Introduction 

Alexithymia is a complex personality trait construct disorder, that encompasses three main cognitive deficits: difficulty identifying feelings, difficulty describing feelings, and externally oriented thinking (Salminen, Saarijärvi, Äärelä, Toikka, & Kauhanen, 1999). This construct was coined by Nemiah and Sifneos in the early 1970s, when they observed common emotional characteristics in psychosomatic patients. There are two theories proposed as to how alexithymia is developed: the first is that alexithymic characteristics are derived from deficits in the cognitive processing and regulation of emotions, and contribute to several medical psychiatric and medical disorders, and the second is that alexithymia is due to global impairment of emotional processing, leading to limited emotional expression and recognition (Lumley, Neely & Burger, 2007). Both theories suggest a deficit in emotional processing, but in the last few years, research has become more inclined to the first theory, due to the research showing that emotions can have an effect on more than just the mind, but the physical body as well (Lumley et al., 2007).  Alexithymia is a cross-cultural phenomenon and has been estimated to affect roughly 10 percent of the world’s population (Linden, Wen & Paulhus, 1994). However, it has been shown that prison populations have a higher prevalence, with the average being around 31-35 percent in both males and females around the world (Louth, Hare, & Linden, 1998, Chen, Xu, You, Zhang, & Ling, 2017). Research suggests that alexithymia could be higher in this population due to traumatic events experienced by many prisoners early on in their lives, such as childhood abuse (physical, mental, emotional), neglect, stress, or other untreated mental disorders (Chen et al., 2017). Unfortunately, for those who suffer with alexithymia, there is no cure. Behavioral therapies can be used to try and help reprogram and retrain the brain, but none of these programs have been very successful (Sifneos, 1983).

Alexithymia has a high comorbidity with other psychiatric disorders, a common one being psychopathy. Psychopathy is a multifaceted personality disorder, with a key component being emotional dysregulation and social norm deviance. Psychopaths are thought to make up roughly 1 percent of the general population, with a much higher occurrence in prisoners – roughly 1/3 of all inmates, and 10 – 15% of substance abuse users, with higher reports of men in both of these categories (Kiehl, 2006). Both psychopathy and alexithymia are hard to study due their broad, complex natures; for example, emotional dysregulation is difficult to define due to the fact that no assessment can properly capture every aspect of emotional regulation processes, behaviours, and neuroscience behind the dysfunction, yet we use it as a defining marker of both of these disorders. Recently, researchers have been attempting to understand the neurobiological underpinnings of both disorders, and how the disorders may be connected. In both disorders, abnormal brain regions have been indicated within the limbic system, the network responsible for emotional regulation and arousal of the body (Juarez, Kiehl, & Calhoun, 2013). Within the limbic system, dysfunction in areas such as the amygdala, anterior cingulate cortex (ACC), and insula have been identified as contributors to both alexithymia and psychopathy due to their relationship with emotional processing (Blair, 2008, Reker et al., 2010). Using previous knowledge, we can examine the brain regions of the amygdala, anterior cingulate cortex, and the insula in relation to emotional dysregulation, and attempt to find similarities between those who suffer with alexithymia or psychopathy. 

Characteristics of Alexithymia 

Alexithymia is a disorder that ranges on a spectrum, from low to high severity. The core characteristics of alexithymia include emotional dysregulation, interpersonal relationship complications, and antisocial behaviours (Salminen et al., 1999). Within these categories, symptoms of alexithymia can include limited imaginal capacity, struggles distinguishing bodily arousal from emotional arousal, lack of empathy and understanding, violent outbursts, problems forging relationships, and apathy (Lumley et al., 2007). Another defining characteristic of alexithymia is the autonomic nervous system dysfunction that occurs. Researchers suggest that due to the inability of individuals with alexithymia to express or verbalize their emotions effectively, they manifest them in physical symptoms. Common symptoms include stomach pain, racing heart, hyperhidrosis, sweaty hands, numbness of limbs, and chest pain (Mehling & Krause, 2005). Although controversial, recent research has suggested there are 2 subtypes of alexithymia. Type 1 alexithymia refers to classic alexithymia and is diagnosed in individuals who display little and are unaware of their emotions, and who have a strong external orientation in their thinking. On the other hand, type 2 alexithymia refers to individuals who experience more negative emotions and have difficulty interpreting their feelings, who tend to act confused and overwhelmed, and who display more outburst (Lumley et al., 2007). However, there is a lack of research on these two subscales, leaving these subtypes to be predominately hypothetical, with implications for future research. 

The severity of alexithymia can be identified using the Toronto Alexithymia scale (TAS) 20. The TAS-20 is a self-report questionnaire that asks 20 questions with relation to all 3 subdivisions of alexithymia: difficulty identifying feelings, difficulty expressing feelings, and strong external orientation in thinking (Taylor, Bagby, & Parker, 2003). Each of these factors have been correlated to different personality traits, with difficulty identifying feelings being linked to neuroticism, difficulty describing feelings linked to introversion, and strong external orientation in thinking linked to low openness (Lumley et al., 2007). These correlations between the alexithymia factors and personality traits may help explain different symptoms that alexithymics experience. Using results from the TAS-20 can indicate the severity of alexithymia, in which category an individual struggles with most, and the best course of action moving forward for someone that is alexithymic. Typically, men rank higher on difficulty expressing feelings and external orientation than women (Salminen et al., 1999). However, regardless of sex, as an individual ages, they tend to score higher on alexithymia scales – this is explained through the theory that as an individual ages, their neurons begin to deteriorate, leading to less connectivity and mass in critical areas, such as the limbic system (Salminen et al., 1999). Another aspect of alexithymia is poor response to psychological treatment methods due to individuals with the disorder commonly having external orientated thinking, and inability to internally reflect and answer the broad “how are you feeling, what are you feeling?” types of questions therapists may use. Cognitive-behavioral techniques may be a potential form of alternative treatment for patients with alexithymia, working on changing behaviours instead of describing feelings or expressing themselves (Sifneos, 1983). 

Characteristics of Psychopathy

According to DSM-5, psychopathy is not recognized as a mental disorder on its own, but as a specifier of Antisocial Personality Disorder (ASPD). Within the branch of ASPD, psychopathy is defined as a psychiatric disorder consisting of 3 main components: emotional deficits, antisocial behaviour, and pathological lying (Yang & Raine, 2008). A lack of strong emotions is considered to be one of the most defining aspects of psychopathy - emotional deficits encompass various behaviours, including lack of empathy and guilt, little to no anxiety or fear, remorselessness, and shallow affect (Yang & Raine, 2008). Research suggests a link between emotional dysfunction and genetics in psychopathy, with potential environmental factors such as trauma and neglect determining the way psychopathy manifests within individuals (Blair, 2008). Antisocial behaviour refers to an individual’s social deviancy and to behaviours such as impulsivity, irresponsibility, poor behavioral control, and criminality (Yang & Raine, 2008). Psychopaths typically have no reservations about disobeying rules, whether it’s breaking laws or smaller rules, and are known for their outbreaks of violent, aggressive behaviours. Finally, pathological lying is accompanied by psychopaths’ willingness and ease at which they tell lies, with no regard for their actions (Yang & Raine, 2008).

In order to determine if someone qualifies as a psychopath, the most common method used is the Psychopathy Checklist – Revised (PCL-R). PCL-R is an interview and review based diagnostic tool – patients institutional records are assessed, and a structed interview process is completed to determine things such as patient adjustments, criminal activity, etc. over time (Kiehl, 2006). This type of tool is often effective due to psychopaths’ tendency to lie on self-report measures. The PCL-R has 2 factors: factor 1 focuses on emotional and interpersonal features, such as charm and manipulativeness, while factor 2 looks at impulsive and antisocial behaviours (Edens et al., 1999). Psychopathy can be divided into 2 subdivisions, with type 1 psychopathy related to factor 1, and type 2 being related to factor 2. Type 1 psychopathy is characterized by lack of empathy, callousness, and lack of fear, and has been theorized to be linked to genetics and environmental factors growing up. Individuals with type 2 psychopathy are thought to feel emotions such as guilt and remorse but rank higher on impulsivity and poor behaviours in relation to criminality and violence (Lander, Lutz-Zois, Rye, & Goodnight, 2012). Although the PCL-R checklist is not designed to make distinctions between these subdivisions, different subdivisions of psychopathy lead to different neural defects which need to be evaluated more in depth to understand the basis of this disorder (Lander et al., 2012).

Neurobiology of Alexithymia and Psychopathy 

Alexithymia and psychopathy share multiple traits, with one of the most egregious being emotional dysfunction. No research has yet to connect the dots between the neurobiology of alexithymia and psychopaths even though they are commonly found to be comorbid with one another. A key area in emotional regulation is the limbic system, which is known to play a crucial role in emotional processing and regulation. Looking at the amygdala within the limbic system, it is thought to be involved in perceptions and processing of negative emotions, specifically fear, anger, and sadness (Blair, 2008). There are two subdivisions to the amygdala: the basolateral nuclei and the central nuclei. Research has shown that the basolateral nuclei is responsible for controlling the central nucleus, as well as transmitting information to the ventromedial prefrontal cortex (Blair, 2008). The ventromedial prefrontal cortex (vmPFC) is thought to play a large role in emotional regulation and mood disorders, a key component to both disorders (Blair, 2008). The anterior cingulate cortex (ACC) is a structure within the limbic system that is typically divided into 2 distinct regions, the rostral and the caudal region. The rostral region, known as the affective division, is involved in pain perception and affect regulation. This area is also thought to receive emotional information from the amygdala, with abilities to suppress emotional processing (Blair, 2008). The caudal region, known as the cognitive division, is involved in response conflict, error monitoring and emotional regulation within the autonomic nervous system (Kiehl et al., 2001). When lesions occur in the ACC, they tend to lead to things such as irresponsibility, hostility, and emotional unconcern (Laricchiuta et al., 2015). Finally, the insula is known to play a role in self-awareness, interception, subjective emotional experiences, addiction, and a slew of social emotions, such as lust and embarrassment (Uddin, Nomi, Hébert-Seropian, Ghaziri, & Boucher, 2017). In monkeys, after white matter degeneration due to insula ablation, it was found that the tracts were connected with the frontal lobe, along with the amygdala, cingulate cortex, and hippocampus (Uddin et al., 2017). When the insula is damaged, it can lead to symptoms such as altered emotional experiences and apathy (Uddin et al., 2017). All 3 of these regions – the amygdala, the ACC, and the insula – play crucial roles in the emotional processing of individuals with the disorders alexithymia and psychopathy.  

In a study done by Laricchiuta et al. (2015), researchers looked at neurobiological volumes in relation to alexithymia. 60 participants completed the TAS-20 and MRI scans in a special MRI that allowed researchers to look at the white matter and gray matter in participants’ brains. The researchers found that areas in the limbic system, such as the amygdala, parahippocampal gyrus, and the insula were negatively associated with TAS-20 scores. The negative correlation between the right amygdala and TAS-20 was especially strong - stronger than between other areas of the brain. Firstly, the data confirmed the contribution of the limbic network in alexithymic traits, especially for those who ranked higher on the alexithymic spectrum (Laricchiuta et al., 2015). Secondly, the data suggests that decreased amygdala and insula volume in the limbic system contributes to the emotional dysregulation seen in alexithymia (Laricchiuta et al., 2015). They also found there was no significant association found between the ACC and TAS-20 scores, which is contradictory to other researchers’ findings. In a study by Paradiso et al. (2008), which used MRI and various psychological scales, researchers found that gray matter volume decreased as participant age increased, specifically in the rostral and dorsal anterior cingulate cortex regions. Furthermore, they specifically found that higher alexithymia scores were also correlated to lower right rostral ACC volume, and that the correlation was mainly influenced by factor 3 – strong external orientated thinking (Paradiso et al., 2008). 

Reker et al. (2010) found similar results, in a study where they used fMRI to look at automatic, involuntary reactivity in the brain in response to pictures of sad and happy faces. The data showed that there was an inverse correlation between left amygdala, parahippocampal gyrus, and bilateral insula and TAS-20 total scores, after controlling for depression and anxiety. In addition, the subscale difficulty describing feelings and the subscale difficulty identifying feelings were inversely related to left amygdala activation for sad faces. This study indicates that the higher on the alexithymia scale, the less automatic brain activity that is occurring in areas responsible for emotional processing and identification, which backs up the research found by Laricchiuta et al. (2015). Both studies have shown significant amygdala impairment, however, on different sides of the brain. Reker et al. (2010) suggests that, in general, neuroimaging studies have shown low responsivity of the amygdala to emotional stimuli on both sides of the brain, which may be due to low interconnectivity of the hemisphere or the amygdala to other areas of the brain. 

In regard to psychopaths, a study completed by Birbaumer et al. (2005) used a classic aversive differential delay conditioning while performing neuroimaging. The results found suggest that healthy controls had significant activation in their frontolimbic circuit, while psychopaths had no significant changes in this area of the brain when presented with fear invoking stimuli. There was significantly less activation in the amygdala, middle and right interior insula, and anterior cingulate cortex of the psychopaths, along with no change in skin conductance or emotional valence ratings (Birbaumer et al., 2005). These results suggest a lack of emotional processing and autonomic regulation in psychopaths, similar to individuals who experience frontolimbic lesions (Birbaumer et al., 2005). These results are similar to the emotion deficits found in the frontolimbic circuit in the study by Laricchiuta et al. with alexithymia. Another study focused on the neuroanatomy was Boccardi et al. (2011), where researchers created individual brain masks for each hemisphere for each participant, comparing psychopaths and controls. Interestingly, they found that global volume of the amygdala was significantly greater in offenders than it was in healthy controls, by almost 30% tissue difference. It was suggested that this difference was potentially due to the fact that psychopaths tend to have higher IQs while the IQs of their sample population were on the lower side of normal. They also found tissue differences in the anterior cingulate cortex and parahippocampus, both of which were significantly reduced in psychopaths compared to healthy controls. 

Finally, in Kiehl et al. (2001), fMRI was used to elucidate the neurobiological differences in criminal psychopaths vs. criminal non-psychopaths and noncriminal controls while performing a memory task. The fMRI data showed that in criminal psychopaths there was less affect-related activity in the caudal anterior cingulate and right amygdala, compared to both controls, along with less affect related activity in the left amygdala and the parahippocampal gyrus compared to non-criminals. Also, there was no differences between all 3 groups when neutral stimuli were presented, which suggests that the psychopaths only differ when it comes to emotional processing, which is affected by all the aforementioned areas. 

Connecting circuits: Alexithymia & Psychopathy in relation to Emotional Dysregulation 

Combining all the previous research, multiple themes start to emerge from the data. First, both psychopaths and alexithymics have decreased brain activation in regard to emotional stimuli, specifically in the amygdala, anterior cingulate cortex, and insula. In most studies, there is also an agreeance that volumes of these specific areas have decreased.   This seems to suggest that there could be a potential neural circuitry deficit within the limbic system, with lack of connectivity between all the structures, in both alexithymics and psychopaths. These deficits could account for the similarities in emotional dysregulation in both disorders, while other areas of the brain account for different symptoms they encounter. Another theme that emerged was the deficits in the prefrontal cortex in relation to the amygdala – more research focusing on the prefrontal cortex in relation to signals from the limbic system should be completed in order to better understand the relationship between the disorders. Interestingly, the research has shown that people with alexithymia tend to manifest their emotions and processing in physical symptoms, while for psychopaths, there is a lack of autonomic nervous system (ANS) reactivity. The ANS is typically controlled by the hippocampus, which receives multiple inputs from emotional processing in the limbic system. In the study completed by Boccardi et al., an increased amygdala volume for psychopaths compared to normal controls was found. Although more neuroimaging would need to be performed to come to an accurate conclusion, it seems possible that increased amygdala volume could mediate signals being sent to the hippocampus, which in turn would affect the ANS. In alexithymics, their decreased amygdala size could be an indicator of how they do not process their emotions as easily, and projects to the ANS, leading to a manifestation of physical symptoms. 

A mutual characteristic between psychopathy and alexithymia is the lack of clinical treatment options – no forms of therapy have been successful in “curing” either psychopathy or alexithymia. Maladaptive behaviours, such as drug abuse and violence are also highly correlated with both disorders, which may be due to the fact that there is no type of treatment or method to help those living with the disorders. In multiple of the studies above, a large limitation was that the participants had previous history of drug or alcohol abuse. The insula is known to play a large role in addiction and had been seen to have decreased activity in both psychopaths and alexithymics. This dysregulation of the insula may not only influence the emotions of psychopaths and alexithymics, but also their addictive personalities. This possibility could be looked at further in other studies.

Conclusion

Ultimately, looking at the neurobiological underpinnings of two psychiatric disorders is a complex problem. Research has shown the similarities between psychopathy and alexithymia in that both involve malfunctions in the amygdala, anterior cingulate cortex, and insula. Deficits in these areas help to explain the symptomology that both psychopaths and alexithymics express. Although this paper can provide important insights into these disorders, there are a few limitations to the data used that must be presented – firstly, a large amount of the data that was documented in this review was from small samples of prison populations, as there is a larger prevalence of psychopaths and alexithymics in prison, which allowed for them to be identified more easily. Secondly, for both psychopathy and alexithymia, patients were looked at on a broad basis, and they were not dived into the potential subtypes that have been proposed in recent years. For example, in psychopaths, there is a term called “successful psychopaths” which refers to a specific subset of psychopaths who avoid confinement in prison, rehab, etc. This subgroup of psychopaths suggests that although this research is being done, brain abnormalities may be different for each type of subdivision of psychopathy, and that the results being found may not be generalizable to all incidences of psychopathy (Yang & Raine, 2008). A third limitation is the types of disorders that are being studied – both alexithymia and psychopathy are comorbid with various other disorders, and it is hard to determine what symptom is due to what disorder, or elucidate each disorder’s symptoms separately. For example, more than 30% of the time, people who suffer from alexithymia also suffer from depression, with depressed men commonly being more alexithymic than women (Honkalampi et al., 2000). Depression studies have shown the ability of depression to change the brains, especially in areas that deal with emotional processing. 

Future studies should aim to look at larger samples of the population, potentially outside of the prison system if they are able to find participants. They should also use more in depth neurological imaging in relation to distinct subtypes of both alexithymia and psychopathy. More development of the psychological measures would need to be crafted to do a further analysis between the two disorders. Further research needs to also include more models of sex in relation to brain activity, as differences between sexes have been found for both psychopathy and alexithymia. Overall, further in-depth neurological analyses would allow for better insight into the criminal world, as well as allow for improved forms of treatment targets, therapies, and other clinical uses. 

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