Just when you thought you knew about every complication of diabetes, we read about another, and here we share with you some information that you will want to discuss with your physician or your loved one with diabetes. Although we have brought you research about cognitive decline and diabetes before, this article spells out the research in an excellent overview.
Diabetes and Cognitive Decline or Dementia:
There have been studies on this subject since the 1980’s. Some speculate the cause to be chronic hyperglycemia and the production of advanced glycated end products that may damage vascular tissue and endothelial function, DNA, and mitochondria in the brain, and increase free radicals, inflammatory responses, and amyloid deposition.
It is also thought that chronic hyperglycemia may influence cerebral blood flow, neurotransmitter function, or nutrient delivery to the brain. In addition, diabetes may influence cognitive function by leading to cardiovascular events, transient ischemic attacks, and strokes.
Repeated hypoglycemic events and related metabolic and vascular disruption might influence long-term cognitive function. There is also the thought that diabetes may be a marker of other factors like insulin resistance and hypertension which may make us more susceptible to both diabetes and Alzheimer’s disease.
The article presents the data from several large prospective studies that have shown an association of diabetes to cognitive decline and dementia during the last 5 years. Two of these found a 60-100% greater risk of cognitive decline among people with diabetes when compared to those without diabetes.
Recent studies have also found a 50-200% greater risk for overall dementia and Alzheimer’s disease, while others; however, have shown no association with the later. The bad news is that there is no research data to determine the specific mechanisms underlying this association. It is also unknown whether aspects of metabolic and cardiovascular risk control among people with diabetes plays any role in increasing the risk of cognitive impairment and decline.
Association between Diabetes and Physical Disability or the Ability to Function
Women with diabetes walked slower, with worse balance and a 58% higher likelihood of falling than did those without diabetes. More recently completed studies reiterate these findings.
The mechanisms that might explain these findings include high BMI and CHD. In women these accounted for 52% of their increased risk. Among men, CHD and stroke were the most important explanatory factors, explaining 25% and 21% of the excess disability risk.
In Study of Osteoporotic Fractures, age, CHD, arthritis, physical inactivity, BMI, and visual impairment were key predictors of disability among women with diabetes. The Women’s Health and Aging study found peripheral nerve dysfunction, peripheral arterial disease, and depression were main predictors of disabilities. At least 4 large studies have found an increased risk of falling among older adults with type 2 diabetes. The incidence of fractures resulting from these indicates that women with diabetes may be at particularly increased risk of hip and foot fractures.
Interventions to Reduce Cognitive and Functional Decline
As a result of extensive studies over the past decade, we know that aggressive treatment of hyperglycemia, blood pressure, and lipids; aspirin use; smoking cessation; and regular screenings for foot, eye and kidney problems may prevent and delay complications of diabetes.
Some of these and other interventions might also influence the risk of age-related cognitive and physical disabilities. The bad thing here is that most studies are done on middle-aged populations and almost none examine the effect of interventions on cognitive or functional decline.
Management of glycemia and blood pressure could conceivably ameliorate cognitive decline in diabetics. Two short term studies suggested that this was true over a 3-6 month period of tight control.
Another study found that people who had intensive inpatient management had improved concentration and psychomotor function compared to people who received regular at-home care. So, although studies point in this direction, glycemic control in older populations remains unclear because of lack of research.
Several studies have examined the effects of antihypertensive treatment on cognitive function, examining cardiovascular disease outcomes. Two of these studies found no effect of antihypertensive treatment on the rate of cognitive decline, but another found a 50% reduction in the incidence of dementia among hypertensive adults aged 60 or older after 2 years of treatment.
In another study, those treated with antihypertensives showed a 55% lower incidence of dementia. The treatment group also had a lower rate of disability measured by difficulty carrying out daily activities. Neither of these studies was done of people primarily with diabetes.
Several potential interventions could reduce the risk of physical disability, but none have been tested in research on older diabetic people. In recent observational studies of diabetic adults, physical inactivity, obesity, depression, CHD, lower-extremity disease, and arthritis were identified as factors associated with physical disability.
Structured exercise programs involving walking, and strength and balance training have been associated with improved functional status and reduced incidence of disability among older adults. Weight loss has also been associated with improved physical functioning in obese people, but it is unclear whether weight loss is likely to improve long-term outcomes among older people with diabetes.
Primary Case Management
Although the clinical goals may be the same for people with diabetes no matter their age, several factors make the care of older patients complex. The functional status of older people is more heterogeneous than that of younger people because the older population ranges from people with newly diagnosed diabetes to those with poorly controlled diabetes. Some people have few complications while other have many diabetes related complications.
Similarly, life expectations vary considerably, so intervention may have different value for different patients depending on their anticipated effect on quality of life. For frail older adults with diabetes who have a short life expectancy, substantial morbidity, and/or significant difficulty adhering to treatment plans, aggressive targets for blood pressure, lipids, or glucose levels may not be appropriate or even attainable.
Aggressive management of these conditions may not provide the same benefits observed in younger people and can instead bring harm such as hypoglycemia or hypotension. The goal may be in these cases, to enhance quality of life with less aggressive targets at reducing or managing symptoms.
Polypharmacy is more common in the elderly because of the need to control glycemia, hyperlipidemia, hypertension, and associated medical conditions. But, prescribing many medications can affect cognitive ability, physical functioning, and depression through drug-drug or drug-disease interactions.
The use of medications, especially those with sedating effects, is a risk factor for falls and cognitive impairment. Other medications have been associated with urinary incontinence, depression and failure to thrive.
It is therefore important for health care providers to carefully review medications and have a clear rationale why each is prescribed. It is also important to consider costs and dosing schedules. For the elderly once a day medications are more compliant friendly. It is mandatory to discuss the benefits and potential side effects of each medication with the patient and family members or caregivers.
Depression is more common among people with diabetes than those without diabetes and may be a key mediator of the association between diabetes and cognitive decline. Depression is also likely to impede diabetes self-management and to increase the risk for diabetes-related morbidity and death.
Older adults have high rates of under-diagnosis and undertreatment of their depression. Studies have shown that pharmacological or psychological treatment of older adults is effective in reducing depressive symptoms.
There is a great deal of evidence that the incidence of physical decline and related geriatric syndromes among older diabetic adults indicates the need for focused attention on clinical and public health approaches to reduce the burden.
Specific guidelines for the management of older people with diabetes may help reduce some of the functional decline that has been documented. The author suggests office-based and system-based approaches to improve long-term functioning of older people. These approaches include screening for dementia, impaired physical functioning, depression, and frailty to help focus treatment approaches, identify preventable causes, and better organize caregivers.
Broader system-based approaches include case management, home geriatric assessment, and disease management programs. More research is needed into the effectiveness of varied approaches so that they can be prioritized and implemented in the form of public health policy.
In the mean time, as a caregiver, please take this information to the health care team, and problem solve, to make sure your loved one has the best of medical care to prolong self-sufficiency and health.