What happens to memory when alcohol use meets early cognitive decline? A new study explores how drinking patterns may shape the way memory errors appear in people already at risk.
Scientists have long understood that alcohol use can interfere with memory. It can make it harder to encode new information and easier to mix up or misremember what鈥檚 already been learned.
As populations age and more people begin to experience cognitive decline, the impact of alcohol takes on new stakes. However, Assistant Professor and clinical neuropsychologist Sara Pishdadian, who teaches in the Faculty of Health's Department of Psychology, says relatively little research has examined how patterns of alcohol use affect older adults 鈥 particularly those already living with mild cognitive impairment (MCI), where memory systems are more vulnerable.
In partnership with colleagues at the Centre for Addiction and Mental Health, Pishdadian set out to address that gap. 鈥淲e were motivated to understand how drinking habits impact individuals鈥 memory abilities, particularly those at an increased risk of developing dementia.鈥
Through research, in the Journal of Alzheimer鈥檚 Disease, Pishdadian and collaborators focused on a specific type of recall error known as intrusions.
Remembering a word involves multiple steps, including learning it, holding onto it and pulling it back when needed. When those steps falter, people don鈥檛 just forget 鈥 they sometimes fill in gaps with mistakes. In verbal memory tests, those slip ups are known as intrusions: recalling words that don鈥檛 belong, come from the wrong list or are loosely related. They offer a window into how well the brain monitors and controls retrieval.
Building on this, the researchers set out to examine whether patterns of alcohol use are linked to a distinct pattern of errors in older adults with MCI 鈥 specifically, whether differences in drinking habits are associated with greater difficulty filtering out or suppressing irrelevant information during recall.
To explore this, the team drew on cognitive testing and clinical data from two large, long-running Canadian research initiatives: COMPASS-ND, a national study of neurodegenerative disease, and the Ontario Neurodegenerative Disease Research Initiative, which follows people living with conditions such as Alzheimer鈥檚 disease and vascular cognitive impairment.
The researchers focused on 521 adults with MCI caused by either Alzheimer鈥檚 disease or cerebrovascular disease, drawing on data from the two national studies. Participants were grouped based on self-reported drinking habits: non-drinkers; those consuming up to six drinks per week; those reporting seven or more. None of the participants had a diagnosed alcohol use disorder.
All participants had previously completed the Rey Auditory Verbal Learning Test 鈥 a widely used assessment measure in which people learn a list of words, are interrupted with a competing list and then try to recall the original words. Because of how it is structured, the test allows researchers to assess not just how much someone remembers but also how well they manage interference.
The team also took a closer look at intrusion errors in the data 鈥 examining not just whether people made mistakes but also what kinds of incorrect words they recalled and when.
When they analyzed those results, a more nuanced pattern emerged. Most participants made at least one intrusion, but differences became clearer when the researchers looked at when they happened. People in the higher alcohol use group were especially prone to making these mistakes after being exposed to new, competing information. In other words, once distracting material entered the picture, they had more trouble keeping it from spilling into their recall of the original list.
This pattern points to a problem with cognitive control rather than memory itself. The issue wasn鈥檛 that participants couldn鈥檛 learn or retain the words 鈥 it was that they struggled to block out competing information when trying to recall them. The key signal was when mistakes happened, clustering after new, interfering material had been introduced and when the cognitive system was under greater demand. The difficulty lay in filtering out distractions, a function tied to the brain鈥檚 executive control systems.
This matters because executive control can already be more fragile in people with MCI. The findings suggest that higher levels of alcohol use may cause additional strain, making it harder to manage interference even when overall memory performance appears similar.
Pishdadian says the findings have important implications. The insights gained into how subtle problems in retrieval control can be detected may help improve how cognitive issues are assessed and diagnosed. She notes that they could shift how MCI is monitored, as memory clinics typically focus on how much a patient can recall. Tracking intrusion errors could reveal more subtle vulnerabilities, particularly in those who drink alcohol.
The research may also inform more proactive support. 鈥淭he findings highlight the importance of cognitive rehabilitation programs that help individuals with MCI improve how they learn and recall information,鈥 says Pishdadian, noting that targeted exercises built on new insights could help reduce interference-related slips.
While the study is observational and does not prove causation, it adds to growing evidence that alcohol and neurodegenerative disease interact. Because alcohol consumption is a modifiable behaviour, the findings may help raise awareness among people with MCI who continue to drink and support more informed decisions around prevention and care.
Pishdadian also hopes the work can open the door to further research. 鈥淭hese results show how looking more closely at patterns in memory errors can yield important insights for people with MCI,鈥 she says.