The Utility of Neuropsychological Testing

TCPR: To begin, Dr. Woo, what sort of training does a neuropsychologist have?

Dr. Woo: A clinical neuropsychologist has a PhD in psychology as well as at least two years of specialized training.

TCPR: Many psychiatrists have had the experience of referring a patient for neuropsych testing, only to end up with a very long report that doesn’t clearly add much of value to the assessment. Can you describe a case in which neuropsych testing made a real difference?

Dr. Woo: Sure. I was referred a 21-year-old man with schizophrenia, who had been admitted to the hospital for difficulties with functioning and bizarre delusions. Before admission, he was in college and was doing well there. After his discharge, he was referred to a partial hospitalization program, where he complained of concentration and memory problems, and he was referred to me to come up with a cognitive profile and to make treatment recommendations.

TCPR: Can you describe in detail what you did during the testing?

Dr. Woo: I always start by orienting the patient to the process. I usually say something like, “It sounds like you’ve been having some problems with concentration and memory, and sometimes these problems can be due to emotional or neurological issues. My job today is to help sort this out. I’m going to ask you some questions, then give you a series of tests, mostly paper and pencil. Afterwards, I’ll prepare a detailed report for you and your doctor.”

TCPR: This sounds like a nice way for psychiatrists to describe the process to our patients so that they will accept the referral — not always an easy task! What do you do next?

Dr. Woo: I then do a generic clinical diagnostic interview, focusing on DSM-4 diagnostic criteria. What distinguishes this from the usual diagnostic interview is that I am probing for neuropsychological hazards, such as history of head injuries, toxin exposure, epilepsy, and other factors.

TCPR: How do you decide which tests to give patients?

Dr. Woo: In the past, there was a standard neuropsychological battery that all patients would receive. This tended to be a very long, exhausting process for the patient. These days, most neuropsychologists use a more flexible approach, sometimes called the Boston Process Approach. This means coming up with diagnostic hypotheses and then choosing tests that are most appropriate for answering certain questions.

TCPR: So it’s no longer an 8 hour marathon session?

Dr. Woo: No, usually it takes 3 to 3 1/2 hours. After the diagnostic interview, I’ll start with the Mini Mental Status Exam, because it’s quick and easy for the patient. Then I gradually build up to harder tests. In general, I’m interested in assessing six distinct areas of functioning: attention; higher cognitive function (also known as executive function); language; memory; visual and perceptual function; and emotional and personality function. I’ll pick and choose among many different tests, depending on the patient.

TCPR: Let’s talk about what you did with the young man with schizophrenia you described.

Dr. Woo: Initially, I asked him about his goals. He said he wanted to go back to school, develop friendships and find a girlfriend. I then picked tests that I knew he would be willing to do. I started with tests of passive attention such as counting digits, reciting the alphabet, and reciting days and the week. I then built up to more participatory tasks like the Trail Making Test.

TCPR: What is the Trail Making Test?

Dr. Woo: Patients have to connect dots, first going from numbers to numbers, then in sequence from numbers to letters to numbers. For example, you would have to connect the sequence: 1, A, 2, B, 3, C, and so on. I found that he could not easily main- tain the sequence, and I had to redirect him a lot. This implied that he had difficulty with sustained attention and sequential processing.

TCPR: Lately, we have been in the psychiatric literature that patients with schizophrenia have well-defined cognitive impairments, even after their acute psychotic symptoms are stabilized [see Keefe RS and Fenton WS, Schizophrenia Bulletin 2007 33(4):912-920]. Is this a common cognitive deficit?

Dr. Woo: Yes, a problem with sustaining attention is a well-established impairment in schizophrenia, and my testing showed that his degree of impairment was consistent with his diagnosis. I then moved on to testing higher cognitive processes, like planning and organization—also often impaired in schizophrenia. I started by giving him a constructional task, the Rey-Osterrieth Complex Figure recall task. This involves copying a complex figure, and he had significant problems with planning and organizing the drawing. The normal way to draw the figure is to start with the overall design and then attend to the details. But he started with the details, with the result that the drawing was disproportionate.

TCPR: Did you do any other tests of executive function?

Dr. Woo: Yes, I gave him the Wisconsin Card Sort—a test of nonverbal problem solving ability and frontal lobe functioning. I laid out four cards face up with different colors and shapes, and I gave the patient a stack of cards. The task is to take a card from the stack and put it on top of the card that has the best match. I didn’t tell him the matching rule, just whether the choices he made were correct or not, so he had to figure out the rule as the task progressed. It gets even harder, because the matching rule changes during the task without the patient knowing. His score fell into the impaired range, showing reduced cognitive flexibility.

TCPR: And what about memory testing?

Dr. Woo: I tested his memory in a couple of ways, using items from the Wechsler Memory Scale. I read him two stories, and had him summarize them for me both immediately and after 30 minutes. His immediate recall was impaired, meaning he never learned the stories. This implies that he would have a very difficult time sitting in a lecture hall and learning the material without substantial preparation. Again, this is common in schizophrenia, a problem with verbal or semantic memory. I gave him another test to evaluate his ability to learn with practice. I read him a list of words to repeat, and I re-read the list three more times. He scored in the Average range, and had a positive learning curve, showing that he could learn well with repetition. This was encouraging, because often antipsychotic medication can interfere with learning in schizophrenics, and in this case he was able to overcome this.

TCPR: So what were your recommendations based on the neuropsych testing, and what did your testing add that his treaters didn’t already know?

Dr. Woo: The staff at his partial hospitalization program were telling him that he would have to give up college for the foreseeable future, because they were overestimating the degree of his cognitive impairment. My testing revealed that he still had quite a few strengths, including good intelligence, and good language ability, and the reality is that some patients with schizophrenia can often go back to school. So based on the testing, I gave him some specific suggestions. Because of his verbal memory deficits, I suggested that before he goes to a lecture he should read the material ahead of time, and then use the lecture to provide him with memory cues to retrieve the information. And because of his problems with organization and cognitive flexibility, I recommended he use the same routine every day, to reduce demands on his daily cognitive function. I also asked him to develop an written organization system that he will be successful with, and I referred him to a speech-language pathologist for cognitive re-training to help him with this process. This is often how I find testing helpful for patients — it helps them to create a world around themselves in which they can be successful.

General Psychiatry

KEYWORDS diagnostic_testing