And in a recent large-scale, case-control study involving nearly 300,000 people, British researchers found statistically significant associations between different types of anticholinergic drugs and the risk of dementia. Their findings convinced the researchers to recommend caution when prescribing these medications to patients, especially middle-aged and older adults.
Anticholinergic medications are a class of drugs designed to block the activities of a brain chemical (neurotransmitter) called acetylcholine. Acetylcholine is produced by neurons to facilitate the transmission of signals from one cell to another. In the central nervous system, this neurotransmitter helps modulate responses involved in arousal, attention, learning, memory, motivation and sleep. In fact, decreased acetylcholine levels is often associated with Alzheimer's disease. In the peripheral nervous system, acetylcholine can be found in motor neurons and helps make various functions -- from muscle contraction to blood vessel dilation -- possible.
Anticholinergic drugs are often used to inhibit nerve impulses, which can help suppress involuntary movements associated with certain diseases. For instance, people with Parkinson's disease suffer from dyskinesia, a disorder characterized by muscle movements that are difficult to control. These movements include twitches, jerks and twisting or writhing movements. Parkinson's sufferers are given anticholinergic medications to stop dyskinesia affecting their arms, legs or torso.
According to previous studies, almost 40 percent of older adults rely on anticholinergic drugs as treatment for conditions that affect the gastrointestinal tract, lungs and urinary tract. But while antispasmodics, anti-muscarinics (for bladder problems) and anti-parkinsonian drugs may perform as intended, other medications, such as first-generation antihistamines, tricylic antidepressants and some antipsychotics, have unintended anticholinergic effects. Unfortunately, the cumulative use of these drugs can cause pathological changes in the brain, which can lead to serious and irreversible cognitive deficits, such as dementia.
Two recent studies, both published in JAMA Internal Medicine, explored the link between anticholinergic medicine and dementia risk. In the first one, American researchers analyzed data collected from 3,434 older adults who were observed from 2004 to 2012. The study participants were aged 65 years or older and had no dementia when they were recruited. They were followed up every two years to determine their cumulative anticholinergic exposure.
The researchers reported that the most commonly used anticholinergic drugs by the participants were tricyclic antidepressants, first-generation antihistamines and bladder anti-muscarinics. During a mean follow-up of 7.3 years, 797 participants developed dementia, nearly 80 percent of which were diagnosed as Alzheimer's disease. (Related: Making healthy lifestyle choices can prevent the onset of dementia.)
The researchers noted that with higher cumulative use of anticholinergic medications, the individual risk of dementia also increased. This trend held true for all subsequent analyses; hence the researchers emphasized the need to raise awareness among healthcare professionals and older adults, so the use of these dangerous medicines can be minimized over time.
In the second, much-larger study, a team of British researchers evaluated the exposure to anticholinergic drugs of 58,769 participants with dementia and 225,574 healthy controls. The participants were aged 55 years or older and were matched by age, sex, general practice and calendar time. The researchers used data on prescriptions for 56 drugs with anticholinergic properties to measure the participants' cumulative anticholinergic drug exposure. The study lasted for two years.
The researchers found significant increases in dementia risk associated with the use of anticholinergic antidepressants, anti-parkinsonian drugs, antipsychotics, anti-muscarinic drugs and anti-epileptic drugs. The results remained the same even when exposures were restricted to windows of three to 13 years. The researchers also noted that the associations were stronger in cases diagnosed before the age of 80. Taken together, these findings confirm that long-term use of different types of anticholinergic drugs does increase a person's risk of dementia.
Learn about effective alternatives to different anticholinergic drugs at NaturalMedicine.news.