Recognizing And Addressing Cognitive Impairment In Patients With Diabetes

With the myriad of systemic complications associated with diabetes mellitus, treating patients with diabetes can be a monumental undertaking for both the patient and physician alike. Cognitive impairment is a common sequela associated with diabetes mellitus that is rarely cited, much less addressed, in the orthopedic literature, but can certainly perpetuate complications and further impede the successful treatment of the patient with diabetes. Tasks ranging from adherence to weightbearing status to understanding the severity and gravity of complications are undeniably blunted in the diabetic population with cognitive impairment.

Given this hindrance, it is not surprising that patients with diabetes succumb to higher rates of recidivistic pathology. However, understanding and addressing this aspect of the diabetic population may have the potential to improve outcomes and provide for an enhanced quality of life.

Mild cognitive impairment in patients with diabetes is an impairment of learning, memory, perception and central executive function.¹ The pathophysiology of cognitive impairment in diabetes mellitus is uncertain, but the condition has been frequently linked to patients with diabetes. In a study looking at cognitive function and increased frailty in 2,210 patients without diabetes in comparison to 486 patients with type 2 diabetes, the prevalence of cognitive impairment and/or increased frailty was 19.8 percent and 11.5 percent in those with type 2 diabetes with cognitive dysfunction alone.²

Researchers have also identified mild cognitive impairment as a precursor to Alzheimer’s disease and dementia, and subsequently cited diabetes as a risk factor to Alzheimer’s disease.³ Cognitive dysfunction can arise in patients with both type 1 and type 2 diabetes, but those with type 2 diabetes are more likely to perform poorly on tasks related to memory and learning in comparison to those with type 1 diabetes, according to McCrimmon and colleagues.⁴ In a disease that requires vigilant monitoring and assessment, any cognitive impairment has the potential to lead to complications.

While there are no established criteria in detecting cognitive dysfunction within patients with diabetes, other than specific task-oriented parameters like memory testing, there are identifiable risk factors. One study noted patients at least 65 years old with diabetes had increased episodic memory complications in comparison with their younger counterparts.⁵ Moreover, elderly patients with a lower extremity amputation were four times more likely to have decreased cognitive function, especially in relation to episodic memory impairment. A review of longitudinal studies assessing cognitive decline in patients with type 2 diabetes, 60 to 80 years old, found increased cognitive decline up to 1.5 times the rate in the control group.⁶

Smoking and other comorbidities are also risk factors for cognitive dysfunction. Decreased semantic memory and perceptual speed were strongly associated in one study with smoking and vascular disease in patients with type 2 diabetes.⁷ The presence of comorbidities such as obesity, depression, hypertension and vascular disease may also be contributory to cognitive decline in patients with diabetes.⁸

Perhaps counterintuitively, hypoglycemia (HbA1c <7%) has also been associated with decreased processing speed as well as decreased visual reaction time in patients with diabetes.^5,9 Acute hypoglycemia may increase latency and reduce amplitude of sensory-evoked potentials.¹⁰ These risk factors play an important part in identifying patients with diabetes who may be susceptible to cognitive impairment. Interestingly, Kuroki and coworkers found patients with one to 10 remaining teeth had increased cognitive impairment in comparison with patients with greater than 28 teeth.¹¹

Cognitive dysfunction can amplify the already well-known consequences of diabetes, most pertinently limb salvage. Lower extremity amputations in patients with diabetes often lead to a prolonged recovery period and, unfortunately, recidivism. Individuals with cognitive deficits experience significant difficulties in regaining mobility, prosthesis use, organizational skills and independence in daily living following lower extremity amputation.¹² Decreased memory, both visual and verbal, had a negative impact on the success of six months of rehabilitation following lower limb amputation in one study.¹³

Thein and colleagues found mortality was increased twofold in patients with diabetes with cognitive impairment in comparison to patients with diabetes without cognitive impairments.² This rate increased to nearly 13-fold when patients were both cognitively impaired and physically frail.²

While research has not shown any direct medications, other than appropriate glycemic control, to improve cognitive function in patients with diabetes, there are other methods to help these patients.¹⁴ If one is suspicious for a patient with diabetes of having cognitive dysfunction, it is warranted to ask the patient about home life, workplace and daily activities, and then refer the patient to the family practice physician for further evaluation.¹⁵ Moreover, a candid discussion on the risk of cognitive decline may motivate the patient to improve vigilance with glycemic control and diabetic foot health.¹⁵ Frequently, in practice, we find patients with diabetes are more likely to listen to counseling and treatments if we give them written instructions and handouts. Referral to diabetes counseling, both inpatient and outpatient, may also improve and help solidify the importance of glycemic control.

Following amputation or other surgeries, cognitive evaluation prior to rehabilitation could assist in determining suitable weightbearing status, establishing appropriate goals and customizing rehabilitation to meet a patient’s strengths in order to improve mobility and independence.¹²

Cognitive dysfunction associated with diabetes is becoming more frequently appreciated within the medical literature, especially over the last 10 to 15 years. However, there is limited research pertaining to diabetic cognitive impairment in the foot and ankle patient. Nonetheless, the existing literature tells us that comorbid patients with diabetes over 65 years old who also smoke are especially at risk. Evaluating cognitive impairment and risk factors at a diabetic foot screening and during a preoperative evaluation could greatly improve patient outcomes and overall quality of life.

Regardless, this aspect of diabetes has gone underappreciated for too long and deserves greater attention from the podiatric community if we hope to provide the best possible care in this ever evolving patient population.

Graham Rigby, DPM, coauthored this DPM Blog

References

1. Petersen RC, Caracciolo B, Brayne C, et al. Mild cognitive impairment: a concept in evolution. J Intern Med. 2014; 275(3):214–28.

2. Thein FS, Li Y, Nyunt MSZ, et al. Physical frailty and cognitive impairment is associated with diabetes and adversely impact functional status and mortality. Postgrad Med. 2018; 130(6):561–7.

3. Yuan XY, Wang XG. Mild cognitive impairment in type 2 diabetes mellitus and related risk factors: a review. Rev Neurosci. 2017; 28(7):715–23.

4. McCrimmon RJ, Ryan CM, Frier BM. Diabetes and cognitive dysfunction. Lancet. 2012; 379(9833):2291–9.

5. Marseglia A, Xu W, Rizzuto D, et al. Cognitive functioning among patients with diabetic foot. J Diabetes Complications. 2014; 28(6):863–8.

6. Cukierman T, Gerstein HC, Williamson JD. Cognitive decline and dementia in diabetes—systematic overview of prospective observational studies. Diabetologia. 2005; 48(12):2460–9.

7. Arvanitakis Z, Wilson RS, Li Y, et al. Diabetes and function in different cognitive systems in older individuals without dementia. Diabetes Care. 2006; 29(3):560–5.

8. Koekkoek PS, Kappelle LJ, van den Berg E. Cognitive function in patients with diabetes mellitus: guidance for daily care. Lancet Neurol. 2015; 14(3):329–40.

9. Muhli M, Sembian U, Bathiba, et al. Study of auditory, visual reaction time and glycemic control (HBA1C) in chronic type II diabetes mellitus. J Clin Diagn Res. 2014; 8(9):BC11–13.

10. Whitmer RA, Karter AJ, Yaffe K, et al. Hypoglycemic episodes and risk of dementia in older patients with type 2 diabetes mellitus. JAMA. 2009; 301(15):1565–72.

11. Kuroki A, Sugita N, Komatsu S, et al. The number of remaining teeth as a risk indicator of cognitive impairment: A cross‐sectional clinical study in Sado Island. Clin Exp Dent Res. 2018; 4(6):291–6.

12. Coffey L, O’Keeffe F, Gallagher P, et al. Cognitive functioning in persons with lower limb amputations: a review. Disabil Rehabil. 2012; 34(23):1950–64.

13. O’Neill BF, Evans JJ. Memory and executive function predict mobility rehabilitation outcome after lower-limb amputation. Disabil Rehabil. 2009; 31(13):1083–91.

14. Areosa Sastre A, Vernooij RW, Gonzalez-Colaco Harmand M, Martinez G. Effect of the treatment of Type 2 diabetes mellitus on the development of cognitive impairment and dementia. Cochrane Database Syst Rev. 2017; 6:CD003804.

15. Biessels GJ, Kerssen Am de Haan EH, Kappelle LJ. Cognitive dysfunction and diabetes: implications for primary care. Prim Care Diabetes. 2007; 1(4):187–93.

Editor’s note: For a related article, see “Does ‘Cognitive Neuropathy’ Contribute To Non-Adherence In Patients With Diabetes?” in the June 2018 issue of Podiatry Today.