Neuropsychological function in individuals with morbid obesity: a cross-sectional study

Previous research has shown cognitive dysfunction to be present in a significant number of individuals with obesity. The objective of this study was to assess the neuropsychological profile of morbidly obese patients referred to weight-loss treatment.

An extensive battery of neuropsychological tests with well-known normative data covering various cognitive domains was administered to 96 patients. The test results were transformed to z-scores for comparisons with normative data. As a means of determining level of cognitive impairment within the group, deficit scores were applied. Group comparisons on the different cognitive domains were conducted between patients with depressive symptoms and patients reporting no such symptoms.

As illustrated in mean z-scores, the patients demonstrated lower performance compared to normative data on visual memory (mean -.26, CI -.43 to -.09, p = .003), speed of information processing (mean -.22, CI -.34 to -.09, p = .001), executive functions (mean -.28, CI -.40 to -.16, p < .001), and attention/vigilance (mean -.25, CI -.37 to -.13, p < .001). Their performance was good on verbal fluency (mean .24, CI .04 to .44, p = .016) and verbal memory (mean .55, CI .38 to .72, p < .001). No significant performance differences were observed in the cognitive domains of visuospatial ability, motor function, and working memory. The deficit scores, however, revealed working memory and motor function to be significantly impaired within the group as well. Patients with depressive symptoms differed from patients without such symptoms on visual memory (mean .43, CI .07 to .80, p = .021).

Some characteristic cognitive weaknesses and strengths were evident at the group level, although pronounced variation was observed. Deficits in executive functions, information processing, and attention should be taken into consideration in clinical practice.