Current Psychiatry Reviews - Volume 13, Issue 2, 2017

The term Theory of Mind (ToM) has been used to refer to the ability of an individual to make inferences about what others may be thinking or feeling and to predict what they may do in a given situation based on those inferences—in other words, the ability to take another person’s perspective. Unfortunately, most researchers talk about ToM as if it were a cognitive process, which, if true, means that it can never be studied directly. As a result, various tests of behavior have been devised from which ToM (or the lack thereof) is deduced. As with all cognitive processes, inferring ToM based solely on observed behavior is problematic because there is no direct and independent evidence of the ToM. And, because ToM itself is not directly observable, the question remains as to how one might teach it to individuals diagnosed with psychological disorders who have ToM deficits. In the present essay, I argue that it is more parsimonious and ultimately more practical to view ToM as only a label for a set of observed behaviors that are acquired according to relatively straightforward principles of learning and, thus, also capable of being taught to individuals diagnosed with psychological disorders who lack such behaviors.

Although aggressive behaviours, and especially bullying, are regarded as socially undesirable, there is controversy as to whether they are also evidence of deficits on measures of social skills or social competence. Many measures of emotional intelligence and social competence include aspects of social desirability. However, theory of mind skills are neutral as regards social desirability and can be used for prosocial or antisocial ends. It has been proposed that children who bully others at school, especially ringleader bullies, may actually have and use good theory of mind skills. Nine studies were found that directly examined theory of mind in relation to roles involved in bullying in childhood. Of these, five found some positive association of theory of mind with bullying behaviors. In addition, some associations were found with defending behaviors, and negative associations with being a victim of bullying. These associations have been found to interact, in one or more studies, with type of bully, type of aggression, age, gender, and individual characteristics such as levels of narcissism and levels of victimization experience. Although the research base is limited, the evidence does support the view that theory of mind skills can be used for both prosocial (e.g. defending) and antisocial (e.g. bullying) ends, whereas it is the victims of bullying who may be more likely to be deficient in such skills.

Empathy is one of the essential attributes underlying social interactions. Empathic skills have been associated with an ability to accurately recognise facial emotions. Importantly, both lack and excess of empathy have been related to suboptimal mental health. Empathy deficits have been found to underlie social interaction difficulties in Autism Spectrum Disorder and Personality disorder. On the other hand, it has been shown that the individuals with high empathy may become vulnerable to emotional burnout. In particular, empathic distress has been described in mental health professionals and carers. The question arises – are the findings of empathic distress in caregivers pertinent to the vulnerability to emotional disorders in general? In this review, we will consider current models of empathy and discuss potential links between characteristics of empathy and emotion processing that may be relevant to mental health.

Theory of mind deficit is a core feature of schizophrenia and is considered a vulnerability marker of the disorder. The majority of studies measuring theory of mind in schizophrenia involve multiple-episode or chronic schizophrenia patients, and therefore it is important to delineate whether these deficits occur before or following illness-onset by assessing high-risk subjects (clinical high risk and ultra-high risk), early-onset psychosis, and first-degree relatives. We address the question of whether theory of mind impairment is specific or a facet of general cognitive impairment in these clinical populations, and incorporate genetic and neuroimaging studies on the theory of mind. The review provides a succinct evaluation of the literature, discusses current limitations and proposes future directions.

This paper describes an animal (rat) model for the study of Bipolar Disorder (BD) in humans. The paper presents research, previously unpublished, conducted over more than 25 years. The model is derived from a natural genetic variant discovered in the rat population; these rats having been all brothers and sisters (littermates) from a single litter that was observed to be hyperactive in the home cage. The original animals were first inbred and then the offsprings were selectively-bred for more than 50 generations; this line of rats that proved to be a model for BD was named the Hyperactive (HYPER) rat. Findings presented here indicate that this rat model shows similarity to human BD with respect to the four criteria used to judge/validate any animal model of a human psychological/ psychiatric disorder: (1) etiology, (2) symptomatology, (3) underlying pathophysiology, and (4) responsiveness to treatments that are effective for the human disorder. To summarize, HYPER rats mimic manic behavior by showing an outburst of extreme hyperactivity that lasts for several days after being exposed to a stressor, and also can show pronounced and prolonged post-stress depression of home-cage activity; moreover, critical for modeling BD, HYPER rats assessed for 2-4 months show “cycling” between manic-like outbursts and depression. (Note: prolonged depression occurs in HYPER rats after a single acute stressor event and therefore represents the first rat model to meet the DSM criterion for appropriate duration of depressive symptoms [persisting for more than 14 days] following a discrete precipitating event). The HYPER rat also manifests other characteristics seen in human BD – high levels of anxiety, a hyper-responsive pituitary-adrenal axis, elevated consumption of alcohol, anhedonia (indicated by reduced propensity to consume highly palatable sucrose solutions), cognitive differences from normal animals, abnormal midbrain dopaminergic transmission, and skin lesions that point to genetic similarity to humans with BD. Finally, the behavioral abnormalities of HYPER rats that mimic BD also respond to drugs used in the treatment of BD in humans; their manic-like outburst of extreme hyperactivity when exposed to stress is blocked by treatment with lithium or valproate. Lithium treatment also reduces “cycling” of HYPER rats that results in fewer cycles and less severe cycling. The HYPER rat model shows the most extensive list of similarities to human BD reported to date. Insofar as this model was not produced experimentally but instead arose as a natural genetic variant, thereby reproducing human BD in this important respect, this would seem to add considerably to its attraction as a model of BD. The promise of the HYPER rat is that it embodies critical aspects of human BD in a rodent. A Summary Table listing all phenomena observed in the HYPER rat relevant to human BD can be found near the conclusion of this article. In view of the behavioral similarities shown by the HYPER rat to critical behavioral characteristics of BD in humans, the HYPER rat would seem extremely useful as a means to test/screen potential new treatments for BD. Additionally, apparent similarities of pathophysiology and indications of similar genetics of the HYPER rat to human BD supports its study to look for underlying causes of BD, and also its use in genetic investigations where it can be employed using some of the latest techniques, such as transcriptomics and RNA-Seq analysis, that are presently not possible in humans.