Published: Dec 2, 2014
By Kristina Fiore, Staff Writer, MedPage Today
Having type 2 diabetes in middle age was tied to cognitive decline later in life, researchers found.
Having type 2 diabetes in middle age was tied to cognitive decline later in life, researchers found.
In an analysis of data from the ARIC study, patients who had diabetes when they entered the study had a 19% greater decline in adjusted global cognitive Z-scores over 20 years than those without the condition, reported Elizabeth Selvin, PhD, MPH, of Johns Hopkins Bloomberg School of Public Health, and colleaguesonline in the Annals of Internal Medicine.
“Diabetes and glucose control are potentially modifiable and may offer an important opportunity for the prevention of cognitive decline, thus delaying progression to dementia,” Selvin said. “At the population level, delaying the onset of dementia by even a couple of years could reduce its prevalence by more than 20% over the next 30 years.”
Selvin and colleagues looked at data on 13,351 adults who were enrolled in theAtherosclerosis Risk in Communities (ARIC) study between 1990 and 1992. Participants’ baseline ages were between 48 and 67.
The researchers used three neuropsychological tests to assess cognitive function during the study:
- Delayed Word Recall Test (DWRT)
- Digit Symbol Substitution Test (DSST)
- Word Fluency Test (WFT)
They found that having diabetes in midlife was associated with significantly greater declines in DSST and WFT, but not DWRT.
Both the DSST and the WFT reflect impairments in the domains of processing speed and executive function, suggesting that the association between diabetes and cognitive function “may involve the subcortical microvasculature that damages white matter pathways or subcortical gray matter in other ways.”
When looking at the tests results together, the average decline in global cognitive Z-score over 20 years was far greater in those who had diabetes — 0.92 versus 0.78 — which amounted to a 19% greater decline in cognitive function for those with diabetes in midlife.
Cognitive decline was also worse for those who had prediabetes — an HbA1c of 5.7% to 6.4% — at baseline, with a difference of 0.07 points in average cognitive Z-scores over the 20 years of the study (P=0.005).
Longer duration of diabetes was also associated with greater late-life cognitive decline (P<0.001 for trend), Selvin and colleagues added.
They concluded that diabetes prevention and glucose control in midlife may protect against cognitive decline down the road.
ARIC is supported by the National Heart, Lung, and Blood Institute (NHLBI).
Selvin was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases. Some co-authors were supported by grants from the NHLBI and the National Institute on Aging.