Tourette syndrome (TS) is a neurodevelopmental disorder that causes involuntary muscle and vocal tics. These tics usually begin in childhood and continue into adulthood, sometimes accompanied by other psychiatric disorders such as attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, depression, etc. The cause of TS is unknown, but it may be related to abnormalities in genetics, environment, immune system, and brain structure and function. So what are the characteristics of TS in the neuropsychological dimension.
Cognitive characteristics of patients with TS.
The cognitive abilities of patients with TS are usually within the normal range, but there are some specific deficits, mainly related to executive function, working memory, attention, and flexibility.
Executive function: refers to people's ability to plan, organize, control, and supervise their own behavior, and it includes sub-components such as inhibition, transformation, renewal, and interference control. Patients with TS show deficiencies in all aspects of executive function, especially in inhibition and conversion. This may be related to tics, as these movements require suppression of inappropriate impulses and switching to different tasks.
Working memory: refers to the ability of people to temporarily store and manipulate information, which is essential for complex cognitive activities. Patients with TS have deficits in working memory, particularly visuospatial working memory. Distraction and motor tics in patients with TS can interfere with the encoding and maintenance of visual information.
Attention: refers to the ability of people to choose and maintain attention to certain stimuli or tasks, and it includes subcomponents such as selective attention, sustained attention, distracted attention, and conversion attention. Patients with TS also show deficiencies in attention, especially in selective and sustained attention. This may be related to tic interference in patients with TS, which can be distracting and resource-consuming.
Flexibility: refers to people's ability to adjust their thinking or behavior according to changes in the environment or goals, and it includes two aspects: cognitive flexibility and behavioral flexibility. Patients with TS also have deficiencies in flexibility, especially in cognitive flexibility. This may be related to stereotyped and obsessive thinking and behavior patterns in patients with TS.
Cognitive features may be related to the connections of the prefrontal lobe, basal ganglia, and cerebral cortex of the brain.
The prefrontal lobe is an important region of the brain that is involved in cognitive processes such as executive function, working memory, attention, and flexibility. The basal ganglia forms a circuit with the prefrontal lobe that regulates functions such as movement, mood, and cognition. The cerebral cortex is the outermost layer of the brain, and it is made up of different regions that are responsible for different sensory, motor, and higher cognitive functions. Patients with TS may have abnormalities in the connections between the prefrontal lobe, basal ganglia, and cerebral cortex, resulting in cognitive impairment. These abnormalities may be related to an imbalance of neurotransmitters, especially too much or too little dopamine. Dopamine is an important neurotransmitter that plays a role in the brain that regulates functions such as reward, motivation, learning, Xi and memory. Dopamine levels in patients with TS may be too high or too low, affecting signal transmission between the prefrontal lobe, basal ganglia, and cerebral cortex, thereby affecting cognitive function.
Emotional characteristics of patients with TS.
The emotional state of people with TS is often affected by tics, which leads to negative emotions such as anxiety, depression, anger, and low self-esteem. These negative emotions may exacerbate the symptoms of TS, creating a vicious cycle. People with TS have impaired ability to regulate their emotions, making it difficult for them to control and express their emotions, or to overreact and lack reactions. People with TS are also affected in their ability to recognize emotions, making it difficult for them to understand and recognize the emotions of others, or to misinterpret and ignore the emotions of others.
Emotional traits in patients with TS may be related to the connections of the amygdala, cingulate gyrus, and prefrontal lobes of the brain.
The amygdala, also known as the amygdala, is located above the anterior end of the inferior corner of the lateral ventricle, lateral to the parahippocampal sulcus, and the top is connected to the end of the caudate nucleus. The amygdala is the subcortical center of the limbic system, which has the function of regulating visceral activity and producing emotions. Trigger an emergency response so that animals can stand up or flee from danger. This amygdala can generate emotional incentives through an emergency response, which enhances memory. The amygdala is involved in processes such as the generation, recognition, and regulation of emotions in brain function.
Cingulate gyrus: It is the gyrus located between the cingulate sulcus and the groove of the corpus callosum on the medial surface of the cerebral hemisphere, and belongs to the cortical part of the limbic system. The cingulate gyrus contains a large number of nerve fibers inside, and its gray matter cortex is called the cingulate cortex. The cingulate gyrus is part of the limbic lobe of the limbic system of the brain and its functions are involved in emotion, Xi, and memory. The cingulate gyrus is the brain's involvement in processes such as monitoring, evaluating, and integrating emotions.
In patients with TS, there may be abnormalities in the connection between the amygdala, cingulate gyrus, and prefrontal lobes, resulting in impaired emotional function. These abnormalities may be related to an imbalance of neurotransmitters, particularly too little or too much serotonin. Serotonin is an important neurotransmitter that plays a role in the brain in regulating functions such as mood, sleep, appetite, and pain. Serotonin levels in patients with TS may be too low or too high, affecting signaling between the amygdala, cingulate gyrus, and prefrontal lobes, thus affecting emotional functioning.
Social characteristics of patients with TS.
The social competence of people with TS is often affected by tics, causing them to feel embarrassed, unconfident, isolated, or discriminated against in social situations. These social dilemmas can exacerbate the symptoms of TS, creating a vicious cycle. Approximately 50% of children with TS have social dysfunction, and co-occurring conditions such as ADHD and anxiety may further exacerbate these social difficulties.
During clinical evaluation, children with TS lack social acceptance, lack of social self-esteem, and difficulty forming and maintaining friendships. Frequent movements and vocalizations can be perceived as strange or disruptive in social interactions. It is not uncommon to hear children being ridiculed at school for tics, or parents and children hearing disturbing comments in public places. The middle school years seem to be a risky time when children are particularly susceptible to being ridiculed or ostracized by their peers for their obvious tics. In the long run, this can lead to a lack of opportunities to develop social skills and friendships. Tic-related impairment has been observed to correlate with the severity of tics and tends to decrease with age. By adolescence, problems with awareness of social tics and social self-esteem become more prominent and may lead to avoidance of certain social situations.
Social characteristics in patients with TS may be related to the connections of the temporal lobe, amygdala, and prefrontal lobes of the brain.
The temporal lobe is one of the main lobes of the brain, located below the frontal and parietal lobes and anterior to the occipital lobe. The dorsal side of the temporal lobe is the lateral sulcus. It is involved in processes such as the processing of language and social information. Patients with TS may have abnormalities in the connections between the temporal lobe, amygdala, and prefrontal lobes, resulting in an imbalance of neurotransmitters, with too much or too little dopamine and serotonin secretion, affecting signaling between the temporal lobe, amygdala, and prefrontal lobe, and thus social functioning.
Behavioral characteristics of patients with TS.
The behaviour of patients with TS is often influenced by tics, causing them to develop impulsive, aggressive, self-injurious, or other maladaptive behaviors. These behaviors may cause more distress and risk to people with TS, affecting their quality of life. The ability of people with TS to regulate their behavior is also impaired, causing them to have difficulty inhibiting or controlling their behavior, overreacting, or lacking responsiveness.
The limbic portion of the cortico-subcortical circuit may be involved in the pathogenesis of Tourette syndrome. They are anatomically, developmentally, neurochemically, and functionally related to the basal ganglia, and it has been suggested that disorders of basal ganglia development produce tics, obsessive-compulsive disorder, and attention deficit hyperactivity disorder.
This was illustrated in a 2008 article in Arch Gen Psychiatry, "Morphological Characteristics of Children with Tourette Syndrome and ** Amygdala and Hippocampus", in which the investigators organized 282 subjects (154 patients with TS and 128 controls) and found that the overall volume of the hippocampus and amygdala in the TS group was significantly larger. The increase in volume in the TS group came mainly from the cephalic and medial surfaces of the hippocampus and the dorsal and ventral surfaces of the amygdala (beyond its basolateral and **nucleus). In the TS group, the volume of these subregions decreased with age, but not in the control group, so that the subregions were significantly larger in children with TS and significantly smaller in ** with TS compared to the control group. In children and **, the volume of these subregions was inversely correlated with the severity of symptoms of tics, obsessive-compulsive disorder, and ADHD, suggesting that the enlargement of these subregions may have compensatory and neuromodulatory effects on tic-related symptoms.
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