RESUMO
Low plasma folate and its derivatives have been linked with depressive disorders in studies dating back over 30 years. A thermolabile variant (677C>T) of the enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) is associated with low serum folate. The present study aimed to explore whether the thermolabile variant of MTHFR is associated with a vulnerability to depressive episodes. MTHFR C677T genotype frequencies in a cohort of patients (mean age 48 years) with depressive disorder (n = 100) were compared with those in age- and sex-matched controls. Serum levels of folate, homocysteine and vitamin B(12) were also compared between groups. The thermolabile variant of MTHFR was significantly more common in the group with a history of depressive disorder (P= 0.03). Serum levels of folate, homocysteine and vitamin B(12) did not differ significantly between groups. A MTHFR C677T genotype is associated with increased risk of depressive episodes in this homogenous patient population.
Assuntos
Transtorno Depressivo/genética , Transtorno Depressivo/psicologia , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Polimorfismo Genético/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Transtorno Depressivo/epidemiologia , Feminino , Ácido Fólico/sangue , Frequência do Gene , Genótipo , Homocistina/sangue , Humanos , Irlanda/epidemiologia , Masculino , Pessoa de Meia-Idade , Vitamina B 12/sangueRESUMO
The associations of folic acid and its derivatives with depressive disorder are reviewed. Derivatives of folic acid such as biopterins and the synthesis of S-adenosyl methionine (SAM) are known either to be associated with improvement or to have a direct therapeutic effect in depressive disorder. Studies investigating plasma and red cell folic acid levels in depressed patients have used differing assay methodologies which make comparison difficult, although there is substantial evidence of the association between depressive disorder (particularly severe depression) and low folic acid levels. The few studies available suggest folic acid has either antidepressant properties or can act as an augmenting agent for standard antidepressant treatment. A recently discovered genetic variant (5,10 MTHFR) leading to altered folic acid metabolism may explain why some individuals are vulnerable to the effects of folic acid deficiency, despite adequate intake. The links of 5,10 MTHFR to the presence of depressive disorder in the community are being investigated.
