but is also associated with other conditions (including mood disorders, dementia, mania, and neurological diseases). impaired attention, poor memory, and difficulty formulating abstract concepts may also reflect td, and can be observed and assessed with mental-status tests such as serial sevens or memory tests. types thirty symptoms (or features) of td have been described, including: alogia: a poverty of speech in amount or content, it is classified as a negative symptom of schizophrenia. when further classifying symptoms, poverty of speech content (little meaningful content with a normal amount of speech) is a disorganization symptom. under sans, thought blocking is considered a part of alogia, and so is increased latency in response. thought blocking (also known as deprivation of thought and obstructive thought): an abrupt stop in the middle of a train of thought which may not be able to be continued. circumstantial speech (also known as circumstantial thinking): an inability to answer a question without excessive, unnecessary detail. this differs from tangential thinking in that the person does eventually return to the original point. a patient may answer the question "how have you been sleeping lately?" with "oh, i go to bed early, so i can get plenty of rest. i like to listen to music or read before bed. right now i'm reading a good mystery. maybe i'll write a mystery someday. but it isn't helping, reading i mean. i have been getting only 2 or 3 hours of sleep at night." clanging: an instance where ideas are related only by similar or rhyming sounds rather than actual meaning. this may be heard as excessive rhyming or alliteration ("many moldy mushrooms merge out of the mildewy mud on mondays", or "i heard the bell. well, hell, then i fell"). it is most commonly seen in the manic phase of bipolar disorder, although it is also often observed in patients with schizophrenia and schizoaffective disorder. derailment (also known as loose association and knight's move thinking): thought frequently moves from one idea to another which is obliquely related or unrelated, often appearing in speech but also in writing ("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: in mid-speech, the subject is changed in response to a nearby stimulus ("then i left san francisco and moved to ... where did you get that tie?") echolalia: echoing of another's speech, once or in repetition. it may involve repeating only the last few words (or the last word) of another person's sentences, and is common on the autism spectrum and in tourette syndrome. evasion: the next logical idea in a sequence is replaced with another idea closely (but not accurately or appropriately) related to it; also known as paralogia and perverted logic. flight of ideas: a form of ftd marked by abrupt leaps from one topic to another, possibly with discernible links between successive ideas, perhaps governed by similarities between subjects or by rhyming, puns, wordplay, or innocuous environmental stimuli (such as the sound of birds chirping). it is most characteristic of the manic phase of bipolar disorder. illogicality: conclusions are reached which do not follow logically (non sequiturs or faulty inferences). "do you think this will fit in the box?" is answered with, "well of course; it's brown, isn't it?" incoherence (word salad): speech which is unintelligible because the individual words are real, but the manner in which they are strung together results in gibberish. 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!" neologisms: completely new words (or phrases) whose origins and meanings are usually unrecognizable ("i got so angry i picked up a dish and threw it at the geshinker"). they may also involve elisions of two words which are similar in meaning or sound. although neologisms may refer to words formed incorrectly whose origins are understandable (such as "headshoe" for "hat"), these can be more clearly referred to as word approximations. overinclusion: the failure to eliminate ineffective, inappropriate, irrelevant, extraneous details associated with a particular stimulus. perseveration: persistent repetition of words or ideas, even when another person tries to change the subject. ("it's great to be here in nevada, nevada, nevada, nevada, nevada.") it may also involve repeatedly giving the same answer to different questions ("is your name mary?" "yes." "are you in the hospital?" "yes." "are you a table?" "yes"). perseveration can include palilalia and logoclonia, and may indicate an organic brain disease such as parkinson's disease. phonemic paraphasia: mispronunciation; syllables out of sequence ("i slipped on the lice and broke my arm"). pressured speech: rapid speech without pauses, which is difficult to interrupt. referential thinking: viewing innocuous stimuli as having a specific meaning for the self ("what's the time?" "it's 7 o'clock. that's my problem"). semantic paraphasia: substitution of inappropriate words ("i slipped on the coat, on the ice i mean, and broke my book"). stilted speech: speech characterized by words or phrases which are flowery, excessive, and pompous ("the attorney comported himself indecorously"). tangential speech: wandering from the topic and never returning to it, or providing requested information ("where are you from?" "my dog is from england. they have good fish and chips there. fish breathe through gills"). verbigeration: meaningless, stereotyped repetition of words or phrases which replace understandable speech; seen in schizophrenia. terminology psychiatric and psychological glossaries in 2015 and 2017 defined thought disorder' as disturbed thinking or cognition which affects communication, language, or thought content including poverty of ideas, neologisms, paralogia, word salad, and delusions (disturbances of thought content and form), and suggested the more-specific terms content thought disorder (ctd) and formal thought disorder (ftd). ctd was defined as a td characterized by multiple fragmented delusions, and ftd was defined as a disturbance in the form or structure of thinking. the 2013 dsm-5 only used the term ftd, primarily as a synonym for disorganized thinking and speech. this contrasts with the 1992 icd-10 (which only used the word "thought disorder", always accompanied with "delusion" and "hallucination") and a 2002 medical dictionary which generally defined thought disorders similarly to the psychiatric glossaries and used the word in other entries as the icd-10 did. a 2017 psychiatric text describing thought disorder as a "disorganization syndrome" in the context of schizophrenia: "thought disorder" here refers to disorganization of the form of thought and not content. an older use of the term "thought disorder" included the phenomena of delusions and sometimes hallucinations, but this is confusing and ignores the clear differences in the relationships between symptoms that have become apparent over the past 30 years. delusions and hallucinations should be identified as psychotic symptoms, and thought disorder should be taken to mean formal thought disorders or a disorder of verbal cognition. — phenomenology of schizophrenia (2017), the symptoms of schizophrenia the text said that some clinicians use the term "formal thought disorder" broadly, referring to abnormalities in thought form with psychotic cognitive signs or symptoms, and studies of cognition and subsyndromes in schizophrenia may refer to ftd as conceptual disorganization or disorganization factor. some disagree: unfortunately, "thought disorder" is often involved rather loosely to refer to both ftd and delusional content. for the sake of clarity, the unqualified use of the phrase "thought disorder" should be discarded from psychiatric communication. even the designation "formal thought disorder" covers too wide a territory. it should always be made clear whether one is referring to derailment or loose associations, flight of ideas, or circumstantiality.— the mental status examination, the medical basis of psychiatry (2016) course, diagnosis, and prognosis it was believed that td occurred only in schizophrenia, but later findings indicate that it may occur in other psychiatric conditions (including mania) and in people without mental illness. not all people with schizophrenia have a td; the condition is not specific to the disease. depiction of an individual with bipolar disorder, illustrating the conflicting thoughts going through their mind in manic and depressive states when defining thought-disorder subtypes and classifying them as positive or negative symptoms, nancy andreasen found that different subtypes of td occur at different frequencies in those with mania, depression, and schizophrenia. people with mania have pressured speech as the most prominent symptom, and have rates of derailment, tangentiality, and incoherence as prominent as in those with schizophrenia. they are likelier to have pressured speech, distractibility, and circumstantiality. people with schizophrenia have more negative td, including poverty of speech and poverty of content of speech, but also have relatively high rates of some positive td. derailment, loss of goal, poverty of content of speech, tangentiality and illogicality are particularly characteristic of schizophrenia. people with depression have relatively-fewer tds; the most prominent are poverty of speech, poverty of content of speech, and circumstantiality. andreasen noted the diagnostic usefulness of dividing the symptoms into subtypes; negative tds without full affective symptoms suggest schizophrenia. she also cited the prognostic value of negative-positive-symptom divisions. in manic patients, most tds resolve six months after evaluation; this suggests that tds in mania, although as severe as in schizophrenia, tend to improve. in people with schizophrenia, however, negative tds remain after six months and sometimes worsen; positive tds somewhat improve. a negative td is a good predictor of some outcomes; patients with prominent negative tds are worse in social functioning six months later. more prominent negative symptoms generally suggest a worse outcome; however, some people may do well, respond to medication, and have normal brain function. positive symptoms vary similarly. a prominent td at illness onset suggests a worse prognosis, including: illness begins earlier increased risk of hospitalization decreased functional outcomes increased disability rates increased inappropriate social behaviors td which is unresponsive to treatment predicts a worse illness course. in schizophrenia, td severity tends to be more stable than hallucinations and delusions. prominent tds are more unlikely to diminish in middle age, compared with positive symptoms. less-severe td may occur during the prodromal and residual periods of schizophrenia. treatment for thought disorder may include psychotherapy, such as cognitive behavior therapy (cbt), and psychotropic medications. the dsm-5 includes delusions, hallucinations, disorganized thought process (formal thought disorder), and disorganized or abnormal motor behavior (including catatonia) as key symptoms of psychosis. schizophrenia-spectrum disorders such as schizoaffective disorder and schizophreniform disorder typically consist of prominent hallucinations, delusions and ftd; the latter presents as severely disorganized, bizarre, and catatonic behavior. psychotic disorders due to medical conditions and substance use typically consist of delusions and hallucinations. the rarer delusional disorder and shared psychotic disorder typically present with persistent delusions. ftds are commonly found in schizophrenia and mood disorders, with poverty of speech content more common in schizophrenia. psychoses such as schizophrenia and bipolar mania are distinguishable from malingering, when an individual fakes illness for other gains, by clinical presentations; malingerers feign thought content with no irregularities in form such as derailment or looseness of association. negative symptoms, including alogia, may be absent, and chronic thought disorder is typically distressing. autism spectrum disorders (asd) whose diagnosis requires the onset of symptoms before three years of age can be distinguished from early-onset schizophrenia; schizophrenia under age 10 is extremely rare, and asd patients do not display ftds. however, it has been suggested that individuals with 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 parent reports of stress and anxiety. rorschach tests have been useful for assessing td in disturbed patients. a series of inkblots are shown, and patient responses are analyzed to determine disturbances of thought. the nature of the assessment offers insight into the cognitive processes of another, and how they respond to equivocal stimuli. hermann rorschach developed this test to diagnose schizophrenia after realizing that people with schizophrenia gave drastically different interpretations of klecksographie inkblots from others whose thought processes were considered normal, and it has become one of the most widely-used assessment tools for diagnosing tds. the thought disorder index (tdi), also known as the delta index, was developed to help further determine the severity