Prevalence of malnutrition in patients with Alzheimer's disease - A systematic review. The call for consistent nutritional assessment methods.

Introduction: Objectives: epidemiological data show growing numbers of patients with Alzheimer´s disease. Cognitive decline and progressive swallowing impairment lead to a significant deterioration of the nutrition status in this population. Early detection and treatment of malnutrition is important for the prognosis of the disease. Method: a systematic review was conducted. Four databases such as Cochrane, PubMed, Embase and Web of Science were searched by two independent researchers. The inclusion criteria encompass adult patients with diagnosed Alzheimer's disease, studies with screening tools for nutritional assessment such as Mini-Nutritional Assessment and body mass index. Patients without diagnosis or with possible or probable Alzheimer's disease were excluded. Finally, 36 studies with 5293 participants were included to the systematic review. PRISMA protocol was followed when writing this article. Critical Appraisal tools for use in JBI Systematic Reviews were used for quality assessment. Results: 36 studies were included in this systematic review. More than half of the respondents were from Europe. According to MNA 33.97 % of participants were at risk of malnutrition, 3.74 % malnourished and more than 62 % had proper nutritional status. According to the BMI, nearly 50 % of patients were overweight or obese, 4.22 % had BMI < BMI < 18,49 kg/m2. Risk of malnutrition and malnutrition was diagnosed in 53.8 % and 8.2 % of patients assessed with Mini-Nutritional Assessment - Short Form. Conclusion: the risk of malnutrition in AD is high, however, significant differences between studies can be observed due to methodological differences. Large epidemiological studies are needed with unified nutritional assessment methods for patients with Alzheimer's disease.