title: Parkinson's disease and osteoporosis.
abstract: BACKGROUND
  patients with Parkinson's disease (PD) have a high risk of sustaining osteoporotic fractures as a result of falls and reduced bone mass.
  
  
  OBJECTIVE
  to summarise the underlying pathophysiological mechanisms of bone loss in PD by reviewing the available literature.
  
  
  METHODS
  a Medline search was performed for articles published between January 1975 and January 2011, using the keywords 'bone mineral density', 'bone loss', 'bone metabolism', 'osteoporosis', 'osteopenia', 'Parkinson's disease' and 'Parkinsonism'.
  
  
  RESULTS
  PD patients have a lower bone mineral density (BMD) than age-matched controls. Bone loss in PD is multifactorial, resulting from immobility, decreased muscle strength, and low body weight. Vitamin D deficiency is also important, not only because it reduces BMD, but also because cell function in the substantia nigra depends on vitamin D. Lastly, hyperhomocysteinaemia, an independent risk factor for osteoporosis, is common in PD, due to levodopa use, as well as vitamin B12 and folic acid deficiency. A few studies have demonstrated that treatment with bisphosphonates, vitamin D and calcium can increase BMD and reduce fractures in PD patients.
  
  
  CONCLUSIONS
  bone loss in PD is multifactorial. It is clinically important because of the concomitant risk of fractures. Screening for osteoporosis should be considered more often, and therapeutic interventions should be initiated.
authors.affiliation: Internal Medicine, Haga Hospital, Leyweg 275, The Haque 2545 CH, The Netherlands. f.vandenbos@hagaziekenhuis.nl
authors.forename: Frederiek
authors.initials: F
authors.lastname: van den Bos
authors.forename: Arlene D
authors.initials: AD
authors.lastname: Speelman
authors.forename: Monique
authors.initials: M
authors.lastname: Samson
authors.forename: Marten
authors.initials: M
authors.lastname: Munneke
authors.forename: Bastiaan R
authors.initials: BR
authors.lastname: Bloem
authors.forename: Harald J J
authors.initials: HJ
authors.lastname: Verhaar
mesh_terms: D000058:Accidental Falls; D000367:Age Factors; D000368:Aged; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D016723:Bone Remodeling; D001842:Bone and Bones / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D002118:Calcium / Q000627:therapeutic use; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D058866:Osteoporotic Fractures / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D010300:Parkinson Disease / Q000150:complications* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D018570:Risk Assessment; D012307:Risk Factors; D040242:Risk Reduction Behavior; D012737:Sex Factors; D016896:Treatment Outcome; D014807:Vitamin D / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000150:complications
chemical_list: D050071:Bone Density Conservation Agents; D014807:Vitamin D; D002118:Calcium