NEW YORK—Cerebral blood flow (CBF) in healthy older people predicts cognitive function four years later, according to results from an arterial-spin-labeling perfusion-MRI study.
“Specifically, we found that brain blood flow measured at the present time can predict a person’s general cognitive ability and, most significantly, memory function,” Dr. Hanzhang Lu from Johns Hopkins University School of Medicine, in Baltimore, Maryland, told Reuters Health by email. “Across different brain regions we studied, we found that the frontal lobe is the most important in determining future cognitive function.”
Cognitive abilities decline with age starting from the third decade of life, with the greatest effects on fluid cognition (related to performing tasks). Neuroimaging studies have shown that both brain structure and function deteriorate with age. It remains to be seen, however, whether a particular biomarker can predict future cognitive performance.
Dr. Lu’s team examined the relationship between CBF and cognitive function among 309 participants aged 20 to 89 years in the Dallas Lifespan Brain Study.
At the year four follow-up, all participants remained free of mild cognitive impairment or dementia, but there were age-related decreases in CBF and cognition. Participants who were older at baseline experienced faster declines in cognitive function, compared with younger subjects.
Among participants who were 54 years or older at baseline, higher whole-brain CBF at baseline significantly predicted better fluid cognition (a construct of processing speed, working memory, reasoning, and episodic memory) four years later, the team reports in the Journal of Magnetic Residence Imaging, online January 2.
Across the entire group, however, whole-brain CBF did not significantly predict fluid cognition, but it did predict follow-up episodic memory in older individuals and in the entire cohort.
Frontal lobe CBF best predicted follow-up fluid cognition, episodic memory, and reasoning in the older group, whereas frontal lobe CBF was only predictive of episodic memory in the entire cohort.
In contrast, baseline CBF in the occipital, parietal and temporal lobes was not predictive of any cognitive domains at follow-up.
Changes in reasoning ability between baseline and follow-up were dependent on parietal CBF in the older group and whole-brain CBF in the entire group, but there were no other associations between lobar CBF and changes in cognitive functions.
“The significance of these findings is that physicians can use some of these measures, including blood flow but also other complementary measures such as amyloid imaging, to identify which of their patients have higher risks for cognitive decline,” Dr. Lu said.
“They can then determine the best intervention or treatment strategies for each patient. The physicians can also use these measures to select the best candidates for novel therapies such as those undergoing clinical trials,” he said.