"Harms surrounding AAS are mostly discussed in general terms, while specific differences between compounds are seldom discussed. Underwood  posits that there is a need, particularly regarding trenbolone, to discuss individual compounds. Trenbolone is an AAS, derived from the nandrolone group but differing from nandrolone by an addition of a double bond between C10-C9 and C11-12 . Although originally used by veterinarians on livestock to increase muscle growth and appetite , injectable trenbolone was originally adapted for use by bodybuilders from the dissolution of Finaplix H pellets  who refer to the compound as ‘tren’. Trenbolone was not originally designed for oral routes of administration . Further, the liver readily metabolises natural AASs except when that AAS has been modified to pass through the liver without destruction, known as 17-alkylated AAS  of which trenbolone is not one, and therefore is commonly injected by users [7, 12]. Trenbolone possesses strong anabolic properties and nutrient partitioning effects, boosts the mineral absorption and improves lean muscle mass  and, therefore, is often used to enhance the strength gains and protein synthesis which comes from strength training . It has also been found to have the secondary effects of stimulating appetite, reducing fat deposition and decreasing the rate of catabolism . Trenbolone likely represents an attractive option to AAS users given it has been found to be significantly more potent than testosterone . Specifically, trenbolone has a binding affinity for the androgen receptor three times as high as testosterone . Trenbolone is available in a number of preparations: the shortest esterified version available is trenbolone acetate, with a half-life of 1–2 days; trenbolone hexhydrobenzylcarbonate, which has a half-life of approximately 8 days; and trenbolone enanthate, which has a half-life of 11 days . Trenbolone and nandrolone are considered to be closely linked given they are both 19-Nor AAS [1, 16].
"Treatment with 19-Nor AAS—nandrolone group—can cause significant alterations in the density of serotoninergic receptors in animals  leading to an established AAS-serotonin link which is believed to underpin why AAS are associated with changes in emotional states and behaviour . Trenbolone, specifically, has been linked with not only cardiovascular issues  but also with extreme instances of violence . Short term side effects of trenbolone which have been identified include insomnia, high blood pressure and increased aggression and libido . Research has suggested these instances of psychological and emotional instability are attributable to modulated serotonin receptor activity and associated with decreased serotonin neurotransmission . Indeed, nandrolone and trenbolone (the two 19-Nors)  have been identified as the most neurotoxic of AAS  and, therefore, warrant further exploration in the risk profile for psychological harm to users."
Piatkowski TM, Neumann DL, Dunn M. 'My mind pretty much went to mush': A qualitative exploration of trenbolone in the performance and image enhancing drug community. Drug Alcohol Rev. 2023;42(6):1566-1576. doi:10.1111/dar.13656