Int J Neurosci. 2001;111(1-2):1-9. Related Articles, Links
Testosterone and nonverbal intelligence in right-handed men with successful and unsuccessful educational levels.
Kutlu N, Ekerbicer N, Ari Z, Uyanik BS, Zeren T, Tan U.
Department of Physiology, Medical School, Celal Bayar University, Turkey.
The relationship between serum total testosterone (T) concentration and fluid intelligence (nonverbal, spatial) was studied in consistently right-handed men with successful (S) or unsuccessful educational levels (NS). Hand preference was assessed by the Edinburgh Handedness Inventory. Nonverbal intelligence was measured by Cattell's Culture Fair Intelligence Test. Serum T level was determined using chemiluminescence enzyme-immunoassay on hormone autoanalyzer. There was no significant difference between the mean T levels of the S subjects and NS subjects, although S-men tended to have higher T levels than NS-men. The mean IQ was found to be significantly higher in S-men than NS-men. In the total sample (S + NS men), the correlation between T to IQ was best described by a polynomial regression (3rd order), exhibiting an inverse U-shaped regression. In S-men, the relationship between T and IQ was best described by a polynomial regression equation of the 3rd order; however, the relationship was not U-shaped, but rather a positive correlation
(low T: low IQ and high T high IQ). In NS-men, there was an inverse U-shaped correlation between T and IQ (low and very high T: low IQ and moderate T: high IQ). The present data suggest that (i) very low and very high serum T concentrations may be disadvantageous, (ii) moderate T levels may be advantageous for general fluid intelligence, and (iii) a prewired cerebral organization may be essential for the T effects on cognitive abilities.
Curvelinear correlations between total testosterone levels and fluid intelligence in men and women.
Tan U, Tan M.
Department of Physiology, Medical Faculty, Ataturk University, Erzurum, Turkey.
unertan@superonline.comThe relationship between serum total testosterone (T) level and fluid intelligence (Cattell's Culture Fair Intelligence Test) was studied in young men and women. There was no significant difference between IQs of men and women.
IQ tended to increase with T in men, except at very high T levels. It was concluded that (i) T may be associated with IQ, even in samples with no sex-related IQ difference; (ii) too low or too high T may be disadvantageous for fluid intelligence in women; (iii) T may be advantageous for this kind of IQ in men, except very high T levels.
Testosterone and nonverbal intelligence in right-handed men and women.
Tan U.
Ataturk University, Medical Faculty, Institute of Physiology, Erzurum, Turkey.
The relationship between serum testosterone level and nonverbal intelligence was studied in right-handed young adults. Hand preference was assessed by the Edinburgh Handedness Inventory. Serum testosterone level was determined using tritium-marked-radioimmunoassay. Only in men, nonverbal intelligence (Cattell's Culture Fair Intelligence Test) was found to be significantly and directly related to serum testosterone levels.
It was concluded that the serum testosterone in young adults is associated with nonverbal intelligence exhibiting fundamental differences between men and women
