Leptin, interleukin levels and nutritional status in Alzheimer’s Disease: a Case-Control study/ Leptina, níveis de interleucinas e estado nutricional no Mal de Alzheimer: um Estudo de Caso-Controle

Abstract

Objective: to compare the circulating/ serum levels of pro-inflammatory and anti-inflammatory cytokines and levels of leptin between Alzheimer’s disease (AD) patients and healthy older adults, correlating the levels of cytokines and leptin with nutritional status and global cognition. Methods: A case control study, which 32 older adults participated in the study, divided in two groups: AD Group (AD; n=16) and Non-dement older adults as Control Group (CG; n=16). The groups were paired by age, sex and comorbidities in relation to AD group. To identify the levels of cytokines and leptin, Enzyme linked immune sorbent assay were used. The Mini-Nutritional Assessment was used to measure the nutritional status and the Mini-Mental State Exam, global cognition. Comparisons between the case-control groups were performed by t-test and Hedge’s g effect size was calculated. Pearson's correlation test was used to analyze the associations between the observed and paired differences. Simple linear regression was applied in functional relationship between the variables. Results: The Alzheimer’s disease group and Control Group were different to all of interleukins and leptin. A negative very strong relationship between leptin and BMI was found in Alzheimer’s disease group (R 2 :-0.6425; p<0,05), but not in Control Group. No associations were found among global cognition, MMSE, interleukins and nutritional status. Conclusion: The AD patients had higher levels of proinflammatory interleukins, and lower levels of anti-inflammatory interleukin and leptin compared to older healthy adults, which suggest an immune system unbalanced. The reduced leptin serum levels were associated with increase body mass index, which suggests that in Alzheimer’s disease the reduce of leptin is associated with increase BMI.