Palilalia (from the Greek πάλιν ("pálin") meaning "again" and λαλιά ("laliá") meaning "speech" or "to talk"), a complex tic, is a language disorder characterized by the involuntary repetition of syllables, words, or phrases. It has features resembling other complex tics such as echolalia or coprolalia, but, unlike other aphasias, palilalia is based upon contextually correct speech.

It was originally described by Alexandre-Achille Souques in a patient with stroke that resulted in left-side hemiplegia, although a condition described as auto-echolalia in 1899 by Édouard Brissaud may have been the same condition.

Palilalia is considered an aphasia, a disorder of language, and is not to be confused with speech disorders, as there is no difficulty in the formation of internal speech. Palilalia is similar to speech disorders such as stuttering or cluttering, as it tends to only express itself in spontaneous speech, such as answering basic questions, and not in automatic speech such as reading or singing; however, it distinctively affects words and phrases rather than syllables and sounds.

Palilalia may occur in conditions affecting the pre-frontal cortex or basal ganglia regions, either from physical trauma, neurodegenerative disorders, genetic disorders, or a loss of dopamine in these brain regions. Palilalia occurs most commonly in Tourette syndrome and may be present in neurodegenerative disorders like Alzheimer's disease and progressive supranuclear palsy.

Echolalia (also known as echologia or echophrasia) is defined as the unsolicited repetition of vocalizations made by another person (by the same person is called palilalia). In its profound form it is automatic and effortless. It is one of the echophenomena, closely related to echopraxia, the automatic repetition of movements made by another person; both are "subsets of imitative behavior" whereby sounds or actions are imitated "without explicit awareness". Echolalia may be an immediate reaction to a stimulus or may be delayed.

The word "echolalia" is derived from the Greek , meaning "echo" or "to repeat", and ("laliá") meaning "speech" or "talk" (of onomatopoeic origin, from the verb ("laléo"), meaning "to talk").

Echolalia can be categorized as immediate (occurring immediately after the stimulus) vs. delayed (some time after the occurrence of a stimulus). Immediate echolalia results from quick recall of information from the short-term memory and "superficial linguistic processing". A typical pediatric presentation of immediate echolalia might be as follows: a child is asked "Do you want dinner?"; the child echoes back "Do you want dinner?", followed by a pause, and then a response, "Yes. What's for dinner?"

In delayed echolalia the patient repeats words, phrases, or multiple sentences after a delay that can be anywhere from hours to years later. Immediate echolalia can be indicative that a developmental disorder exists, but this is not necessarily the case. Sometimes echolalia can be observed when an individual echoes back a statement to indicate they are contemplating a response and fully heard the original statement.

Researchers observed the daily repetitions of an autistic six-year-old in order to examine the differences between triggers for delayed versus immediate echolalia. Researchers further distinguished immediate echos by the sequential context in which they occur: after corrections, after directives, or in indiscernible sequential positions. Delayed echos are distinguished on the basis of ownership: self-echos, other-echos, and impersonal echos. The results showed that nearly all immediate echos produced by the six-year-old were found in sequential contexts, while the delayed echoes also occurred in the basis of ownership.

Although echolalia can be an impairment, the symptoms can involve a large selection of underlying meanings and behaviors across and within subjects. "Mitigated echolalia" refers to a repetition in which the original stimulus is somewhat altered, and "ambient echolalia" refers to the repetition (typically occurring in individuals with dementia) of environmental stimuli such as a television program running in the background.

Examples of mitigated echolalia are pronoun changes or syntax corrections. The first can be seen in the example of asking the patient “Where are you going?” and with patient responding “Where am I going?” The latter would be seen in the clinician asking “Where are I going?” and the patient repeating “Where am I going?” In mitigated echolalia some language processing is occurring. Mitigated echolalia can be seen in dyspraxia and aphasia of speech.

A Japanese case report describes a 20-year-old college student who was admitted to the hospital complaining about headaches and meningitis; however, he also exhibited signs of ambient echolalia. The researchers stated that the young patient's repetition was occurring at approximately the same tempo as his normal speech rate. The patient did not simply repeat words he had heard one after another. The patient reported that his ambient echolalia appeared to be random but appeared when he was distracted. He was also aware of his echolalia, but said he is unable to stop the repetitions.

Stuttering, also known as stammering, is a speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sounds, syllables, words or phrases as well as involuntary silent pauses or blocks in which the person who stutters is unable to produce sounds. The term "stuttering" is most commonly associated with involuntary sound repetition, but it also encompasses the abnormal hesitation or pausing before speech, referred to by people who stutter as "blocks", and the prolongation of certain sounds, usually vowels or semivowels. According to Watkins et al., stuttering is a disorder of "selection, initiation, and execution of motor sequences necessary for fluent speech production." For many people who stutter, repetition is the primary problem. The term "stuttering" covers a wide range of severity, encompassing barely perceptible impediments that are largely cosmetic to severe symptoms that effectively prevent oral communication. In the world, approximately four times as many men as women stutter, encompassing 70 million people worldwide, or about 1% of the world's population.

The impact of stuttering on a person's functioning and emotional state can be severe. This may include fears of having to enunciate specific vowels or consonants, fears of being caught stuttering in social situations, self-imposed isolation, anxiety, stress, shame, being a possible target of bullying (especially in children), having to use word substitution and rearrange words in a sentence to hide stuttering, or a feeling of "loss of control" during speech. Stuttering is sometimes popularly seen as a symptom of anxiety, but there is actually no direct correlation in that direction (though as mentioned the inverse can be true, as social anxiety may actually develop in individuals as a result of their stuttering).

Stuttering is generally not a problem with the physical production of speech sounds or putting thoughts into words. Acute nervousness and stress do not cause stuttering, but they can trigger stuttering in people who have the speech disorder, and living with a stigmatized disability can result in anxiety and high allostatic stress load (chronic nervousness and stress) that reduce the amount of acute stress necessary to trigger stuttering in any given person who stutters, exacerbating the problem in the manner of a positive feedback system; the name 'stuttered speech syndrome' has been proposed for this condition. Neither acute nor chronic stress, however, itself creates any predisposition to stuttering.

The disorder is also "variable", which means that in certain situations, such as talking on the telephone or in a large group, the stuttering might be more severe or less, depending on whether or not the stutterer is self-conscious about their stuttering. Stutterers often find that their stuttering fluctuates and that they have "good" days, "bad" days and "stutter-free" days. The times in which their stuttering fluctuates can be random. Although the exact etiology, or cause, of stuttering is unknown, both genetics and neurophysiology are thought to contribute. There are many treatments and speech therapy techniques available that may help decrease speech disfluency in some people who stutter to the point where an untrained ear cannot identify a problem; however, there is essentially no cure for the disorder at present. The severity of the person's stuttering would correspond to the amount of speech therapy needed to decrease disfluency. For severe stuttering, long-term therapy and hard work is required to decrease disfluency.

Before beginning treatment, an assessment is needed, as diagnosing stuttering requires the skills of a certified speech-language pathologist (SLP).

While there is no complete cure for stuttering, several treatment options exist that help individuals to better control their speech. Many of the available treatments focus on learning strategies to minimize stuttering through speed reduction, breathing regulation, and gradual progression from single-syllable responses to longer words, and eventually more complex sentences. Furthermore, some stuttering therapies help to address the anxiety that is often elicited as a result of stuttering, and consequently exacerbates stuttering symptoms. This method of treatment is referred to as a comprehensive approach, in which the main emphasis of treatment is directed toward improving the speaker's attitudes toward communication and minimizing the negative impact stuttering can have on the speaker's life. Treatment from a qualified S-LP can benefit people who stutter of any age.

Speech language pathologists teach people who stutter to control and monitor the rate at which they speak. In addition, people may learn to start saying words in a slightly slower and less physically tense manner. They may also learn to control or monitor their breathing. When learning to control speech rate, people often begin by practising smooth, fluent speech at rates that are much slower than typical speech, using short phrases and sentences. Over time, people learn to produce smooth speech at faster rates, in longer sentences, and in more challenging situations until speech sounds both fluent and natural. When treating stuttering in children, some researchers recommend that an evaluation be conducted every three months in order to determine whether or not the selected treatment option is working effectively. "Follow-up" or "maintenance" sessions are often necessary after completion of formal intervention to prevent relapse.

According to the fifth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5), Tourette’s may be diagnosed when a person exhibits both multiple motor and one or more vocal tics over the period of a year; the motor and vocal tics need not be concurrent. The onset must have occurred before the age of 18, and cannot be attributed to the effects of another condition or substance (such as cocaine). Hence, other medical conditions that include tics or tic-like movements—such as autism or other causes of tourettism—must be ruled out before conferring a Tourette's diagnosis. Since 2000, the DSM has recognized that clinicians see patients who meet all the other criteria for Tourette's, but do not have distress or impairment.

There are no specific medical or screening tests that can be used in diagnosing Tourette's; it is frequently misdiagnosed or underdiagnosed, partly because of the wide expression of severity, ranging from mild (the majority of cases) or moderate, to severe (the rare, but more widely recognized and publicized cases). Coughing, eye blinking, and tics that mimic unrelated conditions such as asthma are commonly misdiagnosed.

The diagnosis is made based on observation of the individual's symptoms and family history, and after ruling out secondary causes of tic disorders. In patients with a typical onset and a family history of tics or obsessive–compulsive disorder, a basic physical and neurological examination may be sufficient.

There is no requirement that other comorbid conditions (such as ADHD or OCD) be present, but if a physician believes that there may be another condition present that could explain tics, tests may be ordered as necessary to rule out that condition. An example of this is when diagnostic confusion between tics and seizure activity exists, which would call for an EEG, or if there are symptoms that indicate an MRI to rule out brain abnormalities. TSH levels can be measured to rule out hypothyroidism, which can be a cause of tics. Brain imaging studies are not usually warranted. In teenagers and adults presenting with a sudden onset of tics and other behavioral symptoms, a urine drug screen for cocaine and stimulants might be necessary. If a family history of liver disease is present, serum copper and ceruloplasmin levels can rule out Wilson's disease. Most cases are diagnosed by merely observing a history of tics.

Secondary causes of tics (not related to inherited Tourette syndrome) are commonly referred to as tourettism. Dystonias, choreas, other genetic conditions, and secondary causes of tics should be ruled out in the differential diagnosis for Tourette syndrome. Other conditions that may manifest tics or stereotyped movements include developmental disorders, autism spectrum disorders, and stereotypic movement disorder; Sydenham's chorea; idiopathic dystonia; and genetic conditions such as Huntington's disease, neuroacanthocytosis, Hallervorden-Spatz syndrome, Duchenne muscular dystrophy, Wilson's disease, and tuberous sclerosis. Other possibilities include chromosomal disorders such as Down syndrome, Klinefelter syndrome, XYY syndrome and fragile X syndrome. Acquired causes of tics include drug-induced tics, head trauma, encephalitis, stroke, and carbon monoxide poisoning. The symptoms of Lesch-Nyhan syndrome may also be confused with Tourette syndrome. Most of these conditions are rarer than tic disorders, and a thorough history and examination may be enough to rule them out, without medical or screening tests.

Although not all people with Tourette's have comorbid conditions, most Tourette's patients presenting for clinical care at specialty referral centers may exhibit symptoms of other conditions along with their motor and phonic tics. Associated conditions include attention-deficit hyperactivity disorder (ADD or ADHD), obsessive–compulsive disorder (OCD), learning disabilities and sleep disorders. Disruptive behaviors, impaired functioning, or cognitive impairment in patients with comorbid Tourette's and ADHD may be accounted for by the comorbid ADHD, highlighting the importance of identifying and treating comorbid conditions. Disruption from tics is commonly overshadowed by comorbid conditions that present greater interference to the child. Tic disorders in the absence of ADHD do not appear to be associated with disruptive behavior or functional impairment, while impairment in school, family, or peer relations is greater in patients who have more comorbid conditions and often determines whether therapy is needed.

Because comorbid conditions such as OCD and ADHD can be more impairing than tics, these conditions are included in an evaluation of patients presenting with tics. "It is critical to note that the comorbid conditions may determine functional status more strongly than the tic disorder," according to Samuel Zinner, MD. The initial assessment of a patient referred for a tic disorder should include a thorough evaluation, including a family history of tics, ADHD, obsessive–compulsive symptoms, and other chronic medical, psychiatric and neurological conditions. Children and adolescents with TS who have learning difficulties are candidates for psychoeducational testing, particularly if the child also has ADHD. Undiagnosed comorbid conditions may result in functional impairment, and it is necessary to identify and treat these conditions to improve functioning. Complications may include depression, sleep problems, social discomfort, self-injury, anxiety, personality disorders, oppositional defiant disorder, and conduct disorders.

Immediate treatment of drug induced OGC can be achieved with intravenous antimuscarinic benzatropine or procyclidine; which usually are effective within 5 minutes, although may take as long as 30 minutes for full effect. Further doses of procyclidine may be needed after 20 minutes. Any causative new medication should be discontinued. Also can be treated with 25 mg diphenhydramine.

In considering whether an individual has thought disorder, patterns of their speech are closely observed. Although it is normal to exhibit some of the following during times of extreme stress (e.g. a cataclysmic event or the middle of a war) it is the degree, frequency, and the resulting functional impairment that leads to the conclusion that the person being observed has a thought disorder.

- "Alogia" (also "poverty of speech") – A poverty of speech, either in amount or content; it can occur as a negative symptom of schizophrenia.

- "Blocking" – An abrupt stop in the middle of a train of thought; the individual may or may not be able to continue the idea. This is a type of formal thought disorder that can be seen in schizophrenia.

- "Circumstantiality" (also "circumstantial thinking", or "circumstantial speech") – An inability to answer a question without giving excessive, unnecessary detail. This differs from tangential thinking, in that the person does eventually return to the original point.

- "Clanging" or "Clang association" – a severe form of flight of ideas whereby ideas are related only by similar or rhyming sounds rather than actual meaning. This may be heard as excessive rhyming and/or alliteration. e.g. "Many moldy mushrooms merge out of the mildewy mud on Mondays." "I heard the bell. Well, hell, then I fell." It is most commonly seen in bipolar affective disorder (manic phase), although it is often observed in patients with primary psychoses, namely schizophrenia and schizoaffective disorder.

- "Derailment" (also "loose association" and "knight's move thinking") – Thought and/or speech move, either spontaneously or in response to an internal stimulus (distinguishing derailment from "distractible speech," "infra"), from the topic's track onto another which is obliquely related or unrelated. e.g. "The next day when I'd be going out you know, I took control, like uh, I put bleach on my hair in California."

- "Distractible speech" – During mid speech, the subject is changed in response to an external stimulus. e.g. "Then I left San Francisco and moved to... where did you get that tie?"

- "Echolalia" – Echoing of another's speech that may only be committed once, or may be continuous in repetition. This may involve repeating only the last few words or last word of the examiner's sentences. This can be a symptom of Tourette's Syndrome. e.g. "What would you like for dinner?", "That's a good question. "That's a good question". "That's a good question". "That's a good question"."

- "Evasive interaction" – Attempts to express ideas and/or feelings about another individual come out as evasive or in a diluted form, e.g.: "I... er ah... you are uh... I think you have... uh-- acceptable erm... uh... hair."

- "Flight of ideas" – a form of formal thought disorder marked by abrupt leaps from one topic to another, albeit with discernable links between successive ideas, perhaps governed by similarities between subjects or, in somewhat higher grades, by rhyming, puns, and word plays (clang associations), or innocuous environmental stimuli – e.g., the sound of birds chirping. It is most characteristic of the manic phase of bipolar illness.

- "Illogicality" – Conclusions are reached that do not follow logically (non-sequiturs or faulty inferences). e.g. "Do you think this will fit in the box?" draws a reply like "Well duh; it's brown, isn't it?"

- "Incoherence (word salad)" – Speech that is unintelligible because, though the individual words are real words, the manner in which they are strung together results in incoherent gibberish, e.g. the question "Why do people comb their hair?" elicits a response like "Because it makes a twirl in life, my box is broken help me blue elephant. Isn't lettuce brave? I like electrons, hello please!"

- "Loss of goal" – Failure to follow a train of thought to a natural conclusion. e.g. "Why does my computer keep crashing?", "Well, you live in a stucco house, so the pair of scissors needs to be in another drawer."

- "Neologisms" – New word formations. These may also involve elisions of two words that are similar in meaning or in sound. e.g. "I got so angry I picked up a dish and threw it at the geshinker."

- "Perseveration" – Persistent repetition of words or ideas even when another person attempts to change the topic. e.g. "It's great to be here in Nevada, Nevada, Nevada, Nevada, Nevada." This may also involve repeatedly giving the same answer to different questions. e.g. "Is your name Mary?" "Yes." "Are you in the hospital?" "Yes." "Are you a table?" "Yes." Perseveration can include palilalia and logoclonia, and can be an indication of organic brain disease such as Parkinson's.

- "Phonemic paraphasia" – Mispronunciation; syllables out of sequence. e.g. "I slipped on the lice and broke my arm."

- "Pressure of speech" – Unrelenting, rapid speech without pauses. It may be difficult to interrupt the speaker, and the speaker may continue speaking even when a direct question is asked.

- "Self-reference" – Patient repeatedly and inappropriately refers back to self. e.g. "What's the time?", "It's 7 o'clock. That's my problem."

- "Semantic paraphasia" – Substitution of inappropriate word. e.g. "I slipped on the coat, on the ice I mean, and broke my book."

- "Stilted speech" – Speech characterized by the use of words or phrases that are flowery, excessive, and pompous. e.g. "The attorney comported himself indecorously."

- "Tangentiality" – Wandering from the topic and never returning to it or providing the information requested. e.g. in answer to the question "Where are you from?", a response "My dog is from England. They have good fish and chips there. Fish breathe through gills."

- "Word approximations" – Old words used in a new and unconventional way. e.g. "His boss was a ."

The concept of thought disorder has been criticized as being based on circular or incoherent definitions. For example, thought disorder is inferred from disordered speech, based on the assumption that disordered speech arises because of disordered thought. Incoherence, or word salad, refers to speech that is unconnected and conveys no meaning to the listener.

Furthermore, although thought disorder is typically associated with psychosis, similar phenomena can appear in different disorders, potentially leading to misdiagnosis—for example, in the case of incomplete yet potentially fruitful thought processes.

It has been suggested that individuals with autism spectrum disorders (ASD) display language disturbances like those found in schizophrenia; a 2008 study found that children and adolescents with ASD showed significantly more illogical thinking and loose associations than control subjects. The illogical thinking was related to cognitive functioning and executive control; the loose associations were related to communication symptoms and to parent reports of stress and anxiety.

Drugs that can trigger an oculogyric crisis include neuroleptics (such as haloperidol, chlorpromazine, fluphenazine, olanzapine), carbamazepine, chloroquine, cisplatin, diazoxide, levodopa, lithium, metoclopramide, lurasidone, domperidone, nifedipine, pemoline, phencyclidine ("PCP"), reserpine, and cetirizine, an antihistamine. High-potency neuroleptics are probably the most common cause in the clinical setting.

Other causes can include postencephalitic Parkinson's, Tourette's syndrome, multiple sclerosis, neurosyphilis, head trauma, bilateral thalamic infarction, lesions of the fourth ventricle, cystic glioma of the third ventricle, herpes encephalitis, kernicterus and juvenile Parkinson's.