The Frontal Assessment Battery (FAB) and its sub-scales: validation and updated normative data in an Italian population sample

Background Deficits of executive functioning (EF) are frequently found in neurological disorders. The Frontal Assessment Battery (FAB) is one of the most widespread and psychometrically robust EF screeners in clinical settings. However, in Italy, FAB norms date back to 15 years ago; moreover, its validity against “EF-loaded” global cognitive screeners (e.g., the Montreal Cognitive Assessment, MoCA) has yet to be tested. This study thus aimed at (a) providing updated normative data for the Italian FAB and (b) assessing its convergent validity with the MoCA. Methods Four-hundred and seventy-five healthy Italian native speakers (306 females, 169 males; mean age: 61.08 ± 15.1; mean education: 11.67 ± 4.57) were administered by the MoCA and the FAB. FAB items were divided into three subscales: FAB-1 (linguistically mediated EF), FAB-2 (planning), and FAB-3 (inhibition). Regression-based norms were derived (equivalent scores) for all FAB measures. Results Age and education were predictive of all FAB measures, whereas no gender differences were detected. The FAB and its sub-scales were related to MoCA measures—the strongest associations being found with MoCA total and MoCA-EF scores. FAB sub-scales were both internally related and associated with FAB total scores. Discussion The FAB proved to have convergent validity with both global cognitive and EF measures in healthy individuals. The present study provides updated normative data for the FAB and its sub-scales in an Italian population sample, and thus supports an adaptive usage of this EF screener. Supplementary Information The online version contains supplementary material available at 10.1007/s10072-021-05392-y.


Introduction
Executive functioning (EF) comprises a multifaceted set of frontally mediated, noninstrumental cognitive processes that control instrumental domains and behavior [1]. Executive disorders are thus frequently found in a variety of neurological conditions of different etiologies that affect cortical/ subcortical frontal structures [2].
Although second-level specific psychometric tests are to be preferred when assessing EF [3], screening instruments for executive deficits are often useful in clinical settings, such as providing with an optimal trade-off between informativity and both sensitivity and a rapid administration [4].
The FAB is one of the most widely used EF screeners worldwide; its psychometric properties, clinical usability, and neural correlates have been thoroughly investigated [7].
In Italy, the FAB has been adapted and normed, as well as validated in both healthy and clinical populations [6,8]. However, current FAB Italian normative data date back to more than 15 years ago and sociodemographic changes require norms updating [9]. Moreover, to the best of the authors' knowledge, the FAB has been only validated against "non-executive" screeners in Italy [6]-e.g., the Mini-Mental State Examination (MMSE) [10]-whereas its association with "EF-loaded" screening measures, e.g., the Montreal Cognitive Assessment (MoCA) [11], has yet to be explored. In addition, FAB normative studies do not provide with norms for its subtests, despite this being an increasingly widespread approach for cognitive screeners in Italy [12,13], as it allows greater flexibility for clinicians when using these instruments. Accordingly, the two aims of the present study are (1) providing updated normative data for both FAB total and sub-test scales in a large Italian representative population sample and (2) validating the FAB and its subscales against the MoCA.

Participants
The sample consisted of N = 475 healthy Italian native speakers from different provinces of Northern Italy (Table 1). Participants had no history of neurological, psychiatric, or severe general medical conditions (i.e. severe internal and metabolic morbidities or systemic/organ failures). Studies that data come from were approved by the Research Evaluation Committee of the Department of Psychology of University of Milano-Bicocca on behalf of the Ethical Committee of the same university. Participants provided informed consent to participation and signed a data treatment disclaimer research purposes.

Materials
Global cognition was assessed via the MoCA [12,14], which encompasses subtests evaluating EF (MoCA-EF), attention  Table 1 provides the protocol for the current FAB. FAB items (N = 6) were grouped into 3 subscales: FAB-1 comprising the first two items (similarities and phonemic verbal fluency, linguistically mediated EF); FAB-2, comprising the second two-item set (Luria motor sequences and conflicting instructions, planning); FAB-3, comprising the last two items (go-no-go and prehension behavior, inhibition). All participants were administered the MoCA first and then the FAB.
Associations of interest between quantitative variables were assessed by means of either Pearson's or Spearman's techniques. When judged as relevant, Bonferroni correction for multiple comparisons was applied.
Analyses were performed via SPSS 27 [22] and R 3.6.3 [23]. Regression studies, as well as computations of both TLs and ES thresholds, were implemented according to guidelines and software solutions described in [24].

Results
Background and cognitive scores are summarized in Table 2.
Selected correction factors and adjustment equations for FAB total and subtest RSs are displayed in Tables 4 and 5, respectively. TLs and ESs classifications for all FAB ASs are reported in Table 6.

Discussion
The present work provides Italian practitioners with updated normative data for the FAB and its subtests. These norms cover a wider age and education range and are drawn from a larger sample size (N = 475) than those of previous normative studies (N = 236 [8] and N = 364 [6]). Moreover, norms for FAB subscales are provided-this representing a previously unreported feature that supports an adaptive usage of the screener. This study overall replicates previous findings with respect to the range of FAB scores' predictors in the Italian population: the performance increases with higher educational attainment and decreases with aging, while no sex differences are detected [6,8]. It has nonetheless to be noted that the cutoff reported here (12.03), despite being similar to that derived by Iavarone et al. [8] (11.54), is more conservative than Appollonio et al.'s [6] (13.5). This aspect might reflect sociodemographic changes that have occurred in the last two decades in northern Italian population.
To the best of the authors' knowledge, this contribution is the first showing convergent validity between the FAB (and its sub-scales) and an "EF-loaded" cognitive screeneri.e., the MoCA-in Italian healthy individuals. The present results also support the notion of the MoCA being a screening instrument sensitive to EF deficits, when compared to other screeners, such as the MMSE [25].
Funding Open access funding provided by Università degli Studi di Milano -Bicocca within the CRUI-CARE Agreement.
Data Availability Data collected and analyzed during the present study are available on the Open Science Framework (OSF) repository (https:// osf. io/ 4xypv/).

Declarations
Ethics approval This study was conducted in accordance with the Declaration of Helsinki. Participants provided their informed consent to participation.

Conflicts of interests
The authors declare no competing interests.
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