By Mili Jayadeep | Science Editor
Alzheimer’s disease (AD) is a neurodegenerative disease that makes up approximately 60% of diagnoses of dementia in the UK. It generally occurs in the older generation, typically aged over 65. This condition becomes progressively worse over time causing symptoms including memory impairments and difficulty in many day to day tasks that involve thinking, reasoning, language and even perception.
Acetylcholine is a brain chemical that is responsible for transmitting information and crucial to memory functioning in the brain. However, in people with Alzheimer’s, there is often a reduction in the production of acetylcholine hence hindering their ability to process information effectively.
A new study conducted by scientists at the University of California San Diego School of Medicine, reports that a common class of medications used for a variety of conditions including allergy, colds, high blood pressure and even urinary problems is associated with a greater risk of cognitive impairment. The findings in the study was recently published in the medical journal, Neurology shows that the risk is particularly great in older people at risk for AD.
The study was based on 688 adults with equal gender distribution and an average age of 74. 1/3 of the study participants were noted to be on medications, which are anticholinergic in nature. Of these participants, each were on an average of 4.7 anticholinergic medications. These work by blocking the chemical messenger, acetylcholine. The lack of this neurotransmitter on the brain results in the inhibition of parasympathetic nerve impulses, responsible for muscle contraction in the gastrointestinal system, the lungs and also in activities such as urination, digestion and salivation in those taking these medications. Cognition tests at the start of the study showed normal memory and thinking in all members of the study. Thorough follow-up cognitive tests were also yearly conducted for ten years.
The results showed that those that took at least one anticholinergic medication were at a 47% increased chance of developing mild cognitive impairment (MCI) when compared to those not who did not take those medications. MCI can develop into AD and also increases the risk of developing dementia according to other studies.
Associate professor in the Department of Psychiatry at UC San Diego School of Medicine and senior author, Lisa Delano-Wood explained the significance of these findings:
“This study, led by Alexandra Weigand, suggests that reducing anticholinergic drug use before cognitive problems appear may be important for preventing future negative effects on memory and thinking skills, especially for people at greater risk for Alzheimer’s disease.”
The researchers studied the cerebrospinal fluid of participants to note the presence of AD biomarkers, involving special proteins and those with a known genetic risk factor for AD. The biomarkers were either in the form of certain proteins or known genetic factors. People with biomarkers taking anticholinergic drugs were four times more likely to develop MCI than those who had no markers and did not take such medications. Likewise, those with a genetic risk factor taking these medications was at a two and a half times greater risk for MCI than those who did not. Study author, Weigand explained,
“We believe this interaction between anticholinergic drugs and Alzheimer’s risk biomarkers acts in a ‘double hit’ manner…In the first hit, Alzheimer’s biomarkers indicate that pathology has started to accumulate in and degenerate a small region called the basal forebrain that produces the chemical acetylcholine, which promotes thinking and memory. In the second hit, anticholinergic drugs further deplete the brain’s store of acetylcholine. This combined effect most significantly impacts a person’s thinking and memory.”
Anticholinergic drugs can either be prescribed or bought over the counter. It was also noted that by the researchers that improper knowledge of administration dosages could be responsible. People may be taking much higher doses of anticholinergic medications than the recommended dose for effective treatment. Weigand cautioned,
“This points to a potential area for improvement since reducing anticholinergic drug dosages may possibly delay cognitive decline…It’s important for older adults who take anticholinergic medications to regularly consult with their doctors and discuss medication use and dosages.”
Prior studies support this study’s findings of the association of anticholinergic medications to increasing AD risk. However, more research is needed before changes can be seen in prescription and administration of anticholinergic medications. Delano Wood says,
“Clinical ‘deprescribing’ studies are currently underway at certain research sites across the nation in an effort to investigate whether reducing or stopping use of these drugs does, in fact, lead to reductions in progressive cognitive impairment,”
Alzheimer’s disease drastically affects the lives of many older adults; The cognitive impairment seen in individuals with dementia can be debilitating to both the individual and their family. The link shown between common medications and its role in increasing AD risk, highlights the importance of further research to help prevent and halt cognitive decline.Science and Technology Mili Jayadeep