Identifying ME/CFS from a common mental health questionnaire

ME/CFS is often misdiagnosed as depression — for one very obvious reason

If you think you aren’t familiar with the PHQ-9, you’ll probably recognize the questions when you see them. In recent years, doctors have started administering it as a standard element of primary care visits, as a way to quickly screen patients for common symptoms of depression.

Photo by Scott Graham on Unsplash

The PHQ-9 measures how frequently a patient has experienced nine symptom groups in the past two weeks, on a scale of 0 (not at all) to 3 (nearly every day):

1. Little interest or pleasure in doing things
2. Feeling down, depressed, or hopeless
3. Trouble falling or staying asleep, or sleeping too much
4. Feeling tired or having little energy
5. Poor appetite or overeating
6. Feeling bad about yourself — or that you are a failure or have let yourself or your family down
7. Trouble concentrating on things, such as reading the newspaper or watching television
8. Moving or speaking so slowly that other people could have noticed? Or the opposite — being so fidgety or restless that you have been moving around a lot more than usual
9. Thoughts that you would be better off dead or of hurting yourself in some way

There’s typically a final item that allows the patient to indicate how much difficulty they’ve had at work, home, & in interpersonal relationships due to any of the above symptoms, from none to extreme difficulty.

It’s easy to score; the provider simply adds up the numbers given for each numbered item, for a total of between 0 and 27. Per the University of Washington, a score of 0 to 4 indicates no or minimal depression; 5 to 9 indicates mild depression; 10 to 14, moderate; 15 to 19, moderately severe; 20 and up, severe.

The trouble is, in a primary care context, the answers to some of the PHQ-9 items may indicate an underlying disease process, not simply depression. Despite this, the PHQ-9 continues to be used as simply a depression screening tool, possibly contributing to frequent misdiagnoses of depression among chronically ill & neurodivergent patients.

As someone who likely has ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome) but has yet to find a physician who will diagnose it, I’ve noticed a pattern in my PHQ-9 responses when my ME/CFS is more active. I’ve learned to think carefully about how I answer this questionnaire during flares to avoid being flagged as severely depressed when I’m simply ill.

Questions referencing core symptoms lead the PHQ-9 to indicate moderate to severe depression in ME/CFS patients

On an objective level, there’s significant overlap between core ME/CFS symptoms and certain PHQ-9 items, most notably items 3 (sleep disruptions), 4 (feeling tired or having little energy), 7 (trouble concentrating), and 8 (moving or speaking slowly)— these are defining symptoms of ME/CFS. When I’m in a ME/CFS flare, the most honest answer I could give to each of these items is 3, for a total of 12 points on those 4 items.

Item 5, specifically poor appetite, is also common in ME/CFS — dizziness & nausea aren’t core symptoms, but many patients experience them. The remaining 4 items often occur as a result of the activity restrictions inherent to ME/CFS — a large portion (perhaps a majority) of ME/CFS patients have considered suicide (item 9). The experience of not being able to do the things you enjoy is in itself enough to trigger feelings of hopelessness & a sense that you’re a failure or you’ve let your family down (items 2 & 6).

I’d call the ME/CFS PHQ-9 profile a “spiky” one. In active ME/CFS, the patient will likely give a very high rating to items 3, 4, 7, & 8, a moderate rating to items 2, 5, 6, & possibly 9.

And this brings me to item 1 — little interest or pleasure in doing things. I’d call this one a toss-up. In some ME/CFS patients, the interest/pleasure in doing things we love doesn’t go away. We find ways to adapt pleasurable activities to meet our physical needs — for example, I’m able to write using my laptop in bed or my recliner. Some of us have made documentaries about the illness.

The PHQ-9 needs to address the overlap between symptoms of physical & mental health conditions.

When ME/CFS patients have reliable support networks, items 1, 2, 6, & 9 will often have significantly lower ratings than items 3, 4, 5, 7, & 8 (common ME/CFS symptoms). Still, the questions referencing core symptoms lead the PHQ-9 to indicate moderate to severe depression in ME/CFS patients if we answer honestly.

So, what’s the solution when one of the most widely used mental health assessment tools will, predictably and consistently, lead providers to misdiagnose depression in ME/CFS patients — and, if their PHQ-9 total is over 20, immediately initiate psychopharmaceutical treatment that could worsen the patient’s physical condition?

The PHQ-9 needs to address the overlap between symptoms of physical & mental health conditions. The simplest fix may be dividing the PHQ-9 into 3 clusters that receive separate scores —physical (items 3, 5, & 8), emotional (items 1, 2, & 6), & cognitive (items 4, 7, & 9). Something more precise could be determined through a scientific study comparing PHQ-9 scores of patients with only depression to patients with ME/CFS & other energy-limiting chronic illnesses.

Each cluster would be scored from 0 to 9, allowing simple comparison of symptom clusters. ME/CFS patients would typically score very high on the physical cluster, high on the cognitive cluster, and comparatively lower on the emotional cluster. This may open up the opportunity to provide more accurate provisional diagnoses than simply “depression” based on PHQ-9 scores per cluster and provide an easier pathway to evaluation and diagnosis for various conditions with neurocognitive manifestations.

As of 2017, a majority of ME/CFS patients who were diagnosed at all needed to see four or more physicians before being diagnosed.

With long COVID triggering more cases of ME/CFS every day, and with ME/CFS itself making healthcare access a huge challenge, it’s vital to recognize patients experiencing its core symptoms as soon as possible, before they crash any further & possibly lose the capacity to attend healthcare appointments at all.

If nothing else, patients in that situation deserve to have their reality acknowledged in their medical records. As it stands, if a ME/CFS patient stops making or showing up for appointments after one or two elevated PHQ-9 scores, their record would lead most healthcare providers to assume they stopped showing up due to depression, not severe illness.

As of 2017, a majority of ME/CFS patients who were diagnosed at all needed to see four or more physicians before being diagnosed. Few of us have the capacity, physical or financial, to go to such lengths for something as basic as an accurate diagnosis — and providers often accuse those who can of “doctor shopping”.

Healthcare providers need to, and can, do better for us — they can start by listening to those of us who can still get our voices out into the world.