If We Can Detect Cognitive Impairment Six Years Before Alzheimer’s Diagnosis…What About Pre-Delirious Syndromes?

I just read an intriguing story in the latest issue of Psychiatric News about a large prospective study showing that sharply declining cognitive function can be identified five to six years before Alzheimer’s disease is diagnosed[1]. See the link, http://pn.psychiatryonline.org/content/46/9/18.2.full. The study included over 2,000 subjects in their late 70s who at baseline didn’t have Alzheimer’s or any other dementia. The evaluation included neuropsychological testing as well as a medical history, and a neurological exam. They were examined annually until the study ended 16 years later. During follow-up, 462 subjects were diagnosed with Alzheimer’s disease. In the five or six years preceding the diagnosis, neurocognitive testing revealed an accelerating decline in semantic memory, working memory, perceptual speed, visuospatial ability, and episodic memory.

The implications for early detection of delirium in hospitalized older patients is evident. I’ve written previously about early detection of delirium. Recall the Beglinger et al study which demonstrated early detection of cognitive slippage before frank delirium developed in bone marrow transplant patients[2]. Their recommendation was to add Reversible Battery for the Assessment of Neuropsychological Status (RBANS) subtests to delirium screening tools, one of them the Coding task; see shortlink  http://wp.me/p1glcu-ak . I have gone round and round about this with our delirium project for months. One of the barriers to implementing the strategy is finding someone who would be willing and able to do it consistently. We put high expectations on nurses routinely to do all of the screening for delirium, but they’re not keen on administering a neuropsychological test which would need to be interpreted by a neuropsychologist anyway. And can you blame them? I outlined the challenges in implementation in a post, http://wp.me/p1glcu-hR:

And what would be the consequences of deciding to add an RBANS subtest (e.g. Coding) to delirium screens? Questions would include but not be limited to:

1. To which delirium screening scale would it be added?

2. Who would administer the test?

3. How long would it take to administer?

4. How often should it be administered?

5. Who would interpret the results?

6. What would be the intervention for an abnormal result?

7. How much would it cost?

Probably the main consideration about item 1 would be time to administer the delirium instrument. The Nu-DESC might have an edge since it reportedly takes only about a minute. That might also take care of the criticism that it lacks an item for assessment of attention. I’ve been told that the Coding test takes about 5 minutes to administer.

Regarding item 2, I’ve been assured that nurses could be trained quickly to administer the Coding test.

About item 3: I’ve been told Coding takes about 5 minutes to administer.

For item 4, the test should be done on admission to obtain a baseline value although how frequently it’s done after that could be debated, especially since screens like the Nu-DESC are done every shift. It’s possible that practice effects might make running the Coding test as frequently as every shift might make it less sensitive.

Item 5 probably gives us a negotiation issue which might become a difficult conversation. Nurses could rightfully say that neuropsychologists should be accountable for calculating z-scores and comparing them to norms in order to interpret abnormalities. But just for the sake of discussion, say nurses were comfortable doing these operations. What then? The results would need to be reported immediately to the primary physician, who will have to act on the information regardless of who reports it.

And so for item 6, what would be the intervention for an abnormal result? Here, we need to specify what “abnormal” means. That’s not a problem for the Coding test because there are clear norms. But what if you got a normal delirium screen result and an abnormal Coding test result? The other way around is less problematic. You might try to make the argument that you should trust the Coding test result. Then why do the delirium screen at all? This might have to be a consensus agreement that stakeholders would have to reach before going live. But say you get that done and the Coding result is abnormal. The patient is not clearly delirious and the patient is not yet clearly delirious…yet. Well, that would trigger a concerted search for any reversible medical causes of delirium. Note that I did not mention calling the psychiatric consultant as the first maneuver. Non-pharmacologic multicomponent strategies would probably be applicable first. These would be the usual search for metabolic problems, getting rid of unnecessary drugs, making sure the patient gets enough sleep, has sensory aids available, and so on. The treatment team might consider whether or not to try using scheduled low dose antipsychotic if the multicomponent method is ineffective. The devil’s in the details at this stage.

Item 7 is pushed to last, which you could expect from a physician who doesn’t typically think about money before patient welfare. RBANs tests are not free and neither is a neuropsychologist’s time. Can you afford not to spend a little money on preventing delirium?

Neuropsychologists are in short supply in any hospital and they’re always busy. On the other hand their role as a critical part of a Psychosomatic Medicine service trying to develop a delirium prevention program for hospitalized older persons is increasingly clear. My ideal Psychosomatic Medicine service would include a neuropsychologist.

Those are my thoughts. What are yours?

1.    Arehart-Treichel, J., Dramatic Cognitive Decline Seen Years Before Alzheimer’s Diagnosis, in Psychiatric News. 2011, American Psychiatric Association: Arlington, VA. p. 1.

2.    Beglinger, L.J., et al., The neuropsychological course of acute delirium in adult hematopoietic stem cell transplantation patients. Arch Clin Neuropsychol, 2011. 26(2): p. 98-109.