title: Testosterone effect on brain metabolism in elderly patients with Alzheimer's disease: comparing two cases at different disease stages.
abstract: OBJECTIVE
  To describe the effect of testosterone replacement therapy (TRT) on the brain activity of two demented, hypogonadal male patients with early and late-stage Alzheimer's disease (AD), respectively.
  
  
  METHODS
  We describe the clinical and positron emission tomography (PET) findings for two individuals, one with early stage and the other with late-stage Alzheimer's disease, before and after treatment with a topical testosterone gel. Both patients were hypogonadal at baseline. We assessed cerebral glucose metabolism (CGM) via (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET). We investigated whether there are testosterone-susceptible areas within cerebral structures in patients with Alzheimer's disease.
  
  
  RESULTS
  Under testosterone replacement therapy, changes in cerebral glucose metabolism were observed in both patients. Improvement in glucose uptake was observed most consistently in the parietal lobe and brainstem; decreased glucose metabolism was observed in the temporal lobe, the limbic system and the insula for these two subjects.
  
  
  CONCLUSIONS
  These case reports demonstrate the potential for PET scanning to detect changes in cerebral glucose metabolism in hypogonadal men with Alzheimer's disease who are treated with testosterone. Further study will be needed to investigate the consistency and significance of these changes in terms of magnitude and brain region, and the correlation with functional changes.
authors.affiliation: Michel E DeBakey VA Medical Center, 2002 Holcombe Blvd, Mail Code ECL-110, Houston, TX 77030, USA. rstan@bcm.edu
authors.forename: R S
authors.initials: RS
authors.lastname: Tan
mesh_terms: D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D000544:Alzheimer Disease / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D018450:Disease Progression; D005947:Glucose / Q000378:metabolism; D020249:Hormone Replacement Therapy; D006801:Humans; D007006:Hypogonadism / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D049268:Positron-Emission Tomography; D013739:Testosterone / Q000494:pharmacology* / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D013739:Testosterone; D005947:Glucose