The Effects of Type 1 Diabetes on Cognitive Performance A meta-analysis

Department of Neurology, University Medical Center, Utrecht, the Netherlands.
Diabetes Care (Impact Factor: 8.42). 04/2005; 28(3):726-35. DOI: 10.2337/diacare.28.3.726
Source: PubMed


To investigate the exact nature and magnitude of cognitive impairments in patients with type 1 diabetes and the possible association with other disease variables, such as recurrent episodes of hypoglycemia and metabolic control.
MedLine and PsycLit search engines were used to identify studies on cognitive performance in patients with type 1 diabetes. Effect sizes (Cohen's d), which are the standardized differences between the experimental and the control group, were calculated. In the meta-analysis, a combined d value was calculated, expressing the magnitude of associations across studies.
A total of 33 studies were identified that met the inclusion criteria. Compared with nondiabetic control subjects, the type 1 diabetic group demonstrated a significantly lowered performance on the following cognitive domains: intelligence (d = -0.7), speed of information processing (d = -0.3), psychomotor efficiency (d = -0.6), visual (d = -0.4) and sustained attention (d = -0.3), cognitive flexibility (d = -0.5), and visual perception (d = -0.4). Lowered cognitive performance in diabetic patients appeared to be associated with the presence of microvascular complications but not with the occurrence of severe hypoglycemic episodes or with poor metabolic control.
In patients with type 1 diabetes, cognitive dysfunction is characterized by a slowing of mental speed and a diminished mental flexibility, whereas learning and memory are spared.The magnitude of the cognitive deficits is mild to moderate, but even mild forms of cognitive dysfunction might hamper everyday activities since they can be expected to present problems in more demanding situations.

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    • "Consequently, we aimed to explore neurofunctional activation in young T1D patients with normal intelligence and without diabetic complications versus healthy control participants during a visuospatial working memory task. If brain metabolism has been altered in these patients, as has been suggested [17] [32], then we would expect that the blood oxygen level-dependent (BOLD) fMRI activation response could reflect differences in cognitive processing between the two groups, especially considering that working memory is one of the cognitive domains [4] in these patients [3] [23] [33] that has most often been shown to be affected, and is most frequently explored. "
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    ABSTRACT: In recent years, increasing attention has been paid to the effects of Type 1 Diabetes (T1D) on cognitive functions. T1D onset usually occurs during childhood, so it is possible that the brain could be affected during neurodevelopment. We selected young patients of normal intelligence with T1D onset during neurodevelopment, no complications from diabetes, and adequate glycemic control. The purpose of this study was to compare the neural BOLD activation pattern in a group of patients with T1D versus healthy control subjects while performing a visuospatial working memory task. Sixteen patients and 16 matched healthy control subjects participated. There was no significant statistical difference in behavioral performance between the groups, but, in accordance with our hypothesis, results showed distinct brain activation patterns. Control subjects presented the expected activations related to the task, whereas the patients had greater activation in the prefrontal inferior cortex, basal ganglia, posterior cerebellum, and substantia nigra. These different patterns could be due to compensation mechanisms that allow them to maintain a behavioral performance similar to that of control subjects.
    Journal of Diabetes Research 07/2015; 2015(1):1-9. DOI:10.1155/2015/703512 · 2.16 Impact Factor
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    • "Hyperglycemia is a characteristic in both T1DM and T2DM. Numerous studies have demonstrated a close relationship between glucose intolerance and cognitive decrements and dementia [24] [69] [70]. It has been shown that people with poor glycemic control, with glycosylated hemoglobin (HbA1c) higher than 7.0%, have a 4-fold higher risk of developing cognitive impairment [71]. "
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    International Journal of Endocrinology 06/2015; 2015. DOI:10.1155/2015/810439 · 1.95 Impact Factor
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    • "For example, spatial learning and memory are impaired in the water maze during diabetes [1] [2]. Diabetic children and adults exhibit reduced psychomotor efficiency, cognitive flexibility, and rapid information-processing [3]. Passive avoidance learning (PAL) and memory deficits also occur in streptozocin (STZ) induced diabetic rats [4]. "
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    ABSTRACT: Diabetes mellitus is a common metabolic disorder that is associated with many complications such as learning and memory deficits. Rubus fruticosus (blackberry) has been extensively used in herbal medicine. In this study we evaluated the effect of R. fruticosus (RF) extract against memory dysfunction on streptozocin (STZ) induced diabetic neuropathy. Diabetes was induced by a single injection of STZ (60 mg/kg i.p). Treatments were begun at the onset of hyperglycemia, followed by treatment with the RF extract (100, 200 and 400 mg/kg p.o) for 4 weeks. Cognitive functions were evaluated using passive avoidance learning (PAL) task. Retention test was carried out 24 h after training. At the end of experiment, animals were weighted and blood samples were taken for plasma glucose measurement. Diabetes caused impairment in acquisition and retrieval processes of PAL and memory in rats. RF treatment improved learning and memory in non-diabetic rats and reversed learning and memory deficits in diabetic rats. RF administration also partially improved the body weight loss and hyperglycemia of diabetics. These results show that RF administration to rats for 30 days from onset of diabetes alleviated the negative influence of diabetes on learning and memory.
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