Thought blocking

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Thought blocking is a medical or psychological phenomenon in which a person is talking about a particular subject and then abruptly changes to another subject. Thought blocking is a type of thought disorder associated with disrupted speech processes.


When thought blocking, people may express themselves in a manner that is not understandable to others. They may repeat words involuntarily or make up new words. When doctors diagnose thought blocking they consider a variety of causes, such as schizophrenia, anxiety, petit mal seizures, dissociation, bradyphrenia, aphasia, dementia or delirium. [1]


Thought blocking occurs most often in people with psychiatric illnesses, most commonly schizophrenia. [2] A person's speech is suddenly interrupted by silences that may last a few seconds to a minute or longer. [3] [4] When the person begins speaking again, after the block, they will often speak about an unrelated subject. Blocking is also described as an experience of unanticipated, quick and total emptying of the mind. [5] People with schizophrenia commonly experience thought blocking and may interpret the experience in peculiar ways. [5] For example, a person with schizophrenia might remark that another person has removed their thoughts from their brain. [5]

When evaluating a patient for schizophrenia, a physician may look for thought blocking. [6] In schizophrenia, patients experience two types of symptoms: positive and negative. Positive symptoms include behavior added on to a person's daily functioning. For instance, delusions, hallucinations, disorganized speech, disorganized behavior and thought are all positive symptoms. In contrast, negative symptoms are characterized by missing parts of the average individual's persona, including flat affect, apathy, speaking very little, not finding enjoyment in any activity, and not attending to basic acts of daily living (ADLs), such as bathing, eating, and wearing clean clothes.


Generalized anxiety disorder (GAD) is defined as excessive worry about matters in two or more separate subjects for at least six months. [7] When a person experiences an anxiety attack, they may become so hyperfocused on the distressing stimuli and/or overwhelmed with the situation that regular speech is difficult for that person to produce. The thought blocking that occurs in this instance is usually short lived because anxiety attacks are transient. After an episode occurs, a person is typically able to resume their normal way of speaking.


Thought blocking is associated with petit mal seizure. As such, it can be hard for people to organize their speech, resulting in thought blocking. [8]

Dissociation and Post-traumatic stress disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a psychiatric disorder that can occur after a person experiences a traumatic, upsetting event and develops inappropriate strategies to cope. [9] These maladaptive approaches can include, but are not limited to, dissociative symptoms: depersonalization and derealization. When these dissociative symptoms surface, they can be extremely intrusive and result in a person not being able to focus on their diction, or manner of speaking, and result in thought blocking. People with PTSD may find that blocking of thought occurs more often if they have not addressed the source of their PTSD.

Cognitive & Motor Disorders

In the elderly, blocking of thought can be a feature of several cognitive and motor disorders, including underlying dementia and delirium. It is common that as a person ages, they may become forgetful and/or lose their train of thought. When it becomes more persistent and affects one's ability to carry out their ADLs, a major neurocognitive disorder like dementia is among the possible causes. [10] In addition, thought blocking can occur in patients with parkinsonism, a disorder that features slowing of movement, muscle rigidity, and impairment. The distinguishing feature between parkinsonism and Parkinson's disease is that the causes of parkinsonism are numerous, including drugs, toxins, metabolic disorders, and head trauma. [11] Furthermore, a stroke can result in a disordered speech process such as thought blocking. [1] When a stroke affects an artery called the middle cerebral artery (MCA), it can result in damage to an area of the brain responsible for speech. As such, people can understand well but have problems saying the words they want to, or be able to speak but have nonsensical word content. These symptoms are referred to as aphasias, and aphasias can present with thought blocking. [1]

Related Research Articles

Psychosis Condition of the mind that involves a loss of contact with reality

Psychosis is an abnormal condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations. Other symptoms may include incoherent speech and behavior that is inappropriate for the situation. There may also be sleep problems, social withdrawal, lack of motivation, and difficulties carrying out daily activities. Psychosis can have serious outcomes.

Dissociative identity disorder Mental illness characterized by alternating between multiple personality states and memory loss

Dissociative identity disorder (DID), previously known as multiple personality disorder (MPD), is a mental disorder characterized by the maintenance of at least two distinct and relatively enduring personality states. The disorder is accompanied by memory gaps beyond what would be explained by ordinary forgetfulness. The personality states alternately show in a person's behavior; however, presentations of the disorder vary. Other conditions that often occur in people with DID include post-traumatic stress disorder, personality disorders, depression, substance use disorders, conversion disorder, somatic symptom disorder, eating disorders, obsessive–compulsive disorder, and sleep disorders. Self-harm, non-epileptic seizures, flashbacks with amnesia for content of flashbacks, anxiety disorders, and suicidality are also common.

A communication disorder is any disorder that affects an individual's ability to comprehend, detect, or apply language and speech to engage in discourse effectively with others. The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language.

Schizoaffective disorder is a mental disorder characterized by abnormal thought processes and an unstable mood. The diagnosis is made when the person has symptoms of both schizophrenia and a mood disorder—either bipolar disorder or depression—but does not meet the diagnostic criteria for schizophrenia or a mood disorder individually. The main criterion for the schizoaffective disorder diagnosis is the presence of psychotic symptoms for at least two weeks without any mood symptoms present. Schizoaffective disorder can often be misdiagnosed when the correct diagnosis may be psychotic depression, psychotic bipolar disorder, schizophreniform disorder, or schizophrenia. It is imperative for providers to accurately diagnose patients, as treatment and prognosis differs greatly for each of these diagnoses.

Anhedonia is a diverse array of deficits in hedonic function, including reduced motivation or ability to experience pleasure. While earlier definitions of anhedonia emphasized the inability to experience pleasure, anhedonia is used by researchers to refer to reduced motivation, reduced anticipatory pleasure (wanting), reduced consummatory pleasure (liking), and deficits in reinforcement learning. In the DSM-5, anhedonia is a component of depressive disorders, substance-related disorders, psychotic disorders, and personality disorders, where it is defined by either a reduced ability to experience pleasure, or a diminished interest in engaging in pleasurable activities. While the ICD-10 does not explicitly mention anhedonia, the depressive symptom analogous to anhedonia as described in the DSM-V is a loss of interest or pleasure.

Thought disorder Disorder of thought form, content or stream

A thought disorder (TD) is any disturbance in cognition that adversely affects language and thought content, and thereby communication. A variety of thought disorders were said to be characteristic of people with schizophrenia. A content-thought disorder is typically characterised by the experience of multiple delusional fragments. The term, thought disorder, is often used to refer to a formal thought disorder.

In psychology, alogia is poor thinking inferred from speech and language usage. There may be a general lack of additional, unprompted content seen in normal speech, so replies to questions may be brief and concrete, with less spontaneous speech. This is termed poverty of speech or laconic speech. The amount of speech may be normal but conveys little information because it is vague, empty, stereotyped, overconcrete, overabstract, or repetitive. This is termed poverty of content or poverty of content of speech. Under Scale for the Assessment of Negative Symptoms used in clinical research, thought blocking is considered a part of alogia, and so is increased latency in response.

Depersonalization can consist of a detachment within the self, regarding one's mind or body, or being a detached observer of oneself. Subjects feel they have changed and that the world has become vague, dreamlike, less real, lacking in significance or being outside reality while looking in. Chronic depersonalization refers to depersonalization/derealization disorder, which is classified by the DSM-5 as a dissociative disorder, based on the findings that depersonalization and derealization are prevalent in other dissociative disorders including dissociative identity disorder.

Dissociation, as a concept that has been developed over time, is any of a wide array of experiences, ranging from a mild emotional detachment from the immediate surroundings, to a more severe disconnection from physical and emotional experiences. The major characteristic of all dissociative phenomena involves a detachment from reality, rather than a loss of reality as in psychosis.

Nightmare disorder

Nightmare disorder, also known as dream anxiety disorder, is a sleep disorder characterized by frequent nightmares. The nightmares, which often portray the individual in a situation that jeopardizes their life or personal safety, usually occur during the REM stages of sleep. Though most people have experienced at least one nightmare during their life, subjects with nightmare disorder experience them with a greater frequency. The disorder's DSM-IV number is 307.47.

Mental status examination Way of observing and describing a patients current state of mind

The mental status examination (MSE) is an important part of the clinical assessment process in neurological and psychiatric practice. It is a structured way of observing and describing a patient's psychological functioning at a given point in time, under the domains of appearance, attitude, behavior, mood, and affect, speech, thought process, thought content, perception, cognition, insight, and judgment. There are some minor variations in the subdivision of the MSE and the sequence and names of MSE domains.

Depersonalization-derealization disorder Human mental dissociative disorder

Depersonalization-derealization disorder, is a mental disorder in which the person has persistent or recurrent feelings of depersonalization or derealization. Depersonalization is described as feeling disconnected or detached from one's self. Individuals may report feeling as if they are an outside observer of their own thoughts or body, and often report feeling a loss of control over their thoughts or actions. Derealization is described as detachment from one's surroundings. Individuals experiencing derealization may report perceiving the world around them as foggy, dreamlike/surreal, or visually distorted.

Dissociative disorders (DD) are conditions that involve disruptions or breakdowns of memory, awareness, identity, or perception. People with dissociative disorders use dissociation as a defense mechanism, pathologically and involuntarily. The individual suffers these dissociations to protect themselves. Some dissociative disorders are triggered by psychological trauma, but depersonalization-derealization disorder may be preceded only by stress, psychoactive substances, or no identifiable trigger at all.

This glossary covers terms found in the psychiatric literature; the word origins are primarily Greek, but there are also Latin, French, German, and English terms. Many of these terms refer to expressions dating from the early days of psychiatry in Europe.

Multiple complex developmental disorder (MCDD) is a research category, proposed to involve several neurological and psychological symptoms where at least some symptoms are first noticed during early childhood and persist throughout life. It was originally suggested to be a subtype of autistic spectrum disorders (PDD) with co-morbid schizophrenia or another psychotic disorder; however, there is some controversy that not everyone with MCDD meets criteria for both PDD and psychosis. The term multiplex developmental disorder was coined by Donald J. Cohen in 1986.

Derealization is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring, and depth. It is a dissociative symptom that may appear in moments of severe stress.

Childhood schizophrenia is essentially the same in characteristics as schizophrenia that develops at a later age, but has an onset before the age of 13, and is more difficult to diagnose. Schizophrenia is characterized by positive symptoms that can include hallucinations, delusions, and disorganized speech; negative symptoms, such as blunted affect and avolition and apathy, and a number of cognitive impairments. Differential diagnosis is problematic since several other neurodevelopmental disorders, including autism-spectrum disorder, language disorder, and attention deficit hyperactivity disorder, also have signs and symptoms similar to childhood-onset schizophrenia.

Tangential speech or tangentiality is a communication disorder in which the train of thought of the speaker wanders and shows a lack of focus, never returning to the initial topic of the conversation. It tends to occur in situations where a person is experiencing high anxiety, as a manifestation of the psychosis known as schizophrenia, in dementia or in states of delirium. It is less severe than logorrhea and may be associated with the middle stage in dementia. It is, however, more severe than circumstantial speech in which the speaker wanders, but eventually returns to the topic.


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