Association of muscle and visceral adipose tissues with the probability of Alzheimer's disease in healthy subjects

Abstract

Increasing evidence indicates that sarcopenia and obesity can be risk factors for incident dementia. We investigated the association of body composition including muscle and visceral adipose tissue (VAT) with the probability of Alzheimer's disease (AD) in healthy middle-aged and elderly subjects using ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). This study included 110 healthy subjects with available whole-body FDG PET/CT scans and medical records. Muscle and VAT tissues were measured on the abdominal CT slice, and the PMOD Alzheimer's discrimination FDG PET analysis tool (PALZ) score was evaluated on the brain PET of the same subject using software PALZ. Skeletal muscle index (r: -0.306; P = 0.031) was significantly negatively associated with the PALZ score in the elderly patients. Muscle area (β: -0.640; P = 0.043) and skeletal muscle index (β: -0.557; P = 0.043) were independently associated with the PALZ score in elderly subjects after adjustments for sex, duration of education, hypertension, diabetes mellitus, and smoking and drinking status. Increased muscle tissue was associated with a lower probability of AD in elderly subjects, but VAT was not associated with a lower probability of AD in middle-or older-aged adults.

Figure 1

Box plots of the PALZ scores of the midlife and late-life groups according to clinical characteristics. The PALZ score differences according to sex, history of hypertension or diabetes mellitus, and smoking and drinking habits in between the mid-life and late-life groups were not significant (all P > 0.05). PALZ; PMOD Alzheimer’s discrimination.

Figure 2

Representative cases. (A) A healthy 72-year-old man (education: 12 years, height: 165 cm, body weight: 60 kg, BMI: 22.0 kg/m²), (B) A healthy 73-year-old man (education: 12 years, height: 165 cm, body weight: 85 kg, BMI: 31.2 kg/m²). BMI, body mass index; VAT, visceral adipose tissue; HU, Hounsfield unit; PALZ, PMOD Alzheimer’s discrimination.