title: Polymorphisms in the type I deiodinase gene and frontal function in recurrent depressive disorder.
abstract: OBJECTIVE
  Significant impairment of some psychological functions, including cognitive functioning, has been characteristically found in depressed patients. Memory disturbances may be related to the levels of thyroid hormones (TH) that are under the influence of different mechanisms and molecules, including deiodinase type 1(D1) - an important determinant of circulating triiodothyronine (T3). We investigated the relationship between two functionally known polymorphisms within the DIO1 gene, i.e. DIO1a-C/T and DIO1b-A/G, and cognitive functioning in patients diagnosed with recurrent depressive disorder (rDD). In the planned analysis we mainly concentrated on the frontal function: working memory, executive functions and verbal fluency.
  
  
  METHODS
  Genetic variants were genotyped in 128 patients using a method based on polymerase chain reaction (PCR). Cognitive functions were assessed by the Trail Making Test, the Stroop Test and the Verbal Fluency Test (VFT).
  
  
  RESULTS
  No significant associations were found between DIO1 polymorphisms and cognitive functioning in rDD. Only the CT and TT genotypes of the DIO1a variant were significantly related to verbal fluency. There were no significant differences between the distribution of the genotypes and demographic/medical variables.
  
  
  CONCLUSIONS
  Based on the study, the examined polymorphisms are not an important risk or protective factor for cognitive impairment in depressive patients. Functional variants within the DIO1 gene that affect triiodothyronine (T3) levels seem not to be associated with cognitive functions. Nevertheless, considering the fact that the DIO1 gene is related to the course and management of depression, further studies on a larger sample size might be suggested.
authors: Department of Pneumology and Allergy, Medical University of Łódź, Poland. Electronic address: galeckaela@wp.pl.
authors: Elżbieta
authors: E
authors: Gałecka
authors: Department of Adult Psychiatry, Medical University of Łódź, Poland.
authors: Monika
authors: M
authors: Talarowska
authors: Department of Adult Psychiatry, Medical University of Łódź, Poland.
authors: Agata
authors: A
authors: Orzechowska
authors: Department of Pneumology and Allergy, Medical University of Łódź, Poland.
authors: Paweł
authors: P
authors: Górski
authors: Department of Medical Biochemistry, Medical University of Łódź, Poland.
authors: Janusz
authors: J
authors: Szemraj
mesh_terms: D000328:Adult; D000368:Aged; D003071:Cognition / Q000502:physiology*; D003710:Demography; D003866:Depressive Disorder / Q000201:enzymology* / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D007453:Iodide Peroxidase / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012008:Recurrence; D055815:Young Adult
chemical_list: C109812:iodothyronine deiodinase type I; D007453:Iodide Peroxidase
keywords: Cognitive functions; Polymorphism; Recurrent depressive disorder; Type I deiodinase