Diabetes is a chronic disease characterized by abnormally high levels of sugar in the blood. Type 1 and Type 2 diabetes result from the body's inability to make or use insulin. Without insulin, blood glucose levels rise too high, causing a range of potentially life-threatening symptoms that can affect vital organs. Diabetes also has a number of demonstrated effects on the brain, cognitive performance and memory.
Mild Cognitive Impairment
Mild cognitive impairment (MCI) is considered a transitional state between normal brain functioning and aging and Alzheimer's disease or other dementias. A study published in the August 2008 issue of Archives of Neurology determined that people with earlier onset diabetes, more severe diabetes and those with a longer duration of the condition are more likely to develop symptoms of mild cognitive impairment that include mild forgetfulness, language, attention or learning problems. Though researchers aren't certain what causes these impairments, they suspect it may be related to the body's impaired insulin response and its effects on glucose uptake in the brain, to diabetes' damaging effects on blood vessels that may cut off blood supply to small blood vessels and neurons in the brain, or to diabetes' effects on deposition of amyloid proteins that cause plaques on the brain.
A review published in the March 2005 issue of Diabetes Care finds that people with Type 1 diabetes also demonstrate mild cognitive impairment characterized by decreased mental speed and worsening mental flexibility. The study reports that learning and memory are typically less affected. Although these deficits don't hamper everyday activities, they may create problems in more demanding activities and situations.
Food-related Memory Loss
Adults with Type 2 diabetes may demonstrate declines in memory immediately following ingestion of a high-fat meal. A study in the July 2008 issue of Nutrition Research finds that adults who consume antioxidant vitamins along with fatty meals can offset these cognitive impairments. Researchers Dr. Carol Greenwood and Dr. M.H. Chui note that Type 2 diabetes is associated with chronic oxidative stress, which may be a cause of cognitive decline and Alzheimer's disease. Certain unhealthy foods can trigger elevations of free radicals (molecules that damage brain tissue), causing memory dysfunction for up to three hours after ingestion.
Dementia
Uncontrolled diabetes increases the risk for developing dementia. A study published in the April 15, 2009, issue of the Journal of the American Medical Association reports that adults with a history of hypoglycemic episodes that are serious enough to require emergency care or admission to a hospital are at increased risk of developing dementia. As a risk factor for stroke, diabetes also increases the risk of dementia. Another study published in the January 2009 issue of Neuropsychology found that those with diabetes may be particularly likely to experience deficiencies in executive functioning (goal-directed behaviors such as initiating and stopping actions, planning, monitoring and changing behavior) and processing speed. Further, these deficits were found to develop early in the disease process and to persist long-term.
References
- "Archives of Neurology;" Association of Duration and Severity of Diabetes Mellitus With Mild Cognitive Impairment; RO Roberts et al.; August 2008
- "Diabetes Care;" The Effects of Type 1 Diabetes on Cognitive Performance: A Meta-Analysis; AMA Brands et al.; March 2005
- "Nutrition Research;" Antioxidant vitamins reduce acute meal-induced memory deficits in adults with type 2 diabetes; MH Chui and CE Greenwood; July 2008
