title: The effects of cystatin C and alkaline phosphatase changes on cognitive function 12-months after bariatric surgery.
abstract: BACKGROUND
  The mechanisms for improved cognitive function post-bariatric surgery are not well understood. Markers of kidney and liver function (i.e., cystatin C and alkaline phosphatase (ALP)) are elevated in obese individuals and associated with poor neurocognitive outcomes in other samples. Bariatric surgery can improve cystatin C and ALP levels, but no study has examined whether such changes correspond to post-operative cognitive benefits.
  
  
  METHODS
  78 bariatric surgery patients completed a computerized cognitive test battery prior to and 12-months after surgery. All participants underwent an eight-hour fasting blood draw to quantify cystatin C and ALP concentrations.
  
  
  RESULTS
  Cognitive function improved after surgery. Cystatin C levels decreased at the 12-month follow-up; however, no changes were found in ALP concentrations. At baseline, higher cystatin C levels predicted worse attention/executive function, but no such effects emerged for ALP. Regression analyses controlling for possible medical and demographic confounds and baseline factors revealed that decreased ALP levels following surgery predicted better attention/executive function and memory abilities. Post-surgery changes in cystatin C did not correspond to cognitive improvements.
  
  
  CONCLUSIONS
  Decreased ALP levels predicted better cognition following bariatric surgery, suggesting improved liver function as a possible mechanism of post-operative cognitive benefits. Future studies with neuroimaging and longer follow-up periods are needed to determine whether bariatric surgery can decrease risk for adverse brain changes and dementia in severely obese persons via improved metabolic function.
authors: Kent State University, Kent, OH, United States.
authors: Michael L
authors: ML
authors: Alosco
authors: Kent State University, Kent, OH, United States.
authors: Mary Beth
authors: MB
authors: Spitznagel
authors: Weill Cornell Medical College, New York, NY, United States.
authors: Gladys
authors: G
authors: Strain
authors: Columbia University Medical Center, New York, NY, United States.
authors: Michael
authors: M
authors: Devlin
authors: University of Florida Institute on Aging, Gainesville, FL, United States.
authors: Ronald
authors: R
authors: Cohen
authors: University of North Dakota School of Medicine and Health Sciences, Neuropsychiatric Research Institute, Fargo, ND, United States.
authors: Ross D
authors: RD
authors: Crosby
authors: University of North Dakota School of Medicine and Health Sciences, Neuropsychiatric Research Institute, Fargo, ND, United States.
authors: James E
authors: JE
authors: Mitchell
authors: Kent State University, Kent, OH, United States. Electronic address: jgunstad@kent.edu.
authors: John
authors: J
authors: Gunstad
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000704:Analysis of Variance; D001288:Attention; D050110:Bariatric Surgery / Q000379:methods*; D003071:Cognition / Q000502:physiology*; D055316:Cystatin C / Q000378:metabolism*; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D009765:Obesity / Q000601:surgery; D011184:Postoperative Period; D014706:Verbal Learning
chemical_list: D055316:Cystatin C; D000469:Alkaline Phosphatase
keywords: Alkaline phosphatase; Bariatric surgery; Cognitive function; Cystatin C; Metabolic function; Obesity