Diabetes, smoking linked to deposits in brain region tied to memory

People who smoke or have diabetes may be more likely to have calcium deposits in brain regions crucial for memory, a Dutch study suggests. 

The deposits were not associated with lower cognitive function, however. 

Researchers examined cognitive test results and brain scans for 1,991 patients visiting a memory clinic at a Dutch hospital from 2009 to 2015. Overall, 380 patients, or about 19 per cent, had calcification, or abnormal buildup of calcium, in the hippocampus, the region of the brain important for short-term and long-term memory. 

Diabetics and smokers were about 50 per cent more likely to have calcification in this region of the brain than other participants in the study, the researchers note in Radiology. 

The hippocampus is typically damaged in people who develop dementia and Alzheimer’s disease. 

“The hippocampus is an important area in the brain for memory storage, so we thought that calcifications in this area would be related with cognitive problems,” said lead study author Dr Esther de Brouwer of the University Medical Centre Utrecht in the Netherlands. 

But in these volunteers, hippocampal calcifications were not related to cognitive problems, de Brouwer noted in an e-mail. This was a surprise because researchers had expected that calcification might be related to vascular problems common with smoking and diabetes that could contribute to shrinkage of tissue, or atrophy, in the hippocampus and subsequent cognitive decline. 

Because the hippocampus has many layers, it’s possible the calcification didn’t damage the layers involved in memory, de Brouwer said. More research is needed to explore possible links between calcifications and cognitive problems, the study authors conclude. 

Participants in the study were 78 years old on average, although they ranged in age from 45 to 96. 

Each added year of age was associated with a 5 per cent greater risk of calcification in the hippocampus, the study found. 

Overall, 228 participants, or about 12 per cent, were smokers. Once researchers accounted for factors like age, sex, high blood pressure, high cholesterol and diabetes, the smokers in the study were 49 per cent more likely to have calcifications in the hippocampus than nonsmokers. 

A total of 317 participants, or about 16 per cent, had diabetes. After researchers accounted for smoking status and the other factors they examined for smokers, they found diabetics were 50 per cent more likely to have calcifications than participants without diabetes. 

The study wasn’t designed to prove whether or how smoking or diabetes might directly contribute to calcifications in the hippocampus or cognitive problems. 

Even though the study didn’t connect calcifications to worse cognitive abilities, calcium may accumulate more when people have unhealthy blood vessels, said Dr Rebecca Gottesman, a neurology researcher at Johns Hopkins University in Baltimore who wasn’t involved in the study. 

“This study did suggest that the more risk factors you have, the more hippocampal calcification you have,” Gottesman said by e-mail. “And, other studies have suggested that a greater number of these types of risk factors can be associated with worse cognitive outcomes.” 

People should still work to avoid smoking, diabetes and other risk factors for cardiovascular disease, said Dr Andrew Budson, a neurology researcher at Boston University School of Medicine and author of “Seven Steps to Managing Your Memory: What’s Normal, What’s Not, and What to Do About It.”

“Everyone should work to reduce their cardiovascular risk factors by quitting if they are smokers, keeping their sugars under control if they have diabetes, reducing obesity that can be a risk factor for hypertension and diabetes, eating a Mediterranean style diet and engaging in aerobic exercise,” Budson, who wasn’t involved in the study, said by email. 

“Regarding hippocampal calcifications themselves, people shouldn’t worry about them as they are not related to cognitive function,” Budson added.