Intensive multifactorial treatment and cognitive functioning in screen-detected type 2 diabetes--the ADDITION-Netherlands study: a cluster-randomized trial.

Aim: To assess whether an intensive multifactorial treatment can reduce cognitive decrements and cognitive decline in screen-detected type 2 diabetes.

Methods: The multinational ADDITION-study, a cluster-randomized parallel group trial in patients with screen-detected type 2 diabetes, compared the effectiveness of intensive multifactorial treatment (IT; lifestyle advice and strict regulation of metabolic parameters) with routine care (RC) on cardiovascular outcome. In The Netherlands randomization was stratified according to practice organization. Allocation was concealed from patients. The present study assessed the effect of IT on cognition through two neuropsychological assessments (NPA) on two occasions. The assessments took place three and six years after the start of the intervention. Non-diabetic controls served as reference group. The first NPA was performed in 183 patients (IT: 97; RC: 86) and 69 controls. The second NPA was performed in 135 patients (IT: 71; RC: 64) and 55 controls. Primary outcome was a composite score, including the domains memory, information-processing speed and attention and executive function. Comparisons between the treatment groups were performed with multi-level analyses.

Results: The first NPA showed no differences between the treatment groups (mean difference composite z-score: 0.00; 95%-CI -0.16 to 0.16; IT vs RC). Over the next three years cognitive decline in the diabetic groups was within the range of the reference group and did not differ between the treatment arms (difference decline between diabetic groups -0.12; -0.24 to 0.01; IT vs RC).

Conclusions: Six years of IT in screen-detected type 2 diabetes had no benefit on cognitive functioning over RC.