Studies suggest that the simultaneous use of multiple medications is associated with an increased risk of dementia.
But the patterns of medication use in older adults before the diagnosis of dementia are not well-characterized.
A recent study published in Aging and Disease used machine learning algorithms to characterize changes in the patterns of medication use and co-occurring chronic conditions during the 20-year period before a dementia diagnosis.
The results showed that patterns of medication use were similar as subjects approached the date of their diagnosis, highlighting a need for a more integrated approach to care for individuals with dementia.
“Given the rise in dementia cases internationally, the need to understand how patterns of polypharmacy evolve before and after a dementia diagnosis is important for devising a safe treatment program for each patient,” study author Shang-Ming Zhou, BSc, MSc, Ph.D., a professor of e-Health at the School of Nursing and Midwifery at the University of Plymouth in the United Kingdom, said in a news release.
“Our aim in this study was to help doctors find ways to prescribe multiple items of dementia medication safely and without reducing their effectiveness. The use of machine learning has been vital in helping us understand how these patterns develop, and our hope is we can now use this knowledge to treat patients.”
– Shang-Ming Zhou, BSc, MSc, Ph.D., lead author of the study
As people get older, some may experience a greater number of co-occurring chronic health problems.
The presence of multiple chronic conditions is associated with an increase in the concomitant use of multiple prescription medications.
In addition, healthcare providers may also prescribe medications as a preventive measure to reduce the risk of occurrence of chronic conditions such as cardiovascular disease (CVD) in the future or prevent their progression.
With an increase in the number of preventive medications that are simultaneously used, the benefit derived due to the use of each medication often declines.
The increase in the number of medications can also increase the risk of adverse effects and interactions between the different medications. In addition, polypharmacy is associated with an increase in the risk of drug-disease interactions, whereby the medications used to treat one disease can worsen the symptoms of another condition.
Consistent with this, polypharmacy is associated with negative clinical outcomes, including an increased risk of hospitalization and death among older adults. Moreover, treatment guidelines for various conditions do not necessarily account for physiological changes that occur with aging.
The use of multiple medications may also make it challenging for the person with dementia to adhere to the prescribed schedule.
However, researchers caution that only the inappropriate use of multiple medications — such as combinations that may interact with or cause additive side effects — is specifically harmful.
By contrast, the use of multiple medications can be effective if the combination is appropriately prescribed by an interdisciplinary team using the best available evidence.
Undertreatment can be as problematic as over-prescription, and researchers have noted that it is essential to ensure that older individuals receive the optimal combination of medications that are specific to their needs.
Dementia is a neurological condition characterized by a gradual and progressive decline in cognitive function.
In addition to deficits in thinking, memory, judgment, and language, individuals with dementia may also show behavioral and psychological symptoms such as depression, agitation, and anxiety. Thus, individuals with dementia are often prescribed multiple medications to manage these symptoms.
A 2019 meta-analysis showed that the simultaneous use of multiple medications was associated with an increased risk of dementia.
What’s more, the use of one or more anticholinergic drugs that are used to treat conditions such as cardiovascular diseases, respiratory disorders, and overactive bladder is associated with an increased risk of cognitive impairment and dementia.
Thus, it is essential to characterize the patterns of medication use before the diagnosis of dementia to better understand the role of these patterns in the development of dementia and reduce the risk of drug-drug interactions.
In the present study, the researchers examined the patterns of polypharmacy, defined as the intake of three or more medicines, over a 20-year period before the diagnosis of dementia in 33,451 individuals.
The researchers used electronic records from primary healthcare providers to obtain data on the prescription of medications and disease diagnosis during the 20-year period prior to the diagnosis of dementia. The 20-year period before the dementia diagnosis was divided into four periods of 5 years each.
The researchers found that the prevalence of individuals using three or more medications increased as their age increased, and they approached the date of dementia diagnosis.
The fraction of individuals living with dementia using three or more medications increased from 5.5% between 16 to 20 years before the dementia diagnosis to 82% during the five-year period preceding the diagnosis.
The researchers then used algorithms to identify clusters of medications that were commonly used together in each of the four time periods. For instance, during the 5-year period prior to the diagnosis of dementia, the researchers identified three distinct patterns.
The first cluster accounted for 66% of subjects and included medications for respiratory and urinary tract infections, osteoarthritis and other related conditions, and cardiovascular diseases.
The second cluster included 22% of subjects and included medications for diabetes, depression, and anxiety in addition to those present in the first cluster.
In addition, a third cluster accounted for 2% of the subjects and included medications for osteoarthritis and related conditions.
Among these clusters, the researchers found medications that have been shown to interact with each other or worsen the symptoms of other chronic conditions.
Similarly, the researchers identified multiple clusters of medications for the remaining three time periods.
As the time from the date of dementia diagnosis increased, the number of clusters or patterns of medication use also increased. For example, the researchers identified 6 clusters for the time window from 11 to 15 years before the date of dementia diagnosis in comparison with 3 clusters during the 5-year period prior to the diagnosis.
As the time from dementia diagnosis increased, each cluster consisted of fewer medicines, and the number of individuals in each cluster became smaller.
Thus, during the 5-year period closest to the dementia diagnosis, two clusters, especially the first cluster, included a large number of medicines and accounted for a majority of individuals (66%).
The larger number of medicines in these clusters suggests that the number of co-occurring conditions increased as subjects moved closer to the date of dementia diagnosis.
Moreover, the larger number of subjects in these clusters suggests they were more likely to show similar patterns of co-occurring chronic conditions and polypharmacy as they approached the date of dementia diagnosis.
These results highlight the importance of an integrated or holistic approach to care for individuals with dementia.
Dr. David A. Merrill, Ph.D., psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center in Santa Monica, CA, not involved in the study, told Medical News Today:
“The brain is much like the kidney and the heart in terms of being an end-organ that is significantly affected by systemic diseases and the treatments for those conditions. It’s important to take the effects of medication on the whole body into account, even when treating a localized infection like bronchitis or aches and pains from arthritis. The medication choices made over the years with a patient can significantly impact the course of heart and kidney disease and brain health.”
The researchers noted that their study did not examine patterns of polypharmacy in individuals without dementia, and some of the patterns observed in the study could be due to the effects of aging.
Thus, further research is needed to establish causality between the patterns of polypharmacy characterized in the study and dementia.



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