“…(Ceballos, et al, 2009) Epidemiological studies indicated that thyroid dysfunction whether hypo- or hyper-thyroidism (overt or subclinical) increases the risk of cognitive impairment,(Beydoun, et al, 2013,Bono, et al, 2004,Correia, et al, 2009,Miller, et al, 2006,Munte, et al, 2001) although the evidence is still sparse. (Almeida, et al, 2007,Ceresini, et al, 2009,de Jongh, et al, 2011,Formiga, et al, 2014,Joffe, et al, 2013,Kramer, et al, 2009,Parle, et al, 2010,Samuels, et al, 2007,Wijsman, et al, 2013) It is less well-known how thyroid hormone fluctuations within normal ranges can affect cognitive outcomes in the general population, particularly when studies have examined cognitive performance among middle-aged adults. (Beydoun, et al, 2013,Beydoun, et al, 2012,Grigorova and Sherwin, 2012,van Boxtel, et al, 2004)…”