Elderly patients with type 2 diabetes had diminished frontal brain activity on functional magnetic resonance imaging that correlated with deficits in working memory and executive function, investigators have reported. The results were published online Nov. 17.
“To our knowledge, this study is the first to detect the specific brain mechanisms related to diabetes-induced working memory dysfunction,” wrote Dr. Yaojing Chen of Beijing Normal University, China.
Patients with diabetes also exhibited varying frontal brain deficits depending on the difficulty of the working memory tasks they were asked to perform. The left inferior frontal gyrus had reduced brain activation during easier tasks, while the middle frontal gyrus and the superior frontal gyrus were affected during more difficult tasks (Diabetes Care 2014 Nov. 17 [doi: 10.2337/dc14-1683]).
Type 2 diabetes is known to expedite brain aging and increase the risk of Alzheimer’s disease. Affected patients can develop deficits in executive functioning, attention, memory, and visuospatial abilities, the researchers noted. To visualize the specific structures affected, the researchers performed functional magnetic resonance imaging (fMRI) of 67 patients from the Beijing Aging Brain Rejuvenation Initiative, a longitudinal study of aging and cognitive impairment in the urban elderly population of Beijing.
Patients in the study had no history of dementia or psychiatric illness, coronary artery disease, nephritis, cancer, or gastrointestinal disease.
Compared with 37 controls, the patients with diabetes performed significantly worse on several working memory tasks, including the backward digit span, the digit span, and the Stroop Color and Word Test, which is an executive function task, the researchers reported.
Patients with diabetes also had less fMRI activation in several frontal brain areas, including the right superior frontal gyrus, the bilateral medial frontal gyrus, and the inferior frontal gyrus. Furthermore, the diabetes group had lower fMRI activation of the left inferior frontal gyrus (Brodmann area 13) in the 1-back versus 0-back (working memory) condition, and had less activation of the left middle frontal gyrus and the superior frontal gyrus in the 2-back versus 0-back comparison, they added. “These findings indicate that with increasing task difficulty, additional frontal brain regions might have been recruited to play compensatory roles to complete the harder task,” they said.
Larger longitudinal studies would be needed to confirm the findings and explore their potential for predicting early cognitive changes in patients with type 2 diabetes, they noted.
The research was funded by the Beijing New Medical Discipline Based Group, the Natural Science Foundation of China, the Institute of Basic Research in Clinical Medicine, the China Academy of Chinese Medical Sciences, and the program for New Century Excellent Talents in University. The researchers declared no conflicts of interest.
cenews@frontlinemedcom.com
