We would encourage doctors and pharmacists to be aware of this potential link and would advise anyone concerned about this to speak to their GP before stopping any medication."

While the study may not be definitive, researchers say doctors and pharmacists might want to take precautionary approaches and offer other treatments when possible.  If there is no alternative, they could give lower dosages for shorter periods of time.