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Dementia onset, mortality occurred earlier in diabetes
Patients with diabetes are at risk for early-onset dementia and mortality, especially among older age groups, according to researchers in Australia.
Although the epidemiology surrounding the association between diabetes and dementia remains fairly uncertain, researchers wrote that the effect of diabetes on dementia projections based on their study is likely to worsen, given the incidence and prevalence of type 2 diabetes and obesity.
Research fellow Renate R. Zilkens, MPH, of Curtin University, and colleagues conducted a retrospective population study utilizing Western Australian hospital inpatient, mental health outpatient and death records to compare the age at index dementia record (proxy for onset age) and survival outcomes among dementia patients with and without pre-existing diabetes (n=25,006; diabetes, 17.3%).
According to the researchers, dementia onset occurred at an average of 2.2 years earlier and death 2.6 years earlier in patients with diabetes compared with patients without diabetes (P<.0001). Additionally, the age-specific mortality rates increased in patients with diabetes, they wrote.
“The public health significance of a 2.2-year age difference seems modest, yet it has been estimated that an intervention able to delay the onset of Alzheimer’s disease by 2 years would reduce the projected quadrupling of Alzheimer’s disease prevalence by year 2050 by over 20%,” the researchers wrote.
Upon further analyses, the death rate was increased with a long duration of diabetes, particularly in early-onset dementia. However, in dementia diagnosed before age 65 years, patients with at least a 15-year history of diabetes died nearly twice as fast vs. those without diabetes (HR=1.9; 95% CI, 1.3-2.9), according to data.
Moreover, these death rates were significantly higher when associated with a long duration of diabetes in the 65- to 74-year-old age group (HR=1.5; 95% CI, 1.1-1.19) and 75- to 84-year-old age group (HR=1.4; 95% CI, 1.2-1.6).
“These findings, amplified in early-onset dementia and by long-duration diabetes, have major implications for estimating the future dementia disease burden due to diabetes as well as clinical implications for affected patients and their families,” Zilkens and colleagues wrote.
Disclosure: The researchers report no relevant financial disclosures.
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Kelly T. Dineley
Larry A. Denner
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The observations in this report have a staggering impact, not only for the present but particularly for the future. The authors performed a retrospective study using proportional hazards models to show that early-age onset of diabetes results in an earlier-onset of dementia with an overall decreased survival. Insulin resistance induces a prediabetes state and increases the risk for type 2 diabetes. Both insulin resistance and type 2 diabetes are increasing in frequency and the age of diagnosis continues to decrease. Thus, the implications of the Zilkens et al. study are that with the continuing decline in the age of onset of diabetes and related conditions, there will be more dementia patients at ever younger ages. With the skyrocketing incidence of Alzheimer’s disease due to dementia (AD), and the emerging relationship between insulin resistance and AD, dementia due to AD will also increase in frequency at younger ages. These studies clearly emphasize the importance of public awareness of the risks of diabetes and the diabetes-related metabolic syndrome as risk factors for dementia and AD. By emphasizing early detection of insulin abnormalities and control of diabetes, it may be possible to diminish the impact of the associated risk for dementia and AD.
- Kelly Dineley, PhD
- Associate professor in the department of neurology
University of Texas Medical Branch in Galveston - Larry Denner PhD
- Professor in the division of endocrinology, department of internal medicine
Associate director of research, Nelda C. and H.J. Lutcher Stark Diabetes Center
Director of the Miriam and Emmett McCoy Diabetes Mass Spectrometry Laboratory
University of Texas Medical Branch in Galveston
- Disclosures: Denner and Dineley report no relevant financial disclosures.
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One issue that arises when we talk about diabetes and dementia is the precise type of dementia: was it really Alzheimer’s disease (a pathologic diagnosis), or was there another cause of the dementia? The researchers of this paper were very responsible, carefully noting the way they obtained diagnoses and noting the imprecise nature of classification.
This study does add validation to prior research reporting earlier onset dementia in patients with (long-standing) diabetes. It may well still be that the dementia related to diabetes is more from a vascular etiology, given what we know about diabetes effect on vasculature.
There has been a lot in the news recently and reports in literature for a long time that there may be an association between dementia and diabetes, and that the brain is essentially one of the end-organs impacted by diabetes. If there are high levels of blood glucose, that aren’t controlled, it impacts the vasculature or the brain as it does other areas of the body. This study indicates other potential negative sequelae of diabetes, and that diabetes may hasten the clinical onset of dementia (in patients who otherwise would show dementia later). This paper suggests an interesting association in a well-done, large scale study.