Introduction
What comes to your mind when asked about testosterone? Probably lust, violence, and machismo. Testosterone is simply a steroid hormone found in males and is responsible for their aggressiveness, and at times can be associated with antisocial and negative male behaviour. Therefore, this paper aims to evaluate the role of testosterone in human behaviour and cognition.
Human Behavior
Testosterone has several effects on human behaviour, and they include;
- Effect of testosterone on aggression and mood
According to research, increased levels of circulating testosterone in men cause increases in male-typical behaviors such as rage and violence (Crespi, 2016). Although this study might appear conclusive, they are many retrospectives, observational, and or cross-sectional, thus making it improbable to derive conclusions based on causal relations between male behaviours and testosterone (Barry & Owens, 2019; Clarkson & Herbison, 2016). Another research reveals that ingesting supraphysiological amounts of testosterone results in increased measures of anger, direct aggression, and mood swings (Chegeni et al., 2019).
- Testosterone hormone and Sexual behaviour
Testosterone plays a significant role in governing sexual behaviours in humans. This point is demonstrated by early behavioural evidence that shows hypo-gonadal men exhibiting impaired sexual functioning due to their low or no circulating testosterone, or even abnormal functioning of the gonadal (Pringle et al., 2017). The evidence further shows that once these men are taken through testosterone replacement therapy, then their sexual function is returned to normal (Barbonetti, D’Andrea & Francavilla, 2020). Even so, the weight of evidence asserts that administering testosterone restores sexual functioning in men with lower testosterone levels, however, it is also quick to elucidate that this is not true in men with testosterone higher than normal.
- Testosterone influences brain behavioural functions
This hormone is responsible for controlling certain behavioural manifestations such as depression and anxiety. Research reveals that women exhibit higher levels of anxiety compared to men. This is compounded by the revelation that in all behavioural factors, anxiety appears to the sensitive towards testosterone (Ciocca et al., 2016). Another research that delved on the effects of testosterone in mice revealed that whether testosterone is induced exogenously or endogenously, it decreased anxiety (Crespi, 2016). Therefore, high levels of testosterone in men is the main reason why anxiety is felt differently between sexes.
Despite the fact that depressive illnesses are more prevalent in women than in males, the latter’s prevalence of depression rises with age, especially when plasma testosterone levels fall. Furthermore, in depressive disorders that are characterized by low testosterone and low libido, research indicates that androgen replacement therapy was ineffective in performing the function of serotonin reuptake (Huo et al., 2016). In doing so, testosterone was found to modulate the transmission of serotonin, which is crucial in the development of depression. Thus, observational studies conducted on elderly men showed that their low production of plasma testosterone in late years was associated with an increase in depressive symptoms (J Wahjoepramono et al., 2016). Hence, such scenarios could lead to risky falls that might have a significant impact on their life expectancy.
The modulation of the human emotion circuit is significantly affected by the gonadal hormone. A good example is how for many years the male sex hormone has been linked with undesirable behaviours within society like risk-taking and aggression. Studies indicate a complicated role adopted by testosterones, with one recent one suggesting that testosterone plays a more complicated function in human interactions, influencing happy emotions and promoting cooperative and prosocial conduct (Yang et al., 2021). Endogenous testosterone levels appear to regulate the amygdala prefrontal cortex connection based on the similarity of emotional responses and changes in an emotional state. The findings could show that testosterone affects brain connections involved in emotion processing and control, as well as aggression-related cognition. Numerous studies have shown that testosterone injection causes an increase in furious, aggressive, and impulsive conduct (Votinov et al., n.d.).
Low testosterone levels are known to be associated with a socially subservient, anxious, and emotionally distant attitude, whilst high levels of testosterone have been linked aggressive behaviour. Lower levels of endogenous testosterone have been associated with a social anxiety disorder (Giltay et al., 2012), as well as other social avoidance-related disorders like depression. Additionally, testosterone possesses social motivation properties that aid in the reduction of apprehensive behaviour, the enhancement of reward sensitivity, and the promotion of social approach motivation. When given to people with social anxiety disorder, testosterone reduces social avoidance and encourages prosocial behaviour, such as more eye contact and a more aggressive approach to furious faces. Furthermore, testosterone therapy lowers social anxiety disorder patients’ instinctive threat bias toward furious faces (Hutschemaekers et al., 2020).
There is also proof that lower testosterone males are increasingly likely to participate in prosocial conduct than men with higher testosterone levels. The testosterone levels of better-provider fathers are lower, which is contrary to the testosterone levels present in men in high-conflict marriages. Men who become committed fathers have lower testosterone levels, which can make paternal care more difficult. Fathers with lower baseline testosterone levels have a high probability to engage in better parenting. When matched to other fathers in their neighbourhood, fathers who were viewed as better breadwinners possessed more testosterone. When men help raise children, testosterone levels are usually elevated during mating and competition (Boyette et al., 2019).
Testosterone appears to play a crucial role in social interactions in both biosociological and psychological theories. Testosterone is linked to aggressive behaviour in conspecifics, according to research. Folk wisdom generalizes and adapts these findings to humans, implying that testosterone causes antisocial, egoistic, or even hostile human behaviour. In difficult social interactions, testosterone is predominantly responsible for status-related behaviours. Subjects who thought they were given testosterone acted substantially more unequally than those who thought they were given a placebo.
Human Cognition
A large number of scientific investigations have revealed profound sex variations in the human brain, with significant behavioural and cognitive repercussions, over the last few decades. Prenatal and postnatal testosterone have different effects on functions and brain architecture. Certain spatial and verbal activities are particularly affected by cognitive sex differences, but they also affect many other areas of the neurotypical brain. The pathophysiology of neuropsychiatric illnesses such as autism spectrum disorders, which are substantially more prevalent in the male population, is also affected by gender variations in the brain. The typical male brain is more geared towards linking sensory perception with coordinated motor activity, whereas the average female brain is built for greater communication between analytic and intuitive thinking. Testosterone, often known as the sex and aggression hormone, is a neurochemical that has a significant impact on the structure and functioning of the brain.
- The Effects of Testosterone on Intelligence
Males produce far more testosterone than females, which sets off a chain reaction that results in the masculinization of genital tissue and the developing neurological system. Testosterone appears to affect the structure and architecture of the brain, according to evidence. Males are more likely to be affected by neurodevelopmental problems, such as severe mental retardation, language issues, learning difficulties, and others, regardless of race or disability severity. The scientists concluded that testosterone levels that are too low or too high can be detrimental to fluid intelligence (Ostatnková et al., 2020). Men’s memory is linked to testosterone deficiency, and testosterone supplementation can improve memory and spatial cognition.
- Testosterone and certain mental abilities
Men, on the contrary, have a little edge in visuospatial abilities, numeracy, and visual memory (Hyde 2014; Vidal et al. 2006). Sex hormones, among other things, may have a role in these cognitive disparities. In terms of spatial aptitude, adult men generally surpass women. Mental rotation, in particular, demonstrates a sex difference in favour of men. Despite the fact that some authors suggest that androgens’ impact on human performance on mental rotation tasks is restricted to early organizational phases, there is some evidence that there is a link between real testosterone and mental rotation performance.
Testosterone appears to have an impact on neurobiological processes linked to cognitive ageing and the onset of neurodegenerative diseases like Alzheimer’s disease. Testosterone is reported to delay neuronal death, speed nerve regeneration, control oxidative stress-induced neuronal damage, employ anti-inflammatory effects, and decreased amounts of beta-amyloid peptide, among other things. Second, beginning in the third decade, mental performance deteriorate in tandem with a fall in male levels of testosterone due to age. Third, studies show that men with prostate cancer who are treated with androgen restriction treatment have a greater risk of cognitive decline and dementia. than those who receive other types of treatment. In light of this, testosterone supplementation (TS) may be able to help men boost their cognitive abilities (Buskbjerg et al., 2019).
Testosterone has an important influence on the brain’s structure and function Androgen receptors can be found in critical parts of the brain such as the hippocampus and prefrontal cortex, which are crucial for higher-order cognitive functions. Surprisingly, animal research have revealed that gonadectomy (surgical excision of one or both testes) reduces acetylcholine in the hippocampal and anterior cingulate cortex while briefly reducing dopaminergic innervation in the cerebral hemisphere. Both neurotransmitters are important for learning and memory, and they appear to play a role in understanding how testosterone impacts cognitive functions (Nunez et al., 2019).
Furthermore, prenatal androgen exposure has been linked to sex differences in mental rotation. Females with high prenatal androgen exposure, such as those with congenital adrenal hyperplasia or those with a male twin, have stronger mental rotation ability than control females. These data imply that prenatal androgens may have an impact on postnatal cognition. Nonetheless, it appears that androgens have the greatest impact on brain growth at important developmental phases such as pregnancy, puberty, and middle age. Men’s testosterone levels and cognitive performance both diminish as they get older. It’s uncertain if testosterone and cognitive performance have more than a transient link. Low blood testosterone has been linked to cognitive impairment in males with prostate cancer, according to chemical castration studies. Low testosterone levels have been documented in people with Parkinson’s disease and mild cognitive impairment (MCI). Low endogenous testosterone levels have been found to lose of cognitive function, and testosterone replacement therapy can help to improve a variety of cognitive abilities. Blood levels of testosterone should be examined in elderly men with cognitive decline. For males with both memory loss and low levels of testosterone, testosterone replacement therapy may be considered. There is a need for large-scale, long-term evidence on the effects of testosterone therapy treatment on mental function in older men.
- Testosterone effect in the adult brain
The enzyme aromatase converts testosterone to estradiol, or it might be converted to dihydrotestosterone, which binds to androgen receptors. Aromatase and androgen receptors can be found in the hippocampus and amygdala, which are important memory and learning centres. NGF receptors in the frontal cortex and nerve growth factor (NGF) concentrations in the hippocampus are greatly enhanced by testosterone. Androgens can aid in the healing of neurons following injury by decreasing N-methyl-D-aspartate receptor excitotoxicity and increasing fibre outgrowth and sprouting. The brain’s neuroprotective abilities against oxidative and apoptosis may also shield it against increased age-related cognitive decline. Testosterone may protect the brain from Parkinson disease by preventing the buildup of b-amyloid in amyloid deposits and hyperphosphorylated tau in neurofibrillary, both of which are hallmarks of the disease. Testosterone has been demonstrated to reduce the release of b-amyloid in rat cortical neurons via altering the metabolism of the amyloid precursor. Testosterone reduces b-amyloid-induced neurotoxicity in hippocampus neurons cultured in vitro (Beauchet, 2006).
Empathic systematization. Furthermore, lower testosterone levels have been suggested as a possible cause of females’ superior cognitive empathy abilities.
In the end, the paper examined the impact of testosterone in human behaviour, and found it to be significant. Both on the positive end as well as on the negative side.
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