Treatment of young subjects is of increasing concern due to accumulating evidence that daily use of oral finasteride has several severe adverse effects… Since finasteride inhibits T conversion into DHT, which is responsible for most androgen activity, it is plausible that prolonged finasteride use in predisposed individuals could simulate the effects of aging in young men. Since some of the effects of androgen inhibition cannot be reversed once local androgen levels are re-established, it is temping to speculate that patients could still suffer from adverse sexual effects several months or even permanently after finasteride discontinuation.
Neurosteroid levels in serum samples were quantified in 55 male veterans who had sustained a blast-related TBI in Iraq or Afghanistan (with or without loss of consciousness), and in 55 male control veterans who had been deployed to Iraq or Afghanistan but who had not sustained a blast-related TBI (matched for age, time of blood draw, and smoking status). Nonparametric statistical comparisons between groups were conducted for each neurosteroid (pregnanolone, pregnenolone, androsterone, allopregnanolone). Neurosteroid levels in sera were determined by a highly sensitive and specific gas chromatography/mass spectrometry (GC/MS) method, as previously described, 45 , 92 – 94 with modifications. One milliliter of serum was extracted three times in ethyl acetate prior to high-performance liquid chromatography purification utilizing tetrahydrofuran, ethanol, and hexane in the mobile phase. A subset of samples (30%) was injected in duplicate; mean intra-assay coefficients of variation in these duplicate subsets were less than 6% for all four neurosteroids. The limit of detection for this mass spectrometry method was 1–2 picograms for each neurosteroid.
In humans, levels of 5-HT 1A receptor activation in the brain show negative correlation with aggression,  and a mutation in the gene that codes for the 5-HT 2A receptor may double the risk of suicide for those with that genotype.  Serotonin in the brain is not usually degraded after use, but is collected by serotonergic neurons by serotonin transporters on their cell surfaces. Studies have revealed nearly 10% of total variance in anxiety-related personality depends on variations in the description of where, when and how many serotonin transporters the neurons should deploy.