Parkinson's disease and body mass index: too much or too little?

Abstract

Parkinson's disease (PD) is the second most common degenerative disease, being characterized by the presence of motor and non-motor symptoms. The former include bradykinesia, rigidity, tremor and postural instability; the latter include depression, sleep disorders, hyposmia, constipation, cognitive dysfunction, dementia and body mass index (BMI) abnormalities 1 . The relationship between BMI and PD is very controversial. In 2010, Hawkes et al. defined a timeline for PD based on the Braak pathological staging ( from stage 1 to 6) and suggested that different brain stem structures are involved in the prodromal phase (estimated to be 20 years) 2. In stage 2, in which there is involvement of the coeruleus/subcoeruleus complex (CSC), the magnocellular portions of the reticular formation and the dorsal raphe nuclei, authors suggested that sleep disorder (REM sleep behavior disorder), depression and obesity are present However, some studies suggest that patients with advanced PD present with malnutrition and lower BMI in relation to controls for several reasons, including the presence of dysphagia, dyskinesia, depression and cognitive problems [3][4][5] . Cassani et al. studied serum adiponectin levels in advanced-stage PD patients with body weight loss and found significantly higher levels of this protein in PD patients than in controls . This pooled data from seven studies and demonstrated that PD patients had a significantly lower BMI than controls, and that patients at Hoehn-Yahr stage 3 had lower BMI in comparison to patients at stage 2 7 . Fiszer et al. studied leptin and ghrelin concentrations (produced respectively in the adipose tissue and mainly in the stomach) in PD patients with weight loss 8 . The findings in this interesting study, in which plasma leptin levels were reduced and IGF-1 levels were elevated, confirm that altered plasma leptin concentrations are common in PD patients. Altered plasma concentrations of orexigenic and anorexigenic peptides (ghrelin and leptin, respectively) lead to alterations in the hypothalamic-pituitary axis 8 . However, PD patients who undergo neurosurgery for a deep brain stimulation (DBS) implant in the subthalamic nucleus can exhibit significant weight gain, underscoring the complex interaction between the hypothalamic-pituitary axis and the basal ganglia 3,5,7,9 . Markali et al. studied the role of ghrelin, neuropeptide Y and leptin in PD patients who had weight gain after DBS implant surgery 9 . They concluded that the introduction of a DBS implant in the subthalamic nucleus temporarily deregulated the hypothalamic secretion of neuropeptide Y and ghrelin, and that weight gain was therefore the result of increased production of ghrelin and leptin 9 .In the current issue of Arquivos de Neuro-Psiquiatria, Morales-Briceño et al. published a very interesting study about overweight PD patients 10 . The authors carried out a cross-sectional study with 177 healthy controls and 177 PD patients. Analyzing BMI, they found that overweight