The Clock Drawing Test

Simplicity at its finest

This past winter break, at the urging of my best friend, I read “Brain on Fire” by Susannah Cahalan (depicted in the photo at the top of the blog). Although I normally try and steer clear of popular psychology books, mostly because while reading them I find myself critiquing almost every conclusion they draw, I only had to read one chapter before I was hooked. In this novel, 24-year-old Cahalan tells the story of her “month of madness” spent in the hospital struggling with an illness that doctor after doctor could not diagnose. After numerous seizures, she is rushed to the hospital by her parents, where her life is slowly consumed by psychosis and paranoia. Her motor skills progressively worsen to the point that she can barely walk, and her speech becomes fully incomprehensible. Countless blood test, spinal taps, and other medical exams later, the neurologists treating her prove incapable of providing a diagnosis. Just when all hope seems lost, Dr. Souhel Najjar, a neurologist from New York University, visits Cahalan in the hospital and administers a single test: the Clock Drawing Test. The results of this test mark a distinct turning point in her illness; from here, Dr. Najjar suggests a brain biopsy, which leads to a diagnosis of anti-NMDA receptor autoimmune encephalitis. Cahalan spends the rest of her novel documenting her almost two-year long recovery and eventual return to her position as a journalist.

So what exactly is the Clock Drawing Test, and what did it tell Dr. Najjar that enabled him to essentially safe Cahalan from a downward spiral of psychosis? The Clock Drawing Test asks a participant to do one simple task: draw a clock that displays the time “ten after eleven”. In comparison to the other psychological test we’ve looked at in class, this one is remarkably uncomplicated and seemingly basic. Yet it provides a vast amount of guidance to any clinician attempting to diagnose a patient displaying a variety of neurological symptoms. When the test was administered to her, Cahalan was successful in drawing a circle with all twelve numbers. The part about her response that was unique is that she squished all of the numbers on the right side of the clock, rather than distributing them equally around the entire circumference. From this, Dr. Najjar was able to conclude that her right hemisphere was inflamed, and after examining similar case studies from elsewhere in the United States, gave a diagnosis and started treatment.

I think the reason that I find the Clock Drawing Test so compelling is that it acts as an incredibly useful screening test for those displaying symptoms that could be related to a neurological illness. Patients with hemineglect will draw a very different clock from those with dementia. I often wonder if such a test will ever exist for psychiatric disorders. Are we ever going to be able to ask patients with schizophrenia and bipolar to do something that seems very simple, and observe a profound and telling difference? Are we too busy looking at microscopic details that we miss a bigger picture of these disorders? Perhaps one day these screening tests will exist, but for now I think the field of psychiatry is far from finding a neat answer to distinguish between these and other disorders. In the meantime, I will continue to be astounded by the simplicity, power, and genius that is the Clock Drawing Test.