Cumulative HbA1c levels above 9% linked to greater dementia risk

25th April 2023

HbA1c levels in type 2 diabetics remaining above 9% for extended periods of time poses a risk of developing dementia

Type 2 diabetes increases the risk for developing dementia. Both elevated HbA1c levels and diabetic complications also linked to an increased dementia risk. Moreover, intensive glycaemic control does not seem to reduce cognitive decline. But how long-term glycaemic control affects the risk of dementia is uncertain and was the subject of the current study.

Using a large US healthcare database, researchers looked at type 2 diabetics older than 50 with HbA1c levels recorded over time. Researchers categorised HbA1c measurements as < 6%; 6% to < 7%; 7% to < 8%, 8% to < 9%, 9% to < 10% and 10% or more. They also identified those diagnosed with dementia during follow-up.

HbA1c levels and development of dementia

There were 253,211 eligible participants with a mean age of 61.5 years. The participants were followed for a mean of 5.9 years. During this time, participants with the majority (i.e., > 50%) of HbA1c measurements between 9 and 10%, had an increased the risk of dementia (hazard ratio, HR = 1.31, 95% CI 1.15 – 1.51). Similarly, with most measurements of 10% or above, the risk was also significantly higher (HR = 1.74, 95% CI 1.62 – 1.86).

In contrast, among participants with more than 50% of HbA1c measurements that were less than 6%, the dementia risk was lower (HR = 0.92, 95% CI 0.88 – 0.97). This also held true for HbA1c levels of 6 to 7% and between 7 and 8%. Thus in type 2 diabetics, keeping cumulative HbA1c levels below 8% was associated with a lower risk for developing dementia. The researchers called for further research to determine if these associations were causal.

Citation
Moran C et al. Glycemic Control Over Multiple Decades and Dementia Risk in People With Type 2 Diabetes. JAMA Neurol 2023

Dementia risk reduced by higher and more intense daily steps

12th September 2022

Dementia risk can be reduced by half among adults who undertake nearly 10,000 daily steps especially if they increase the intensity of steps

Adults who take just short of 10,000 steps/day, particularly if those steps are more intense, have a reduced dementia risk according to a study by a team from Denmark and Australia.

Dementia describes a syndrome in which there is a deterioration in cognitive function beyond what might be expected from the usual consequences of biological ageing and which according to the world health organisation, globally, affects around 55 million people.

In a 2020 report published in The Lancet, it was noted how there is a growing body of evidence that supports the nine potentially modifiable risk factors for dementia, one of which is physical inactivity. The authors recommended keeping cognitively, physically and socially active in midlife and later life although little evidence exists for any single specific activity protecting against dementia.

In an analysis of 15 cohort studies with over 47,000 adults, researchers concluded that taking more steps per day was associated with a progressively lower risk of all-cause mortality. Despite this benefit, evidence also suggests that step cadence, i.e., the number of steps per minute, or step intensity does not appear to be significantly associated with mortality.

With a lack of supportive evidence for the value of greater physical activity in reducing the risk of developing dementia, in the present study, researchers examined the association between daily step count as well as intensity and dementia risk.

They used data held within the UK Biobank where a cohort of over 100,000 individuals had agreed to wear an accelerometer on their dominant wrist 24 hours a day and 7 days a week, to measure physical activity. All were free of dementia at the start and as well as recording total daily steps, the researchers also examined step cadence.

This was divided into incidental steps, defined as fewer than 40 steps/minute, such as walking between rooms at home, purposeful steps, which > 40 steps/minute, for instance, while exercising and finally, peak 30-minute cadence, which was the average steps/minute recorded for the 30 highest, but not necessarily consecutive, minutes in a day.

The researchers estimated the optimal dose of steps, where the maximum significant dementia risk reduction was observed and the minimal dose, which was defined as the number of steps at which the risk reduction was 50% of the maximum. In regression models, adjustments were made for age, sex, lifestyle and co-morbidities.

Dementia risk and daily steps

The overall cohort included 78,430 individuals with a mean age of 61.1 years (55.3% female) and who were followed for a median of 6.9 years. During the follow-up period, 866 participants developed dementia at a mean age of 68.3 years.

The optimal dose of daily steps was 9826 and this led to a 51% lower risk of developing dementia (hazard ratio, HR = 0.49, 95% CI 0.39 – 0.62) and the minimal dose of 3826 steps/day (HR = 0.75, 95% CI 0.67 – 0.83).

For peak 30-minute cadence, the optimal dose was 112 steps/minute (HR = 0.38, 95% CI 0.24 – 0.60) and 6315 for purposeful steps.

The authors concluded that taking more daily steps was associated with a reduced dementia risk with the optimal dose just short of 10,000 steps/day and also that step intensity led to stronger associations. They suggested that future guidelines for dementia prevention should promote step-based recommendations.

Citation
del Pozo Cruz B et al. Association of Daily Step Count and Intensity With Incident Dementia in 78 430 Adults Living in the UK JAMA Neurol 2022