title: Cognitive decline in a patient with anti-glutamic acid decarboxylase autoimmunity; case report.
abstract: BACKGROUND
  Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme for producing γ-aminobutyric acid, and it has been suggested that antibodies against GAD play a role in neurological conditions and type 1 diabetes. However, it is not known whether dementia appears as the sole neurological manifestation associated with anti-GAD antibodies in the central nervous system.
  
  
  METHODS
  We describe the clinical, neuropsychological, and neuroradiological findings of a 73-year-old female with cognitive dysfunction and type 1A diabetes. Observation and neuropsychological studies revealed linguistic problems, short-term memory disturbance, and frontal dysfunction. MRI showed no significant lesion except for confluent small T2-hyperintensity areas localized in the left basal ganglia. ¹⁸F-fluorodeoxy glucose-positron emission tomography (FDG-PET) and ¹²³I-N-isopropyl-p-iodoamphetamine-single photon emission computed tomography (IMP-SPECT) studies showed bifrontal hypometabolism and hypoperfusion. Immunomodulating therapy with intravenous high-dose immunoglobulin resulted in no remission of the cognitive symptoms.
  
  
  CONCLUSIONS
  Cognitive dysfunction may develop as an isolated neurological manifestation in association with type 1A diabetes and anti-GAD autoimmunity. A systematic study with extensive neuropsychological assessment is indicated in patients with type 1 diabetes and anti-GAD autoimmunity.
authors.affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan. mastakagi@med.tohoku.ac.jp
authors.forename: Masahito
authors.initials: M
authors.lastname: Takagi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamasaki
authors.forename: Keiko
authors.initials: K
authors.lastname: Endo
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamada
authors.forename: Keizo
authors.initials: K
authors.lastname: Kaneko
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Oka
authors.forename: Etsuro
authors.initials: E
authors.lastname: Mori
mesh_terms: D000368:Aged; D015551:Autoimmunity / Q000276:immunology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use; D007806:Language Disorders / Q000276:immunology; D008279:Magnetic Resonance Imaging; D008569:Memory Disorders / Q000276:immunology; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography
chemical_list: D016756:Immunoglobulins, Intravenous; D005968:Glutamate Decarboxylase