Assessing Formal Thought Disorder in Forensic Psychological Evaluations

Formal thought disorder refers to disturbances in the organization and expression of thought. It is often associated with psychotic disorders, including schizophrenia spectrum disorders, though disorganized communication can also occur for a variety of other reasons. In clinical and forensic psychological evaluations, the presence or absence of formal thought disorder may be relevant to diagnosis, treatment planning, competency to stand trial, criminal responsibility, violence risk, and other questions involving a person’s mental condition or functional capacities. However, as with many psychological constructs, the importance of formal thought disorder does not mean it can be assessed casually or inferred from only a vague impression that the person was “odd,” “confused,” or “difficult to follow.”

In a recent article published in BJPsych Advances, Palaniyappan, Delgaram-Nejad, and Chen discuss how clinicians can more effectively elicit formal thought disorder during clinical interviews. The article focuses less on simply defining types of thought disorder and more on the practical question of how the evaluator should structure the interview in order to observe the person’s thinking. This distinction is important. A person’s thought process is usually assessed through speech. As a result, the evaluator is not directly observing “thought” itself, but rather the person’s ability to organize, express, clarify, and sustain communication in response to different types of questions and interpersonal demands.

Formal thought disorder is different from delusions or hallucinations. Delusions relate to the content of thought. Hallucinations relate to perceptual experiences. Formal thought disorder relates to the organization and communication of thought. A defendant may report bizarre beliefs while still speaking in a coherent and goal-directed manner. Another defendant may deny hallucinations or delusions but become increasingly disorganized when asked to provide a narrative, explain the sequence of events, answer abstract questions, or clarify the meaning of prior statements. Therefore, the evaluator should be cautious not to equate psychosis with thought disorder, and should also avoid assuming the absence of thought disorder simply because the person does not openly endorse psychotic symptoms.

The article by Palaniyappan and colleagues emphasizes that formal thought disorder is not always apparent during routine conversation. Some examinees provide brief answers. Others may appear organized when discussing familiar or concrete topics, but have more difficulty when asked to explain abstract concepts, describe emotionally significant events, organize a sequence of events, or respond to clarification questions. This is clinically significant because a short or overly structured interview may fail to reveal disorganized thinking that becomes apparent only under greater cognitive or interpersonal demand. In this way, the adequacy of the assessment depends not only on what the person says, but also on what the evaluator asks the person to do.

The nature of an evaluation designed to assess for formal thought disorder will usually involve several types of interview tasks. First, the evaluator will generally ask open-ended questions that allow the person to speak in a relatively spontaneous manner. This may include questions about the person’s background, daily activities, recent events, symptoms, relationships, legal circumstances, or other relevant topics. The purpose is not merely to gather historical information, but also to observe whether the person can remain on topic, provide a coherent account, maintain logical connections between ideas, and communicate in a manner that can be reasonably followed by the listener.

Second, the evaluator may ask questions that require the person to organize information in a more complex manner. For example, the person may be asked to describe the sequence of events leading to an arrest, explain their understanding of a legal situation, interpret another person’s behavior, describe how they made a decision, or provide reasons for a particular belief. These types of questions may be especially relevant in forensic evaluations because legal capacities often depend on reasoning, appreciation, communication, and the ability to apply information to one’s own circumstances. A defendant who can repeat simple facts may still struggle to provide rationally organized explanations when asked to discuss more complex or personally relevant matters.

Third, the evaluator may use clarification questions. This is particularly important. If a person makes a statement that appears tangential, illogical, or difficult to understand, the evaluator should not immediately assume it reflects psychosis or formal thought disorder. The better practice is often to ask the person what they mean, how the statement relates to the question, or whether they can explain it in a different way. In some cases, the person is able to clarify the statement and restore coherence. In other cases, attempts at clarification lead to further disorganization. The response to clarification may be more informative than the original unclear statement.

This has obvious relevance for forensic psychological evaluations. In competency to stand trial evaluations, the issue is not simply whether the defendant has a mental disorder. The relevant question is whether the defendant has sufficient present ability to understand the proceedings and assist counsel, as those capacities are defined by the applicable jurisdiction. Formal thought disorder may interfere with those capacities when it impairs the defendant’s ability to communicate with counsel, provide a coherent account of events, understand legal options, weigh decisions, or maintain rational participation in the defense. However, the presence of disorganized speech does not automatically establish incompetence. The evaluator must still explain how the observed disorganization affects the specific legally relevant abilities.

Formal thought disorder may also be relevant in criminal responsibility evaluations. In such evaluations, the focus is generally on the defendant’s mental state and capacities at the time of the alleged offense. Current evidence of formal thought disorder may be important, but it does not answer the legal question by itself. The evaluator must consider the person’s presentation around the time of the alleged offense, including police reports, witness statements, body camera footage, interrogation video, jail or hospital records, collateral interviews, and other available information. A person may appear disorganized at the time of the evaluation but may have been organized at the time of the offense. The reverse may also occur. Therefore, current interview observations should be integrated with collateral information rather than treated as a substitute for it.

The assessment of formal thought disorder may also be relevant when there are concerns about exaggeration, feigning, or malingering. Some individuals may attempt to appear psychotic by giving bizarre, overly dramatic, or intentionally incoherent answers. At the same time, genuine psychotic disorders can involve unusual, inconsistent, or difficult-to-follow communication. For this reason, the evaluator should avoid relying on a single unusual response as proof of either genuine psychosis or feigning. Instead, the evaluator should consider the consistency of the presentation across the interview, psychological testing, treatment records, collateral sources, observed behavior, and the person’s known history. When available and appropriate, symptom validity or response validity measures may provide additional information, but they do not eliminate the need for careful clinical observation.

There are also several limitations that must be considered. Disorganized communication is not specific to schizophrenia or psychotic disorders. It may be affected by intellectual disability, neurocognitive disorder, traumatic brain injury, mania, severe depression, anxiety, intoxication, withdrawal, language limitations, cultural factors, educational background, or the stress of the evaluation itself. A person who speaks English as a second language may appear less coherent than they would in their primary language. A person with limited education may struggle with abstract questions. A highly anxious defendant may lose track of a question or provide incomplete answers. These possibilities do not mean the evaluator should ignore disorganized speech, but they do mean the evaluator should consider alternative explanations before reaching a conclusion.

In forensic reports, it is often not enough to state that the person’s thought process was “linear,” “tangential,” “circumstantial,” or “disorganized.” Those terms may be accurate, but they are conclusions. A more useful report explains the basis for those conclusions. What questions were asked? Did the person become disorganized only when discussing emotionally charged topics? Was the person able to clarify unclear statements when asked? Did disorganization occur across multiple topics or only in one narrow area? Were there verbatim examples? Were alternative explanations considered?

In conclusion, formal thought disorder is an important clinical observation, but it should be assessed through a careful and deliberate interview process. The evaluator should create opportunities for the person to speak spontaneously, organize complex information, respond to clarification, and demonstrate whether their communication remains coherent under increased demand. In forensic contexts, the evaluator must then connect those observations to the specific legal question being addressed. The ultimate issue is not simply whether the person sounded disorganized during an interview. The more important question is what the disorganization shows, how reliably it was elicited, what else may explain it, and whether it affects the legally relevant capacities at issue.

Reference:

Palaniyappan, L., Delgaram-Nejad, O., & Chen, E. Y. H. (2026). How to elicit thought disorder during clinical interviews: A practical guide. BJPsych Advances. Advance online publication. https://doi.org/10.1192/bja.2026.10213