ReviewUpdate on cognitive decline and dementia in elderly patients with diabetes
Introduction
In their everyday clinical practice, endocrinologists are facing a growing number of diabetic patients manifesting signs of cognitive decline and even full-blown dementia. The association is not surprising as these conditions share common features that are highly prevalent in the elderly population. In France, the prevalence of diagnosed diabetes increases with age to a maximum of 19.7% in men and 14.2% in women aged 75–79 years [1], while data from the PAQUID study suggest a 17.8% prevalence rate of dementia in people aged > 75 years [2]. The elevated frequency of cognitive dysfunction in elderly diabetics has been found in a majority of cross-sectional studies. Recently, 29% of the elderly patients with type 2 diabetes (T2D) included in the French GERODIAB study had impaired cognition at baseline [3]. Thus, cognitive dysfunction is a frequent clinical problem that requires early identification and integration into the management of diabetes in the elderly.
The purpose of the present report is to provide an update of the most significant findings concerning cognitive deficits and dementia in elderly patients with T2D.
Section snippets
Diabetes increases the risk of cognitive decline and dementia
Diabetes itself has been recognized as an independent risk factor for the development of cognitive impairment in large prospective population-based studies with follow-up durations of up to 18 years [4], [5], [6], [7], [8], [9]. In one extensive review [4], the annual rate of global cognitive decline, as measured by changes in Mini-Mental State Evaluation (MMSE) score [10], was found to be up to 1.5 times greater in diabetics than in non-diabetics. Some studies confirmed a greater risk of global
Cognitive decline is related to poor glycaemic control
Many studies have demonstrated a link between poor glucose control and deteriorated cognitive function in diabetes. Higher haemoglobin HbA1c levels were consistently associated with lower scores on cognitive testing [16], [17] and greater decline in cognition over time [18] in older adults with T2D. In contrast, cognitive benefits for working memory were achieved with improved glucose control in a short-term study of older diabetics [19]. More recently, dementia-free 55- to 80-year-old patients
Hypoglycaemia is important in diabetics with poor cognitive function
The incidence of hypoglycaemic episodes is important, but is probably underrecognized by diabetic patients as they advance in age: 33.6% of patients aged ≥ 70 years reported at least one hypoglycaemic episode; 3.3% have declared severe hypoglycaemia; and 0.6% have fallen into coma in the 6 months prior to inclusion in the GERODIAB study [3]. The link between the occurrence of hypoglycaemia and altered cognitive function has received much attention in older people with diabetes.
Cognitive impairment contributes to negative health outcomes
Cognitive deficits, in addition to other complications of late-life diabetes, can compromise patients’ daily activities and become potential barriers to self-care in diabetic patients. Cognitive fragility may also have social and economic consequences for such patients, and may contribute to significantly altered quality of life in this population.
Specific treatment strategies are required
As they advance in age, diabetic patients are more likely to develop comorbidities and functional impairment; they also usually have a higher prevalence of depression, and an increased risk of cognitive decline and dementia. For these reasons, a patient-centred approach that takes into account the presence of associated diseases and geriatric conditions, and the patient's needs and preferences, is a core principle underlying healthcare for elderly patients. This approach has been systematically
Conclusion
People with diabetes have an increased risk of cognitive dysfunction and dementia. Some researchers have even suggested that cognitive impairment and dementia be included in the list of late complications of diabetes. Diabetic patients with cognitive deficits are also at greater risk of presenting with severe hypoglycaemia. Because cognitive impairment in elderly diabetic patients can have a considerable impact on their daily life activities, functional autonomy and ability to manage
Disclosure of interest
Lyse Bordier and Bernard Bauduceau have received lecture fees from pharmaceutical companies that market drugs for the treatment of diabetes, namely, Bristol-Myers Squibb, Eli Lilly, MSD, Novo Nordisk and Sanofi-Aventis.
Jean Doucet is coordinator of the GERODIAB study. The study is being carried out with a grant from Novo Nordisk and Merck Serono, a research grant from the Société Francophone du Diabète (French-speaking Diabetes Society) and a national Programme Hospitalier de Recherche Clinique
Acknowledgments
The authors thank Catherine Soubrouillard (Eltium), who provided medical writing services on behalf of Lilly France.
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