Among patients with type 2 diabetes, those with foot ulcers show cognitive impairment across all domains when compared with those without, according to a report published in Diabetes Care.

In what they described as one of the first studies to examine cognitive function in people with diabetic foot ulcers, researchers found that these patients “remember less, have decreased ability to concentrate, and more difficulty with learning, less inhibition, slower cognitive and psychomotor responses, and less verbal fluency” than patients with diabetes that does not include foot involvement.

Although this study had a cross-sectional design that precluded drawing conclusions about causality, an analysis that estimated the participants’ premorbid and postmorbid cognitive abilities suggested that people with diabetic foot ulcers had experienced a recent significant cognitive decline, while those without foot ulcers had not, said Rachel Natovich, Ph.D., of the department of public health, Ben-Gurion University of the Negev, Be’er Sheva (Israel) and the Endocrinology Institute, Sheba Medical Center, Ramat Gan (Israel) and her associates. These findings indicate that patients with diabetic foot ulcers – the very patients who face the greatest self-treatment challenges – are the ones who have the weakest cognitive resources to do so, they noted.

The investigators examined this issue after noting that recent consensus guidelines require patients with diabetic foot ulcers to take on even more self-management than is already required for the diabetes. This demands “applying complex cognitive abilities in learning, understanding, and remembering new information; planning and initiating self-care practices; adopting behavioral changes that involve psychomotor abilities; and maintaining these behaviors while controlling and repressing impulses.” So Dr. Natovich and her associates assessed whether the cognitive profile of patients who have diabetic foot problems differs from that of patients who don’t, using a case-control study design.

The 194 study participants were aged 45-75 years. The 99 subjects who had at least one diabetic foot ulcer (cases) were matched for age and duration of diabetes with 95 subjects who did not (controls). All underwent a comprehensive battery of neuropsychological tests assessing general intelligence, short- and long-term memory, attention and concentration, psychomotor efficiency, reaction time, executive function, nonverbal IQ, visual-motor speed, coordination, capacity for learning, verbal production, semantic memory, and language. All were also assessed for depression via the Patient Health Questionnaire.

After scores were standardized according to the expected performance by age and education level, patients with diabetic foot ulcers showed significantly lower scores in all the domains tested, compared with the patients without foot ulcers. This difference persisted after the data were adjusted to account for possible confounding factors such as smoking status, hemoglobin A1c level, presence or absence of depressive symptoms, and presence or absence of macrovascular disease ( Diab Care. 2016 May. doi:10.2337/dc15-2838 ).

The estimated premorbid cognitive function was similar between the two study groups, but current cognitive function declined significantly in the patients with foot ulcers while remaining relatively constant in the patients without foot ulcers. Prospective studies are needed to explore the timing of cognitive decline and the possibility of causation, Dr. Natovich and her associates said.

The study results “highlight the importance of focusing on cognitive functioning, a less-studied area in diabetic foot research,” they added.

“We feel that it is important to screen the cognitive status of these patients regularly and to take cognitive abilities into consideration in treatment-planning recommendations and follow-up.”