What is the difference between a Psychiatrist and a Psychologist?

Who is the right expert witness for your case?

Apsychiatrist is a physician and a psychologist holds a doctoral degree but has no medical training.

Before looking for an expert witness appropriate to your case, it’s helpful to consider the distinctions between a psychologist and psychiatrist. It can be confusing. In fact, there are at least 6 types of licensed specialists who assess mental status including psychiatrists, psychologists, neurologists and neuropsychologists. LCSWs and LMFTs sometimes testify though their training and licensing requirements are quite different from psychologists and psychiatrists.¹

A quick summary before we jump in:

• Psychiatrists are medical doctors who, like psychologists, have training in diagnosing and treating mental illness as well as medical training, residency and, generally, Board-Certification in a subspecialty like Psychiatry or Forensic Psychiatry.
• As physicians, the scope and focus of the Psychiatrist’s practice diverges significantly from the psychologist. For example, a psychiatrist can review medical records about all of a person’s medical conditions and and medications, confer with other doctors, and order labs and imaging.
• A psychologist has many hours of training and the focus is primarily clinical including the use of talk and other therapies to help their clients achieve better mental health.
• Both psychiatrists and psychologists can achieve Board-Certification in the forensic application of their specialization and serve as an expert witness.

Any Expert Witness can be disqualified if their findings steps outside their area of expertise. That’s why it is so important that the expert witness’ qualifications are relevant to the case.

For example, a plaintiff who has two medical conditions like diabetes and anxiety, takes multiple medications for these conditions and experiences side effects. The psychiatrist is the appropriate expert witness. These are complicated medical conditions. A psychologist is not qualified to address medical treatment.

Alternatively, a Plaintiff claims a causal link between a car accident and debilitating anxiety. If there are no other medical considerations, either a psychologist or psychiatrist might be able to testify.

That’s the simple answer, but not a complete one.

Serving as an Expert Witness requires the expert testify within the confines and scope of their credentials and experience. The line is real. Let’s dig in.

Many litigants and even some attorneys I have worked with address a “Dr.” as if the designation following their name means the same thing.

That is not the case.

MDs and DOs are licensed physicians.

PhDs and PsyDs are psychologists.

All carry distinct legal and clinical considerations and limitations.

Psychiatrists are Physicians

A psychiatrist is a licensed medical doctor that can diagnose mental disorders including substance use disorders and prescribe medications. A licensed psychiatrist’s name may be followed by “M.D” or “D.O.” D.O. stands for Doctor of Osteopathic Medicine which reflects the same training as an M.D. including attending medical school, completing internship and a 4 year residency program. ² A psychiatrist can order and interpret labs and imaging such as a Brain MRI. Some psychiatrists provide psychotherapy. Psychiatrists perform limited psychological testing like the Mental Status Exam (MSE) which helps identify cognitive deficits such as symptoms of dementia. However, a neuropsychologist has dedicated training in advanced psychological testing, discussed below. Psychiatrists complete medical school where they are exposed to all the medical specialties from surgery to radiology. They also learn about anatomy, physiology, pharmacology, and other disciplines. After medical school, they complete a four-year psychiatry residency which includes rotations in Internal Medicine, Neurology as well as, of course, Psychiatry.  The exposure to psychiatry training is varied and includes inpatient, outpatient, consult (medical hospital), addictions, child, and possibly geriatric settings. A psychologist does not have medical training, but has years of experience diagnosing and treating mental illness. Licensing has rigorous requirements for psychologists in most states.

Credentials that Matter. Board-Certification in Forensic Psychiatry and Forensic Psychology

Both psychiatrists and Psychologists can achieve Board-Certification in a subspecialty including Forensic Psychiatry or Forensic Psychology. In the case of a psychiatrist, the American Board of Psychiatry and Neurology grants Board-Certification after a physician completes a qualifying intensive year-long fellowship in Forensic Psychiatry and passes the Board examination. After a psychiatrist completes residency, they may sub-specialize in one of 18 psychiatry and neurology areas of practice  recognized by the ABPN, including

• Forensic Psychiatry
• Brain Injury Medicine
• Child and Adolescent Psychiatry
• Pain Medicine

Forensic Psychiatry Board-Certified Doctors

Forensic Psychiatry is a unique sub-specialty “in which scientific and clinical expertise is applied in legal contexts involving civil, criminal, correctional, regulatory, or legislative matters, and in specialized clinical consultations” (American Academy of Psychiatry and the Law). A one-year fellowship is required to obtain Board Certification in Forensic Psychiatry with the American Board of Psychiatry and Neurology. Fellows are licensed physicians. Fellowship includes practical experience in correctional psychiatry and, in most cases, other areas of criminal and civil law. Fellows perform medico-legal evaluations and give testimony. They may serve as expert witnesses. Didactics include training about the legal system and landmark cases. There are about 50 Forensic Fellowships in the United States and they accept 2-4 candidates each year. According to the ABPN, fewer than 1500 psychiatrists are currently actively Board-Certified in Forensic Psychiatry. As a result, Board-Certified Forensic Psychiatrists typically have more experience in performing detailed evaluations, writing reports about their conclusions and testifying than clinical Psychiatrists who practice in a treatment setting.

A Psychologist’s Training, Licensing and Board-Certification

A licensed psychologist with a PhD or PsyD has completed lengthy post-graduate training and committed hundreds-to-thousands of hours in supervised internship. They must then pass oral and written exams and obtain licensing in their given practice State. Generally, the focus of a PsyD program is clinical, i.e. patient-care. PhD psychology programs generally focus on research and academia, but many Psychologists who hold a PhD treat patients. Either can serve as an expert witness if they have the applicable expertise. In Texas, a licensed psychologist with a PhD or PsyD completes 1,750 hours in internship, and must pass the Examination of Professional Practice in Psychology as well as a Jurisprudence Examination.³ Similar requirements are found in most States, though examination about jurisprudence is not universal. A psychologist has not attended medical school, completed a residency or passed any medical examination. They are not licensed to practice medicine. Psychologists receive training in diagnosing mental disorders, psychological testing, and providing psychotherapy. Except in a few states in limited circumstances, psychologists do not prescribe medicine. They do not receive training to interpret brain imaging or labs and are not qualified to do so. Psychologists can pursue additional education to become a Forensic Psychologist, which deals with the interface between psychology and the law. Fewer than 350 ABPP Board-Certified psychologists are Board-Certified in the Forensic Psychology subspecialty.

Is a Psychiatrist the Appropriate Expert?

Many cases will require a psychiatrist because, in my experience, medical history is a relevant context for the results of my IME and the conclusions in my report. That is not always the case.

Example: Traumatic Brain Injury Case

Because I deal with brain-injured patients and am Boarded in Brain Injury Medicine, I have served as an expert witness in cases where someone alleges a brain injury or a dementia is a relevant factor. I might review neuroimaging and confer with a neurologist including doctors treating the examinee/litigant/defendant. In this example, the psychologist is not qualified to review neuroimaging or confer with the neurologist about a medical matter. However, a psychologist can perform neuropsychological testing or confer with a neuropsychologist about the cognition of the examinee. For example, a brain injury can result in cognitive issues which are measured with tests of memory, attention, learning deficits and more. These are administered and interpreted by a psychologist or neuropsychologist.

Case Study: Liver Failure and Delirium

The medical experience of a physician was absolutely necessary for an interesting case study about Competency to Stand Trial and liver failure described on this site. Delirium can be a symptom of a psychiatric condition, Dissociative Disorder. In theory a psychologist is trained to treat Dissociative Disorders. In this case, however, the delirium was attributable to medical sequelae of a failed liver in a man who was not a candidate for an organ transplant. An attorney who is uncertain about whether the symptoms are delirium or Dissociative Disorder, and who is the right expert, will need a psychiatrist to first review the records. In this case, I found a medical cause of a psychological condition. A psychologist is not trained or qualified to make such an assessment. If Dissociative Disorder was the only condition present, a psychologist might be able to make the forensic assessment.  However, Dissociative Disorder is primarily treated with medication and, as stated, in most States a psychologist is not licensed to prescribe. Had a diagnosis been issued by a licensed Psychologist it could easily be challenged as being outside the expert’s qualifications. Legal matters may benefit from having both a psychiatrist and a psychologist.  Occasionally, there are cases when a psychologist is better suited.

I have been asked about the differences between other medical and non-medical experts, or complementary or ancillary specialists. It can be confusing, as is the came with Neurology vs. Neuropsychology .

How Is a Neurologist Different From a Neuropsychologist?

I am sometimes asked to explain seemingly similar specializations, like the distinction between a neurologist and a neuropsychologist.

A neurologist is a physician who treats conditions of the brain, spinal cord, and nervous system. They are Board-Certified by the American Board of Psychiatry and Neurology.

Unlike a psychiatrist or neurologist, a neuropsychologist does not diagnose or treat mental illness associated with a medical condition. They may, however, treat conditions that affect mood, behavior and emotional regulation. For that reason neurologists and psychiatrists sometimes both serve as expert witnesses. For example, consider a situation where a person has a brain lesion and clinical depression. Did either or both influence a decision such as signing a will or making a financial gift? I have seen expert witnesses issue opinions that are not within their qualifications. In a will contest case, for example, it is not always obvious.

Psychiatrists with additional Board-Certification in Brain Injury Medicine treat psychiatric conditions associated with, for example, dementias, TBI, mTBI, stroke or spinal cord injuries and conditions. I work in this environment at TIRR Hermann.⁴ BIM-Boarded Psychiatrists are not neurologists but may work with the same patients, who are also being treated by a neurologist.

Note: Board-Certification in Brain Injury Medicine and Forensic Psychiatry are granted by the ABPN which Board-Certifies Psychiatrists and Neurologists.

What is a Neuropsychologist?

Neuropsychologists assess cognitive functioning and document performance and/or deficits through the use of testing and assessment tools.

Psychiatrists are generally not qualified to perform these tests or interpret them.

For example, if an examinee might have learning, memory, or other deficits, a psychiatrist might work with a neuropsychologist to clarify the examinee’s brain functioning.

Neuropsychologists are psychologists who have received subspecialty education in performing detailed neurocognitive testing using a range of assessment tools.  It is difficult to become Board-Certified in Neuropsychology, given the additional years of education and practice with a range of tools (tests) that provide measurable data and meet high scientific standards.⁵

Summary: Civil Lawsuits, Crime, and Human Behavior

Why people do the things they do is a complicated subject. There is no question that all of the specialists described here, Psychiatrists, Psychologists, Neurologists and Neuropsychologists have received education about the brain and its role in how a person chooses to act.

These specialties are not interchangeable but there are overlaps.

Psychiatrists and Psychologists diagnose and treat mental illness. Neurologists address the nervous system and injuries or diseases of the brain. Neuropsychologists measure a person’s brain function and identify if there are issues that might influence behavior.