In this series, we found strong evidence that cognitive impairments that coexist with anorexia improve with weight restoration, remission, and recovery. But just as we found with the correlations between anorexia and cognitive impairment, there’s some evidence running counter to this broad finding that cognitive benefits can be expected during or after recovery. Here’s a list of the main reviews and individual studies I found suggesting that treatment doesn’t help:

• A systematic review of “Cognitive improvement following weight gain in patients with anorexia nervosa” by Hemmingsen et al. (2021), for instance, found that cognitive flexibility was unaffected after weight gain in children and adolescents, though processing speed was improved, and that results from studies of adults were inconclusive.
• A second systematic review, this time specifically of “Cognitive flexibility in acute anorexia nervosa and after recovery” (Miles et al., 2020), found that studies using within-participants design (comparing performance of the same individual pre- and post-treatment) showed no significant differences in cognitive flexibility between acute and recovered participants (though the conclusions were “limited by a modest number of studies”). For studies using between-participants design (comparing ill participants with healthy controls [HCs]), they concluded that “Recovered participants performed poorer than HCs in some neurocognitive measures, however, results were inconsistent across studies.”
• Tenconi et al.’s (2021) study of “Clinical and cognitive functioning changes after partial hospitalization in patients with anorexia nervosa” found that although decision-making improved significantly after day-hospital treatment, “cognitive monitoring and cognitive inhibition appear to be mostly stable trait-like characteristics.”
• Fürtjes et al. (2018), investigating “Rumination in anorexia nervosa: Cognitive-affective and neuroendocrinological aspects,” found that rumination about food decreased during weight restoration and was correlated with leptin levels, whereas rumination about body weight and shape was not linked to leptin, persisted after weight gain, and showed stronger connections with mood. They conclude that “rumination about body weight/figure seems to be a cognitive-affective aspect of the disorder, but food-related rumination may need to be considered from a physiological perspective.”
• In a stronger challenge to the recovery-improves-things hypothesis, Talbot et al.’s (2014) study “Cognitive deficits as an endophenotype for anorexia nervosa: An accepted fact or a need for re-examination?” found that participants with any lifetime experience of anorexia had worse set-shifting than healthy controls, but that when grouped by illness status, only participants in the two recovered groups (weight recovered and fully recovered) demonstrated worse set-shifting ability than the controls, while “patients with acute AN performed comparably to all other groups.” They conclude that the results are “consistent with a global trend toward set shifting difficulties in patients with AN” but suggest that there may be subgroups of patients who have this type of deficit and others who don’t.
• Even more counterintuitively, Seidel et al.’s (2021) study of “Cognitive function in adults with enduring anorexia nervosa” found that patients with anorexia showed faster reaction times in the attention tasks and increased accuracy in grammatical reasoning compared to healthy controls, and no differences in the other cognitive domains measured, nor any in the sample with anorexia between baseline and follow-up “after weight increase.” They conclude that “These findings supplement results from other studies suggesting increased concentration and reasoning accuracy in patients suffering from AN, who showed increased performance in cognitive tasks despite their illness.”

So what’s going on with these findings that recovery doesn’t help, and maybe even that being ill helps?

Whenever you find something counterintuitive/depressing going on in studies of eating disorders, your best bet is to start by looking at their definitions of remission and recovery. In the next (and penultimate) part of the series, we’ll take a look at how the individual studies and the reviews I’ve cited in this section are defining their key terms, and see what light the definitions can shed on the apparently discouraging conclusion that cognition isn’t improved by recovery.