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 Researchers followed 705 older adults without dementia for an
average of 4.6 years. At the start, participants were between 55 and
90 years old, with an average age around 70, and 348 of them had
diabetes.
In people with diabetes, verbal fluency declined slightly over the
course of the study, while it improved slightly in participants
without diabetes, researchers report in Diabetologia.
Diabetes develops when the body can't properly use insulin to
convert blood sugar into energy and the condition is associated with
obesity and aging. While diabetes has long been linked to cognitive
decline and dementia, research to date hasn't offered a clear reason
for this connection.
Three times during the study, participants had brain scans to look
for any signs of atrophy - tissue shrinkage - and they took
cognitive tests involving verbal skills.
Although people with diabetes already had more brain atrophy at the
start, there was no difference between those with and without
diabetes in the rate of brain shrinkage during the study. Atrophy
also didn't appear to explain the link between diabetes and
cognitive decline.
Still, the results suggest that brain changes associated with
diabetes may begin earlier than previously thought, perhaps in
middle age, said lead author Michele Callisaya of the University of
Tasmania in Hobart, Australia.
For patients, this means it would be a mistake to put off thinking
about brain health until they're older or experiencing symptoms of
cognitive decline, Callisaya said by email.
"Recommendations for good brain health include physical activity,
following a healthy diet, maintaining a healthy weight, checking
blood pressure and cholesterol, mentally challenging the brain and
enjoying social activities," Callisaya said.
The diabetics in the study were a bit younger, 68 years old on
average, compared with an average of 72 for the participants without
diabetes.
Researchers accounted for age, sex, education and risk factors like
current or former smoking, obesity and elevated blood pressure or
cholesterol.
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One limitation of the study is that the diabetics had relatively
well-controlled blood sugar, and it's possible that the connection
between diabetes and changes in the brain might be more apparent in
patients with higher blood sugar, the study authors note.
"There isn't evidence that keeping blood (sugar) under control
directly improves cognition or lessens cognitive decline," said Dr.
Rebecca Gottesman of Johns Hopkins University in Baltimore,
Maryland. "But it is likely that long-term control of blood sugar
has benefits for the brain," Gottesman, who wasn't involved in the
study, said by email.
Another limitation is that the study may have been too brief to
detect meaningful differences in cognition and brain volume between
people with and without diabetes because these changes can happen
slowly.
The diabetics might have had reduced brain reserve, or the ability
to withstand damage, when they joined the study, said Jill Morris a
researcher at the University of Kansas Alzheimer's Disease Center in
Fairway.
The good news is there's plenty that people can do to help keep
their mind sharp, Morris said in an email.
"Keep your body and mind active," she advised.
"Diet and exercise are key components of brain health and can
simultaneously impact blood sugar levels, insulin resistance, and
cerebrovascular disease," Morris added. "These factors are linked to
important cognitive and brain-related outcomes in a variety of
populations, and are especially important in individuals with type 2
diabetes."
SOURCE: https://bit.ly/2C73WrG Diabetologia, online December 13,
2018.
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