How to Break the Malnutrition and Mental Function Deadlock

As we wrap up this series of posts on cognitive function in anorexia, the general story so far is that having anorexia could affect how smart you are. The losses take a range of forms encompassing cognitive and emotional capacities, especially affecting mental flexibility: the ability to switch between tasks or perspectives and the ability to see the big picture as well as the details.

Research studies mostly set such a low bar for “recovered” that we can’t confidently compare during- and post-illness performance. Still, the fact that even with such lax criteria, we tend to see improvement in the “post-” groups suggests that you can expect most things to get vastly better with full recovery. That is, where you do find that “recovered” participants get back to parity with healthy controls, this probably means that for real-world purposes, you’ll restore “full cognitive function” (as measurable on these tests) long before full recovery in a sense that is meaningful to you. This may be encouraging, but it may also be one factor that discourages getting beyond “mostly better” or encourages “stopping halfway.” Some isolated bits of evidence show that these impairments are moderately heritable (i.e., that your unaffected sister might share the same pattern). So far, these results could be accounted for by shared environmental influences.

In this final item of my miniseries, we’ll tackle a couple of remaining questions about cause and effect, starting with one that’s been implicit in everything we’ve been investigating so far: How many of the negative effects we see in anorexia are due to semi-starvation alone, and how many need accounting for in some more eating disorder-specific way?

You can’t really separate weight restoration from all the psychological change required and entailed by deliberately gaining weight in a fat-phobic society, so the evidence at the recovery end (i.e., asking what happens when malnutrition is resolved) is too messy to answer this question. Cognitive functioning in eating disorders other than anorexia is certainly impaired differently (e.g., Hirst et al., 2017). But, again, there are too many other differences for us to work out, which are and aren’t attributable solely to malnutrition.

A useful oblique perspective on this question comes from research into the effects of malnutrition amongst older people without eating disorders. Clearly, malnutrition strongly correlates with poor cognitive function (e.g., Sun et al., 2021) and potentially dementia-related measures (Kimura et al., 2019). We can imagine these correlations signifying a causal connection in which poor cognitive function impairs eating habits. But the opposite is also true: Multiple studies indicate that malnutrition drives cognitive impairment, which is, in turn, reversed (Klímová & Vališ, 2018; Allen et al., 2013) or prevented (Solfrizzi et al., 2018; McGrattan et al., 2022) by nutritional interventions of varying kinds.

There are many differences between these populations and those involved in typical studies on anorexia. But the parallel with cognitive decline in older age is a useful reminder that there’s nothing mysterious or glamorous about how a brain fails when the fatty acids, proteins, and all the rest are lacking. The question we’re asking when we ask about the cognitive damage anorexia does is, to a large extent, “What are the cognitive effects of starvation, and are any of them irreversible?” If you’re currently eating too little consistently, your mind will work better once you’re not. As we age, there are great benefits to avoiding the double whammy of malnutrition- and aging-induced damage by getting better while there’s still plenty of time left for repair and regeneration.

So how do you get out? The mind/body/behaviour feedback loops I explored here, which so powerfully get and keep anorexia entrenched, work in reverse too: “Results suggest that enhancing cognitive flexibility could help reduce rigid cognitive and behavioural patterns involved in AN, thus improving everyday functioning and clinical severity” (Duriez et al., 2021).

Getting even a little more flexibility into things cognitively will have knock-on effects on other kinds of flexibility and expansiveness. You just need to break the deadlock somewhere. And normally, the best way to do that is to change something about how you eat. For example, change some behaviours to bring about physical and psychological changes. (For more on the “behaviour first” model of eating disorders and recovery, see Troscianko & Leon, 2020.) That said, anything that gets things shaken up a bit is good; everything that changes even a little bit increases the chances of other things changing, too. So starting at the cognitive end of things can bring benefits if you keep your eye on whether trickle-down into habit change is also occurring.

A few years ago, I wrote a post on “zooming out and back in” as a foundation for recovery and living a good life. Zooming out and in is a crucial real-world application of the central coherence and set-shifting measures of cognitive flexibility, a recurring theme in this series. To build the skills involved in 1) switching between zoomed-out and zoomed-in, 2) linking them meaningfully, and 3) making them the right kind of both requires and generates cognitive flexibility. The skill-building can take wide-ranging forms, from reading sci-fi to getting off your phone to going to places where you can see a distant horizon. If you have something you love to do–or used to, and could bring back into your life–that feels like it demands and allows for widening horizons and agile jumping between frames of reality, whether writing, gaming, painting, making music, or whatever else, cultivate it and help it flow into the meal that follows.

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In the meantime, remember to take any story told by researchers that "x" doesn’t improve with “recovery” with all the appropriate spoonfuls of salt. Beware of how often authors of papers in this field slide between claims of correlation and causation (the term “predict,” which only means correlate with but sounds like it means to cause, is a common offender). Assume it’s only a correlation unless there’s clear evidence to the contrary. And look out for feedback in all its forms–the kinds that can tie you in ever-tighter knots and the kind that can be the long-needed unraveling.

Researching and writing this series, I’ve been aware of seriously testing my cognitive abilities, especially for central coherence or seeing the woods for the trees. Having started out kind of excited by how much research there is on cognitive deficits in anorexia, I end up feeling a little cross about how many resources are being poured into finding out what specific tests people with anorexia and people not properly recovered from it do and don’t do worse on.

It is appropriate to conclude, “Okay, it’s pretty clear that people think better once they get better. Let’s work out how to help that happen more often.” But if that switch seems unlikely to happen in the research, you can make it in your own life and test out the most important hypothesis: This too will be good again once the body that is me has what it always needed.