Prolonged Use of Anticholinergic Drugs Could Increase Dementia Risk

Prolonged use of anticholinergic agents, especially in adults over the age of 45 years may increase the risk of dementia according to a recent study conducted by the University of East Anglia, UK. The findings of the study appear in the British Medical Journal.

Aim of Study

• Numerous earlier studies have reported associations between use of anticholinergic drugs and cognitive decline and dementia later, but it is not clearly understood whether the dementia was actually due to the drugs or the underlying condition for which they were prescribed.

Details of Study

• The team studied data from the UK's Clinical Practice Research Database of 40,770 patients between the ages of 65 to 99 years who were diagnosed with dementia between April 2006 and July 2015.
• Every case (dementia) patient was matched to up to seven control patients of the same age and sex, but not suffering from dementia.
• Drugs used to treat them were scored based on their anticholinergic activity using the Anticholinergic Cognitive Burden (ACB) scale. An ACB score of 1 meant possible
• anticholinergic activity, while a score of 2 or 3 meant being definitely anticholinergic.
• Daily doses of each drug were then compared for both cases and controls with an exposure period of 4 to 20 years before a diagnosis of dementia was made.
• During this period, a total of 14,453 (35%) cases and 86,403 (30%) controls were taking at least one anticholinergic drug with an ACB score of 3.
• After ruling out possible influencing factors, the team found that anti-depressants, anti-Parkinson's disease drugs, and drugs to treat urinary incontinence with definite anticholinergic activity (ACB score of 3) upped dementia risk up to 20 years after exposure.
• However, an increased risk was not found for drugs with possible anticholinergic activity (ACB score of 1) or in gastrointestinal or respiratory drugs having definite anticholinergic activity (ACB score of 3).
• Other anti-depressants (particularly selective serotonin reuptake inhibitors) with an ACB score of 1 were linked to dementia, but only closer to the time of prescription, which may not represent a direct causal link, feel the study team.

The authors admit that a firm causal link cannot be established and this is mainly an observational study. Certain limitations included mis-classification of dementia in patients and lack of data on the severity of depression. However, this study was the largest of its kind till date and accounted for several potential influential factors.

Takeaway from Study

• The scientists believe that the association might be "caused by a class specific effect, or by agents being used for very early symptoms of dementia" and further research into the effects of specific drug classes is necessary for more clarity.
• However, they feel clinicians "should continue to be vigilant with respect to the use of anticholinergic drugs, and should consider the risk of long term cognitive effects, as well as short term effects, associated with specific drug classes when performing their risk-benefit analysis."

In an editorial linked to the study, Professor Shelly Gray at the University of Washington and Professor Joseph Hanlon at the University of Pittsburgh, say this research "raises important issues about the best way to summarise anticholinergic burden for future research."

What is Dementia?

Dementia refers to a group of symptoms caused by disorders affecting the brain. These symptoms may include memory loss and difficulties with thinking and understanding, problem-solving or language, and can become severe enough to affect a person's ability to perform daily activities. Dementia may also be associated with changes in mood or behaviour.

Over-the-Counter Anticholinergic Drugs Exacerbate Dementia Risk
Drugs used for hay fever medication, asthma and sleeping pills can lead to reduced brain size and cognition in senior adults.

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Dementia is a progressive condition, meaning the symptoms will gradually get worse over time as more brain cells are destroyed and eventually die. It is not a specific disease per se but can be caused by several underlying conditions such as Alzheimer's disease, Parkinson disease, thyroid disease, sleep disorders and certain vitamin deficiencies. A complete evaluation is therefore necessary to identify the cause and treat as appropriate.

In conclusion, the consensus among the scientists appears to be that anticholinergic agents are best avoided in older adults.

"Specifically, for most highly anticholinergic drugs, non-pharmacological and pharmacological alternatives are available and should be considered," they conclude.

References :

1. Anticholinergic - (https://en.wikipedia.org/wiki/Anticholinergic#Medical_uses)

Source: Medindia