The Diagnostic Process

Learning Objectives

  • Explain the steps and people involved in the diagnostic process, including the case formulation

The word diagnosis commonly refers to the identification of the nature and cause of an illness. When a mental health professional diagnoses a client or patient, the first steps can be summarized as gathering information, narrowing down the options, and formulating a diagnostic impression. 

The diagnostic process involves gathering relevant information from a person through a detailed interview that includes finding out the person’s main concerns, their symptoms, and their life history. This information includes the results from psychological tests or questionnaires and may include information obtained from the person’s family and/or from previous treatment records. Mental health professionals use this first phase of working with clients before proceeding with the treatment itself. More specifically, before a diagnosis is given, they determine whether the person’s symptoms match the DSM’s criteria for a particular mental disorder, and if there is a significant level of disturbance in the person’s cognitive, emotional, or behavioral functioning.  

Clients, Consumers, and Patients

Why all the different terms? Patient and client are terms that carry different connotations, often depending on the method of treatment, or treatment site. For many professionals, a patient is any recipient of health care services performed by healthcare professionals, and client reflects that people in treatment collaborate with those who treat them, notably, the clinician—a professional who works directly with patients or clients and may diagnose, treat, and otherwise care for them. A term adopted by many users of psychiatric services is consumer.” This term was chosen to eliminate the “patient” label and restore the person to an active role as a user or consumer of services.[1] The terms clients and consumers imply a much more active role on the part of the individual and therefore imply that healthcare professionals are not the only ones who have expertise in healthy functioning.

Diagnostic Procedures

The main goal of the information-gathering model is to accurately diagnose, plan treatments, and evaluate treatment effectiveness. The key to diagnosis is gaining as clear a description as possible of a client’s or patient’s symptoms. Mental health professionals listen to what the client or patient reports, and they observe quite a number of things, such as behavior and emotional expression. Routine diagnostic practice in mental health services typically involves an interview known as a mental status examination, where evaluations are made of appearance and behavior, self-reported symptoms, mental health history, and current life circumstances.

We will discuss a variety of assessment tools used by mental health professionals to determine the extent to which these symptoms correspond with the diagnostic criteria of a given disorder. This approach to diagnosis is more systematic, and allows one to determine the exact nature of a client’s symptoms, the length of time the client has experienced these symptoms, and any associated symptoms.

Elements of a Diagnosis

By listening to clients as they describe the experience of their symptoms, and following up with assessment tools (not always, but often), the mental health professional begins to formulate the principal diagnosis—or the reason for the visit. This means determining the single diagnosis that is most relevant to the person’s chief complaint or need for treatment; this diagnosis will be the main focus of clinical attention or treatment.

After determining the primary reason the individual is seeking professional help, a differential diagnosis is commonly used. Two different diagnoses can be attached to a patient who is exhibiting symptoms that could fit into either diagnosis. For example, a patient who has been diagnosed with bipolar disorder may also be given a differential diagnosis of borderline personality disorder, given the similarity in the symptoms of both conditions. Where multiple alternatives are possible, this method is akin to the process of elimination or ruling out of alternative diagnoses, a crucial step in the diagnostic process.

Many patients have additional diagnoses. Comorbidity refers to the presence of more than one diagnosis occurring in an individual at the same time. In the context of mental health, comorbidity often refers to disorders that are often coexistent with each other, such as substance use disorder and depression (the most common comorbidities involve the concurrence of substance use disorders with other mental disorders). Multiple diagnoses are usually presented in a hierarchy descending from the condition of most significance to that of the least concern.

The Case Formulation

Once the mental health professional makes a formal diagnosis, they then analyze the factors that may have influenced the patient or client’s current psychological state. A clinical formulation, also known as case formulation or case conceptualization, is that analysis, or a theoretically based explanation of the information obtained from a clinical assessment. It offers a hypothesis about the cause and nature of the presenting problems (e.g., background history, presenting concerns, and manifestation and progression of behavioral signs and symptoms over time), and is considered an adjunct or alternative approach to the more categorical approach of psychiatric diagnosis. These formulations are used to communicate a hypothesis and provide a framework for developing the most suitable treatment approach, rather than labels or diagnostic codes. It gives a rich description of the client’s personal history and pieces together how the disorder evolved. It is most commonly used by clinical psychologists and psychiatrists and is deemed to be a core component of these professions. Mental health nurses and social workers may also use formulations. As mental health professionals, we need to consider both the purpose of our communication and the audience for that communication. As professionals, we must also consider the potential misuse of documents by others, which will influence the way that we present our case formulation.

Types of Formulation

Different psychological schools or models utilize clinical formulations, including cognitive-behavioral therapy (CBT) and related therapies: systemic therapy, psychodynamic therapy, and applied behavior analysis. The structure and content of a clinical formulation is determined by the psychological model (which we will examine more closely in another module). Most systems of formulation contain the following broad categories of information:

  • symptoms and problems
  • precipitating stressors or events
  • predisposing life events or stressors
  • an explanatory mechanism that links the preceding categories together
  • a description of the precipitants and maintaining influences of the person’s problems

Many psychologists use an integrative psychotherapy approach to formulationor the integration of elements from different schools of psychotherapy in the treatment of a client. This is to take advantage of the benefits of resources from each model the psychologist is trained in, according to the patient’s needs. The case formulation may pull from several psychological models and formations, such as those mentioned below:

  • A cognitive-behavioral model of formulation described by Jacqueline Persons has seven components: problem list, core beliefs, precipitants and activating situations, origins, working hypothesis, treatment plan, and predicted obstacles to treatment.
  • A psychodynamic formulation would consist of a summarizing statement, description of nondynamic factors, description of core psychodynamics using a specific model (such as ego psychology, object relations, or self psychology), and prognostic assessment that identifies the potential areas of resistance in therapy.
  • Behavioral case formulations used in applied behavior analysis and behavior therapy are built on a rank list of problem behaviors. Such functional analysis is also used in acceptance and commitment therapy. Functional analysis looks at setting events (ecological variables, history effects, and motivating operations); antecedents; behavior chainsthe problem behavior; and the consequences, short- and long-term, for the behavior

Watch It

Watch this video to see all the components that go into a case formulation for a client. The video specifically mentions one type of therapy, acceptance and commitment therapy (ACT), but the concepts apply generally to all types of psychotherapy.

You can view the transcript for “ACT Case Conceptualization: Assessing the 6 Core Processes” here (opens in new window).

Cultural Formulation

A cultural formulation is the systematic review of a person’s cultural background and the role of culture in the manifestation of symptoms and dysfunction. It is argued that a cultural perspective can help psychiatrists become aware of the hidden assumptions and limitations of current psychiatric theory and practice and can identify new approaches appropriate for treating the increasingly diverse populations seen in psychiatric services around the world. The DSM-5 includes a Cultural Formulation Interview that aims to help clinicians contextualize diagnostic assessment. A related approach to cultural assessment involves cultural consultation that works with interpreters and cultural brokers to develop a cultural formulation and treatment plan that can assist clinicians.

Cross-cultural psychiatry (also known as ethnopsychiatry, transcultural psychiatry, or cultural psychiatry) is a branch of psychiatry concerned with the cultural context of mental disorders and the challenges of addressing ethnic diversity in psychiatric services. It looks at whether psychiatric classifications of disorders are appropriate to different cultures or ethnic groups. It often argues that psychiatric illnesses represent social constructs as well as genuine medical conditions, and as such have social uses peculiar to the social groups in which they are created and legitimized. It studies psychiatric classifications in different cultures, whether informal (e.g., category terms used in different languages) or formal (for example the World Health Organization’s ICD, the American Psychiatric Association’s DSM, or the Chinese Society of Psychiatry’s CCMD). The field has increasingly had to address the process of globalization. It is said every city has a different culture and that the urban environment, and how people adapt or struggle to adapt to it, can play a crucial role in the onset or worsening of mental illness.

Reflecting advances in medical anthropology, the DSM-5 replaced the term culture-bound syndrome (or folk illness—a combination of psychiatric and somatic symptoms that are considered to be a recognizable disease only within a specific society or culture) with a set of terms covering cultural concepts of distress: cultural syndromes (which may not be bound to a specific culture but circulate across cultures), cultural idioms of distress (local modes of expressing suffering that may not be syndromes), causal explanations (that attribute symptoms or suffering to specific causal factors rooted in local ontologies), and folk diagnostic categories (which may be part of ethnomedical systems and healing practices).

dig deeper: Dhat Syndrome

One argument to support the concept of culture-bound syndromes comes from research on dhat syndrome, as it has been specified as a culture-bound syndrome specific to the culture of the Indian subcontinent. The DSM-4 listed it as a folk diagnostic term used in India to refer to severe anxiety and hypochondriacal concerns associated with the discharge of semen, whitish discoloration of the urine, and feelings of weakness and exhaustion. Similar to jiryan (India), sukra prameha (Sri Lanka), and shen-k’uei (China), dhat syndrome in the DSM-5 is listed as a term that was coined in South Asia little more than half a century ago to account for common clinical presentations of young male patients who attributed their various symptoms to semen loss. Despite the name, it is not a discrete syndrome but rather a cultural explanation of distress for patients who refer to diverse symptoms, such as anxiety, fatigue, weakness, weight loss, impotence, other multiple somatic complaints, and depressive mood. The cardinal feature is anxiety and distress about the loss of dhat in the absence of any identifiable physiological dysfunction.

Research in health care settings has yielded diverse estimates of the syndrome’s prevalence (e.g., 64% of men attending psychiatric clinics in India for sexual complaints; 30% of men attending general clinics in Pakistan). Related conditions in DSM-5 are major depressive disorder, persistent depressive disorder, generalized anxiety disorder, somatic symptom disorder, illness anxiety disorder, erectile disorder, early (premature) ejaculation, and other specified or unspecified sexual dysfunction. [2] 

Think it over

Cultural influence has been shown to influence the appearance of psychiatric disorders. In the context of psychiatric disorders, cultural influence is present at multiple levels. First, culture and society shape the meanings and expressions people give to various emotions. Second, cultural factors determine which symptoms or signs are normal and abnormal. Third, culture helps define what compromises health and illness. Lastly, it shapes the illness behavior and help-seeking behavior. Overall, cultural influence on psychiatric disorders include conditions other than culture-bound disorders. The ongoing question about culture-bound syndrome continues as researchers ask themselves, “Does culture impact only the culture-bound syndrome?”

Planning the Treatment

Following an initial assessment, the client or patient and therapist come to an agreement called the treatment plan. This is a type of contract that specifies the goals of treatment; treatment procedures; and a regular schedule for the time, place, and duration of their treatment sessions. Sometimes this treatment contract is written down explicitly, but more often it is discussed between the individual seeking therapy and therapist.[3] Services are based in psychiatric hospitals or in the community. Determining the treatment site (most often private therapist’s outpatient clinic or office) is an important part of planning treatment. Community mental health centers (CMHCs) provide for community-based care as an alternative to institutionalization. At these centers, patients can be treated while working and living at home.

The importance of the therapeutic relationship, also known as therapeutic alliance, between client and therapist is often regarded as crucial to psychotherapy. Psychotherapy focuses on the use of psychological methods, particularly when based on regular personal interaction with adults, to help a person change behavior and overcome problems in desired ways. Psychotherapists may be mental health professionals such as psychiatrists, psychologists, mental health nurses, clinical social workers, marriage and family therapists, or professional counselors. Psychotherapy aims to improve an individual’s well-being and mental health; to resolve or mitigate troublesome behaviors, beliefs, compulsions, thoughts, or emotions; and to improve relationships and social skills. There is also a range of psychotherapies designed for children and adolescents, which typically involve play. Certain psychotherapies are considered evidence-based for treating diagnosed mental disorders. Others have been criticized as pseudoscience. There are over a thousand different psychotherapy techniques, some being minor variations, while others are based on very different conceptions of psychology, ethics (how to behave professionally), or techniques. Most involve one-to-one sessions between the client and therapist, but some are conducted with groups, including families.

In practice, clinical and counseling psychologists work with individuals, couples, families, or groups in a variety of settings, including private practices, hospitals, mental health organizations, schools, businesses, and non-profit agencies. Other than providing psychological treatment (psychotherapy), clinical and counseling psychologists can offer a range of professional services, including administering and interpreting psychological assessment and testing, and providing expert testimony (forensics). 

Although clinical and counseling psychologists and psychiatrists share the same fundamental aim—the alleviation of mental distress—their training, outlook, and methodologies are often different. Perhaps the most significant difference is that psychiatrists are licensed physicians, and, as such, psychiatrists are apt to use the medical model to assess mental health problems and to also employ psychotropic medications as a method of addressing mental health problems. Psychologists generally do not prescribe medication, although in some jurisdictions they do have prescription privileges. In five U.S. states (New Mexico, Louisiana, Illinois, Iowa, and Idaho), psychologists with post-doctoral clinical psychopharmacology training have been granted prescriptive authority for mental health disorders. Clinical and counseling psychologists receive extensive training in psychological test administration, scoring, interpretation, and reporting, while psychiatrists are not trained in psychological testing.

Goals of Treatment

Therapy includes immediate, short-term, and long-term goal setting. Goals are an essential part of the treatment plan as they help a client work towards cognitive and behavioral changes. For example, a therapist may use the SMART goals approach by setting goals that are specific, measurable, achievable, realistic, and time-limited.

  • Specific—The goal is to be as clear as possible, such as setting a goal to reduce social anxiety levels so that a client can eat lunch with coworkers by the end of the month.
  • Measurable—The goal should be something you can measure, such as tallying up the number of social interactions a client has, or reducing feelings of anxiety from a 9/10 level to a 4/10 level.
  • Achievable—The goals should be feasible and within reach. If a person has severe social anxiety, having them host a party or go out every night for a week would be difficult short-term goals that are likely unachievable.
  • Realistic and Resourced—Is the goal realistic and possible given the time and resources available to you?
  • Time-limited—The goal should have a specific time frame when it will be reached.[4]

Link to Learning

This APA article, “Understanding Psychotherapy and How It Works” provides a good introductory overview of what you can expect during psychotherapy.

Evidence-Based Practice and Ethical Duties

Professional competence—the ability to accurately assess problems, diagnose psychological disorders, recommend an appropriate course of treatment, and successfully carry out that treatment—varies depending on the degree to which the clinician keeps up to date with the latest research and effectively evaluates the evidence. The APA requires that clinicians be trained in evidence-based practice (EBP) to be equipped to appraise the range of evidence regarding the efficacy of different forms of psychotherapy, to recognize the strengths and limitations of clinical intuition, and to understand the importance of patient preferences and values as well as the relevance of the socio-cultural context in treating clients.

Why does evidence-based practice (EBP) matter for the ethical practice of psychological treatments? Evidence carries ethical imperatives. Both the decision about what is considered to be beneficial in psychotherapy, and the current paucity of research regarding the potential negative effects of psychological treatments, carry ethical implications. It is argued that the failure to pay attention to psychotherapy research effectively risks undermining key requisites included in professional codes of practice for clinical psychology, psychiatry, social work, and allied fields. First, evidence-based practice (EBP) bears repercussions for the clinician’s duty of professional competence, or the responsibility to acquire and apply accurate knowledge. Second, EBP is relevant to the duty to respect patient autonomy—namely, the patient’s right to make informed decisions concerning their treatment plans.

Try It


client: reflects that people in treatment collaborate with those who treat them

clinician: health care professional who works directly with patients and may diagnose, treat, and otherwise care for patients.

clinical and counseling psychologists: mental health professional with training in behavioral science who provide direct service to clients

clinical formulation/case formulation: analyzes the factors that may have influenced the client’s current psychological state

confidentiality: therapist cannot disclose confidential communications to any third party, unless mandated or permitted by law

couples therapy: when two people in an intimate relationship, such as husband and wife, attend counseling together to resolve conflict

cross-cultural psychiatry: a branch of psychiatry concerned with the cultural context of mental disorders and the challenges of addressing ethnic diversity in psychiatric services

culture-bound syndrome: a combination of psychiatric and somatic symptoms that are considered to be a recognizable disease only within a specific society or culture

cultural formulation: a systematic review of a person’s cultural background and the role of culture in the manifestation of symptoms and dysfunction

cultural formulation interview: aims to help clinicians contextualize diagnostic assessment

diagnosis: refers to the identification of the nature and cause of an illness or the identification of the nature and cause of something

family therapy: special form of group therapy consisting of one or more families

group therapy: treatment modality in which five to 10 people with the same issue or concern meet together with a trained clinician

individual therapy: treatment modality in which the client and clinician meet one-on-one

intake: therapist’s first meeting with the client in which the therapist gathers specific information to address the client’s immediate needs

integrative psychotherapy approach to formulation: the integration of elements from different schools of psychotherapy in the treatment of a client

mental status examination (MSE): 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

patient: any recipient of health care services performed by healthcare professionals

psychiatrists: licensed physicians (MD) with specialized training in diagnosing and treating people with psychological disorders

psychologist: health care professional offering psychological services

strategic family therapy: when a therapist guides the therapy sessions and develops treatment plans for each family member for specific problems that can be addressed in a short amount of time

structural family therapy: therapist examines and discusses with the family the boundaries and structure of the family: who makes the rules, who sleeps in the bed with whom, how decisions are made, and what are the boundaries within the family

therapeutic relationship: the relationship between a health care professional and a client (or patient)

treatment plan: collaborative goal setting or outline of how therapy takes place

  1. Halpern, L, Trachtman, H. and Duckworth, K. "From Within: A Consumer Perspective on Psychiatric Hospitals," in Textbook of Hospital Psychiatry, S. Sharfstein, F. Dickerson and J. Oldham eds. American Psychiatric Publishing, 2009, pp. 237–244.
  2. Deb, K. S., & Balhara, Y. P. (2013). Dhat syndrome: a review of the world literature. Indian journal of psychological medicine, 35(4), 326–331.
  3. “What Is Psychotherapy?” American Psychological Association.
  4. wikiHow. “How to Write a Mental Health Treatment Plan.” Accessed December 9, 2020.