Dementia is a major public health problem worldwide. One focus of dementia research has been the hippocampus, a brain structure important for both short- and long-term memory storage. Alzheimer's disease, the most common type of dementia, is associated with atrophy of the hippocampus.

Researchers have hypothesized that abnormal buildups of calcium, or calcifications, in the hippocampus may be related to vascular problems that could contribute to hippocampal atrophy and subsequent cognitive deterioration. However, published research on the association between hippocampal calcification and cognitive impairment is limited.

"We know that calcifications in the hippocampus are common, especially with increasing age," said the study's lead author, Esther J.M. de Brouwer, M.D, a geriatrician at the University Medical Center in Utrecht, the Netherlands. "However, we did not know if calcifications in the hippocampus related to cognitive function."

Advances in imaging have provided opportunities to explore the role of hippocampal calcifications in dementia.

The study led by Dr. de Brouwer and colleagues, included 1,991 patients, with an average age of 78 years, who had visited a memory clinic at a Dutch hospital between 2009 and 2015. The patients had a standard diagnostic workup including cognitive tests and brain CT scans. The researchers analyzed the CT scans for the presence and severity of hippocampal calcifications. The association between vascular risk factors like high blood pressure, diabetes and smoking, and hippocampal calcifications were evaluated. They also assessed the effects of calcifications on cognitive function.

Of the 1,991 patients, 380, (19.1%), had hippocampal calcifications. Older age, presence of diabetes and smoking habits were associated with an increased risk of hippocampal calcifications. While the study was not designed to conclusively determine if smoking and diabetes increase the risk of hippocampal calcifications, the results strongly suggest a link.

"We do think that smoking and diabetes are risk factors," Dr. de Brouwer said. "In a recent histopathology study, hippocampal calcifications were found to be a manifestation of vascular disease. It is well known that smoking and diabetes are risk factors for cardiovascular disease. It is, therefore, likely that smoking and diabetes are risk factors for hippocampal calcifications."

There was no link between the presence and severity of hippocampal calcifications and cognitive function; a surprising finding, according to Dr. de Brouwer, with several possible explanations.

"The hippocampus is made up of different layers, and it is possible that the calcifications did not damage the hippocampal structure that is important for memory storage," she said. "Another explanation could be the selection of our study participants, who all came from a memory clinic."

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