Motor Imagery as a Key Factor for Healthy Ageing: A Review of New Insights and Techniques

Motor imagery (MI) describes a dynamic cognitive process where a movement is mentally simulated without taking place and holds potential as a means of stimulating motor learning and regaining motor skills. There is growing evidence that imagined and executed actions have common neural circuitry. Since MI counteracts cognitive and motor decline, a growing interest in MI-based mental exercise for older individuals has emerged. Here we review the last decade’s scientific literature on age-related changes in MI skills. Heterogeneity in the experimental protocols, as well as the use of populations with unrepresentative age, is making it challenging to draw unambiguous conclusions about MI skills preservation. Self-report and behavioural tasks have shown that some MI components are preserved, while others are impaired. Evidence from neuroimaging studies revealed that, during MI tasks, older individuals hyperactivate their sensorimotor and attentional networks. Some studies have argued that this represents a compensatory mechanism, others claim that this is a sign of cognitive decline. However, further studies are needed to establish whether MI could be used as a promotion factor to improve cognitive functioning and well-being in older people

Neurofunctional reorganization to support semantic processing during aging : an fMRI study

Le langage est dans son ensemble bien préservé pendant le vieillissement (Meyer & Federmeier, 2010) tandis que la mémoire sémantique peut même s'améliorer (Kavé, Samuel-Enoch, & Adiv, 2009; Prinz, Bucher, & Marder, 2004; Salthouse, 2009; Verhaegen & Poncelet, 2013 ; Wingfield & Grossman, 2006), malgré de nombreux changements neurophysiologiques se produisant dans le cerveau (Grady, Springer, Hongwanishkul, McIntosh, & Winocur, 2006 ; Kemper & Anagnopoulos, 1989 ; Wingfield & Grossman, 2006). Cette thèse se concentre sur la préservation de la mémoire sémantique dans le vieillissement, « l'acte cognitif d'accéder aux connaissances stockées sur le monde » (Binder, Desai, Graves et Conant, 2009) à travers une tâche de jugement sémantique manipulant le contrôle sémantique avec deux niveaux de demande (faible et élevé) et deux types de relations sémantiques (taxonomique et thématique). Nous avons développé une nouvelle tâche variant les niveaux de demande (faible et élevé) chez 39 adultes jeunes et 39 adultes âgés. Plus précisément, les objectifs de notre étude étaient 1) d'identifier si le vieillissement affecte l'activité cérébrale liée à la mémoire sémantique conformément aux prédictions du modèle CRUNCH, à travers une tâche de jugement sémantique à deux niveaux d'exigences. 2) de combler le vide de la littérature sur l'existence et l'évolution des hubs sémantiques dans le vieillissement, à la lumière des théories single hub et dual-hub, en évaluant l'effet du vieillissement sur le rôle des lobes temporaux antérieurs (ATL) et du jonction temporo-pariétale (TPJ) en tant que représentations neuronales des centres sémantiques responsables respectivement du traitement taxonomique et thématique. Une soumission par rapport pré-enregistré (registered report) a été utilisée pour ce projet de recherche. Nos participants, adultes plus jeunes et plus âgés, étaient globalement appariés en termes de réserve cognitive, plus précisément en ce qui concerne le niveau d'éducation et comme le montrent les questionnaires évaluant l'engagement dans des activités cognitivement stimulantes, les tests MoCA et WAIS-III. Les résultats comportementaux ont confirmé que la tâche varie correctement la difficulté de la tâche puisque les taux d'erreur et les temps de réponse (RT) augmentent de manière linéaire avec l'augmentation des exigences de la tâche, à savoir dans la condition de forte demande. Nous avons constaté que la participation à des activités stimulantes sur le plan cognitif avait un impact positif à la fois sur les RT de référence et sur la précision. Nous n’avons pas observé de différence statistiquement significative dans la précision entre les participants jeunes et plus âgés, quelle que soit la condition. Nous avons constaté que des scores plus élevés aux tests WAIS-III et PPTT étaient positivement corrélés avec la précision chez les personnes âgées. En termes de RT, nous avons observé une différence statistiquement significative entre les participants jeunes et plus âgés pour la tâche et les conditions de référence, les adultes plus âgés étant plus lents à répondre en général. Les RT augmentent linéairement avec l'âge du participant. En tant que telle, la tâche de mémoire sémantique a réussi à a) manipuler la difficulté de la tâche sur deux niveaux d'exigences et b) démontrer une performance comportementale invariante selon l'âge pour le groupe plus âgé, comme l'exige le test du modèle CRUNCH (Fabiani, 2012 ; Schneider-Garces et al., 2010). Pour l'objectif n°1, les tests cruciaux du modèle CRUNCH, l'interaction IRMf groupe par difficulté, n'étaient pas cohérents avec les prédictions du modèle. Malgré nos résultats comportementaux, lorsque nous avons comparé directement la condition de faible demande avec la condition de forte demande, il n'y avait pas de différence statistiquement significative dans l'activation entre les conditions de faible et de forte demande. Nous n'avons pas non plus obtenu d'interaction entre tranche d'âge et difficulté. Nous avons obtenu des interactions significatives en comparant les conditions de demande faible et élevée avec la ligne de référence. Au niveau neuronal, indépendamment de l'âge, la tâche de jugement de similarité sémantique a activé un large réseau bilatéral fronto-temporo-pariétal. Pour l'objectif n°2 concernant l'effet de relation sémantique, le contraste de la condition taxonomique avec la condition thématique directement n'a pas trouvé d'activation robuste à un seuil corrigé. La condition taxonomique a donné des résultats intéressants par rapport à la condition de base. Sept groupes distincts dans le cortex fronto-temporo-pariétal ont été activés dans les deux hémisphères, y compris les lobes temporaux antérieurs (ATL) et la jonction temporo-pariétale gauche (TPJ). De plus, l'activation était significative dans le gyrus supérieur frontal gauche, le gyrus angulaire gauche (AG) et le gyrus frontal inférieur (partie orbitale) sur l'hémisphère droit. Cette découverte pourrait être en partie conforme à la théorie du double-hub, qui propose que les ATL bilatéralement et le TPJ agissent comme des hubs sémantiques. Bien que nous n'ayons pas trouvé d'activation significative dans les ATL pendant la condition taxonomique et dans le TPJ pendant la condition thématique, nous avons cependant constaté que dans la condition taxonomique parmi les sept clusters significativement activés, l'activation dans le gyrus frontal supérieur gauche était significativement corrélée avec la performance dans la condition taxonomique pour les deux groupes d'âge. L'activation dans le gyrus temporal moyen droit était également corrélée à l'amélioration des performances, mais cela n'était pas significatif dans le groupe plus âgé. En ce qui concerne la condition thématique, par contraste avec condition de référence, dix groupes distincts ont été activés, y compris la jonction temporo-pariétale (TPJ), alors que les ATL n'ont pas été activés de manière robuste pendant la condition thématique. Plus précisément, les régions activées comprenaient bilatéralement le gyrus angulaire, le gyrus temporal moyen, le gyrus frontal inférieur (partie triangulaire) et le gyrus frontal moyen. Nous visons à poursuivre des analyses supplémentaires pour explorer la relation entre les exigences de la tâche, le type de relation sémantique et la réorganisation neurofonctionnelle liée à l'âge. Cependant, ces résultats relatifs à la préservation avec l'âge des capacités à traiter les différentes relations sémantiques de mots sont associés à un certain nombre de réorganisations neurofonctionnelles. Celles-ci peuvent être spécifiques au traitement de différentes relations sémantiques et de différentes demandes de tâches. Il reste à déterminer si cette réorganisation est induite par les changements structurels du cerveau avec l'âge, ou par l'utilisation accrue de telles relations sémantiques tout au long de la trajectoire de la vie.Language overall is well preserved in aging (Meyer & Federmeier, 2010) whereas semantic memory may even improve (Kavé, Samuel-Enoch, & Adiv, 2009; Prinz, Bucher, & Marder, 2004; Salthouse, 2009; Verhaegen & Poncelet, 2013; Wingfield & Grossman, 2006), despite numerous neurophysiological changes taking place in the brain (Grady, Springer, Hongwanishkul, McIntosh, & Winocur, 2006; Kemper & Anagnopoulos, 1989; Wingfield & Grossman, 2006). The present study focuses on the preservation of semantic memory in aging, the ‘cognitive act of accessing stored knowledge about the world’ (Binder, Desai, Graves, & Conant, 2009) by means of a semantic judgment task manipulating semantic control with two demand levels (low and high) and two types of semantic relations (taxonomic-thematic). We used a novel task that varied task demands (low versus high) in 39 younger and 39 older adults. More specifically, the aims of this study was 1) to identify whether aging affects the brain activity subserving semantic memory in accordance with the CRUNCH predictions, through a semantic judgment task with two levels of demands (low and high). 2) To bridge the gap in the literature on the existence and evolution of semantic hubs in aging, in light of the dual and single-hub theories, by evaluating the effect of aging on the role of the Anterior Temporal Lobes (ATLs) and the Temporo-parietal junction (TPJ) as neural representations of the semantic hubs responsible for taxonomic and thematic processing, respectively. A submission by registered report was opted for this research project. Our participants, younger and older adults, were overall matched in regards to level of education and as shown in questionnaires assessing engagement in cognitively stimulating activities, MoCA and WAIS-III tests. The behavioral results confirmed that the task was successful in manipulating task difficulty, with error rates and RTs increasing with increasing task demands, namely in the high-demand condition. We found that engaging in cognitively stimulating activities impacted positively on both baseline RTs and accuracy and that higher scores on the WAIS-III and the PPTT tests were positively correlated with accuracy in older adults. There was no statistical difference in accuracy between younger and older participants regardless of the condition, so there was no age effect in accuracy. In terms of RTs, there was a statistically significant difference between younger and older participants for both the task and the baseline conditions, with older adults being slower to respond in general. RTs increased the more the participant’s age increased, which is in line with findings in the literature. As such, the semantic memory task was successful in a) manipulating task difficulty across two levels of demands and b) demonstrating age-invariant behavioural performance for the older group, as requires to test the CRUNCH model (Fabiani, 2012; Schneider-Garces et al., 2010). For objective no 1, the crucial test of CRUNCH model, the fMRI age group by task demand interaction was not found. We did not find statistically significant interaction neither between task demands and age group for RTs or accuracy, nor in regards to brain activation. At the neural level, independently of age, the semantic similarity judgment task activated a large network including bilateral inferior frontal, parietal, supplementary motor, temporal and occipital brain regions, which correspond overall with the semantic network, as suggested in the literature. Region of interest analyses demonstrated task demand effect in these regions, most notably in the left and right inferior frontal gyrus, the left posterior middle temporal gyrus, the posterior inferior temporal gyrus and the pre-frontal gyrus, regions which are typically associated with semantic control requirements. We did not find any significant interactions between task demands and activation in the regions of interest either. Several possible reasons may justify the lack of findings as predicted by the CRUNCH hypothesis. For objective no 2 in regards to the semantic relation effect, the contrast of the taxonomic with the thematic condition directly did not produce any robust activation at a corrected threshold. The taxonomic condition yielded interesting results when contrasted with the baseline one. Seven distinct clusters in the fronto-temporo-parietal cortex were activated across the two hemispheres, including the anterior temporal lobes (ATLs) and the left temporo-parietal junction (TPJ). Additionally, activation was significant in the left frontal syperior gyrus, the left angular gyrus (AG) and the inferior frontal gyrus (orbital part) on the right hemisphere. This finding could be partly in line with the dual-hub theory, that proposes that the ATLs bilaterally and the TPJ act as semantic hubs. Though we did not find the expected double dissociation e.g., significant activation in the ATLs during the taxonomic condition only and in the TPJ during the thematic condition only, we found however that in the taxonomic condition among the seven significantly activated clusters, activation in the left superior frontal gyrus was significantly correlated with performance in both age groups. Activation in the right middle temporal gyrus was also correlated with improved performance, but this was not significant in the older group. During the thematic condition, when contrasted with baseline, ten distinct clusters were activated, including the temporo-parietal junction (TPJ), whereas the ATLs were not robustly activated during the thematic condition. We aim to pursue additional analyses to explore the relation between task demands, type of semantic relation and age-related neurofunctional reorganization. However, these results in relation to the preservation with age of the abiliites to process the different semantic word relations is associated with a number of neurofunctional reorganizations. These can be specific to the processing of different semantic relations and different task demands. Whether this reorganization is induced by the structural changes in the brain with age, or by the enhanced use of such semantic relations along the trajectory of life is still under exploration

Timecourse of Cognitive and Brain Adaptation to Cognitive Training in At-risk Elderly

Maintaining cognitive ability in the elderly is a global priority. Computerised cognitive training (CCT) is among the few effective interventions but the boundaries and mechanisms underlying its effectiveness are largely unknown. Chapter 2 is the first systematic review and meta-analysis of 37 randomised controlled trials (RCTs) of CCT in healthy elderly, encompassing a total of 4,310 participants. CCT was effective on all the cognitive domains except for executive functions. Type of training program, mode of delivery, session length and training frequency were found to moderate CCT efficacy. The Timecourse Trial (Chapter 3) was a randomized, double-blind, active controlled longitudinal trial of CCT in 80 healthy elderly. Significant effects were found on global cognition, memory and processing speed, and dose-response curves differed across domains. These domain-specific gains also followed different decay curves after training cessation throughout the 12 months follow-up period. Chapter 4 investigates the neural underpinnings of gains in global cognition. Modification of resting-state functional connectivity was found to predict subsequent cognitive gains, gains that were also correlated to structural cortical plasticity. CCT is an effective intervention in the elderly. The field may do well to now focus on improving standards, large-scale trials and a further understanding of biological mechanisms

Measurement of allocentric processing in mild cognitive impairment and early Alzheimer’s disease using a virtual reality object location paradigm

Aim: Mild cognitive impairment (MCI) and Alzheimer’s Disease (AD) are major contributors to disability in old age and defined in the early stages by spatial memory deficits associated with hippocampal (HC) and entorhinal (EC) atrophy. Currently diagnosis occurs late in the process which limits efficacy of interventions. This study investigated the neural correlates of a novel object location task (OLT) in immersive virtual reality (iVR). Methods: Twenty amnestic MCI (aMCI) patients and twenty two healthy controls were tested on the iVR OLT, underwent neuropsychological testing and structural MRI scanning. OLT performance and HC, EC subfield volumetric data were compared between groups, and correlational analyses of HC/EC volumes and performance were conducted. Results: Participants with aMCI were significantly impaired in object location recall and object recognition compared to controls. They had significantly smaller total HC, subiculum, CA1, EC and perirhinal volumes. There was a significant interaction of group in analysis of neural correlates: OLT performance was strongly predicted by total HC and subiculum volumes in patients only. EC subfields were not significant predictors of performance. Conclusion: Performance on the novel OLT in immersive VR is a good indicator of HC integrity in older adults with amnestic MCI and can improve the diagnostic process for people with MCI and AD in the future

Falling Head Over Heels: Investigating the higher-level cognitive and electrophysiological processes underlying gait control and falls in older adults and stroke survivors

Falls are a common problem for Ireland’s older adults and stroke survivors, which have severe consequences for the individual and high care costs for the state. Current clinical interventions that focus solely on musculoskeletal function are not evidenced to be consistently effective in the long term, or in those older adults without muscle and bone impairments (Cadore, Rodríguez-Mañas, Sinclair, & Izquierdo, 2013; Teasell, McRae, Foley, & Bhardwaj, 2002). The role of cognition in gait control and falls has become increasingly apparent, with higher-level executive functions exhibiting a clear relationship with falls and cognitive decline with ageing (Morris, Lord, Bunce, Burn, & Rochester, 2016). This research aims to address a gap in the literature by identifying the specific higher-level executive processes that play a role in gait control, and examining if these processes are impaired in older adults and stroke survivors with a high risk of falling. Behavioural and electrophysiological measures were used to examine walking gait in both single- and dual-task conditions, as well as cognitive performances and the associated event-related potentials in healthy young and older adult “fallers” and “non-fallers”, and also in a sample of stroke survivors. The results suggest that executive top-down processes (working memory in particular), play a role in gait control during dual-task walking generally, and that executive processes are relied upon more in older age. This work suggests that there may also be neural markers of “successful” ageing that differentiate fallers from non-fallers, and that there can be substantial recovery of both cognition and gait post-stroke. These findings support the resource capacity and compensatory theories of neurocognitive ageing, and suggest that executive neuropsychological tasks could be developed to offer alternative cognitive/neural fall screening assessments and rehabilitation programmes for stroke patients and the wider older adult population

Falling Head Over Heels: Investigating the higher-level cognitive and electrophysiological processes underlying gait control and falls in older adults and stroke survivors

Falls are a common problem for Ireland’s older adults and stroke survivors, which have severe consequences for the individual and high care costs for the state. Current clinical interventions that focus solely on musculoskeletal function are not evidenced to be consistently effective in the long term, or in those older adults without muscle and bone impairments (Cadore, Rodríguez-Mañas, Sinclair, & Izquierdo, 2013; Teasell, McRae, Foley, & Bhardwaj, 2002). The role of cognition in gait control and falls has become increasingly apparent, with higher-level executive functions exhibiting a clear relationship with falls and cognitive decline with ageing (Morris, Lord, Bunce, Burn, & Rochester, 2016). This research aims to address a gap in the literature by identifying the specific higher-level executive processes that play a role in gait control, and examining if these processes are impaired in older adults and stroke survivors with a high risk of falling. Behavioural and electrophysiological measures were used to examine walking gait in both single- and dual-task conditions, as well as cognitive performances and the associated event-related potentials in healthy young and older adult “fallers” and “non-fallers”, and also in a sample of stroke survivors. The results suggest that executive top-down processes (working memory in particular), play a role in gait control during dual-task walking generally, and that executive processes are relied upon more in older age. This work suggests that there may also be neural markers of “successful” ageing that differentiate fallers from non-fallers, and that there can be substantial recovery of both cognition and gait post-stroke. These findings support the resource capacity and compensatory theories of neurocognitive ageing, and suggest that executive neuropsychological tasks could be developed to offer alternative cognitive/neural fall screening assessments and rehabilitation programmes for stroke patients and the wider older adult population

Influence of Age and Cognitive Reserve on Cognitive Function in HIV-infected South African Adults

Background. HIV remains a significant global public health concern. South Africa is one of the hardest-hit countries, housing more than 7 million people living with HIV (PLWH), a figure that represents more than 12% of the global infected population. Globally, HIV-associated cognitive impairment is present in almost 45% of PLWH, with 72% of that total burden found in Sub-Saharan Africa (Wang et al., 2020). The severity and trajectory of that impairment is, however, influenced by numerous risk and protective factors. This study aimed to investigate the strength of influence that two of these factors (cognitive reserve and age) have in a sample of HIV-positive South African adults. Method. Participants were 32 HIV-infected and virally suppressed adults (27 women; Mage = 41.13±9.34). They were administered the Cognitive Reserve Index Questionnaire (CRIq) and a comprehensive neuropsychological battery that assessed performance on tests of motor function, attention and working memory, information processing speed, language, memory, and executive function. They also provided 3T magnetic resonance imaging data. Bivariate correlations, independent-sample t-tests, and hierarchical regression models tested the prediction that age and cognitive reserve (as indexed by CRIq scores, fractional anisotropy, white and gray matter volume, education level, and IQ score), both independently and in interaction, will have significant effects on cognitive test performance (i.e., that increasing age and lower levels of cognitive reserve will be independently associated with poorer performance, and that older adults with lower levels of cognitive reserve will display the worst performance). Results. Regarding the association of age with global cognitive function (average performance across all tests), analyses detected a moderate negative correlation (r = -.425, p = .015.), a significant between-group difference (participants ≥ 45 years worse than those < 45 years, p = .012), and a significant proportion of variance accounted for (R 2 = .18, p = .016). There were no significant main effects of cognitive reserve, and no significant age x cognitive reserve interaction effect, on cognitive test performance. Conclusion. The current analyses confirmed the influence of age on cognition in PLWH but did not provide support for the same influence of cognitive reserve. Although neuroscience research attaches increasing importance to the construct of cognitive reserve, the lack of a universally-applied definition (and hence a standard measure) of the construct hampers investigations such as this and makes cross-study comparisons difficult. From a policy-making perspective, the contrasting findings regarding age and cognitive reserve is crucial because it is imperative that intervention efforts focus only on those modifiable factors that significantly impact cognitive function, especially in countries such as South Africa that are characterized by high HIV disease burden and limited clinical and infrastructural resources

Input and output order of recall as early markers of cognitive decline

This thesis explored the effects of age on free recall patterns in episodic memory. Neuropsychological and neuroimaging instruments were used to investigate the input (i.e., serial position effects) and output (i.e., temporal vs. spatial contiguity) of free recall in younger vs. healthy older individuals and in older adults with cognitive decline. In study 1 (Chapter 4), primacy (intended as the tendency to better remember items presented at the beginning of a list compared to the middle) at delayed recall was the most accurate serial position effect in predicting conversion to early stage Mild Cognitive Impairment (MCI), from a baseline of cognitively functioning older adults. In study 2 (Chapter 5), age differences in the use of spatial vs. temporal contiguity (intended as the tendency to retrieve items following the temporal, or spatial, context in which they have been learned) were explored in younger vs. healthy older adults. It was found that temporal contiguity was the most utilised associative process in both groups, although older adults showed lower temporal contiguity compared to younger adults. In study 3 (Chapter 6), the universality of temporal contiguity and the relationship between attentional processes and the output order of free recall were examined. Temporal vs. spatial contiguity were investigated during tasks meant to interfere with encoding processes, that is Divided Attention (DA) tasks and tasks involving presentation of verbal vs. pictorial material. Results showed consistent use of temporal contiguity in all experimental conditions, therefore suggesting the ubiquity of temporal contiguity and its involvement in retrieval processes. In study 4 (Chapter 7), the output order in free recall was investigated in younger and older adults in relation to prefrontal blood oxygenation, by means of functional Near-Infrared Spectroscopy (fNIRS). It was found that areas involved during temporal contiguity change with age, as younger adults showed greater activity of the right prefrontal cortex, whilst older adults engaged alternative or opposite regions. In study 5 (Chapter 8) the use of unrelated memory lists was investigated as a sensitive measure to detect age-related differences on the use of temporal vs. spatial contiguity. Moreover, age-associated differences in the use of temporal contiguity were explored at immediate vs. delayed recall. It was found that unrelated lists are able to detect age-related changes in the use of contiguity effects, and that temporal contiguity is negatively affected in both younger and older adults at delayed recall. In study 6 (Chapter 9) temporal clustering was investigated as potential predictor of conversion to Cognitive Unimpaired Declining (CUD) status, from a baseline of cognitively functioning older individuals. Results supported the hypothesis that temporal contiguity is a marker of cognitive decline, also when controlling for genetic information and for variables typically used in clinical practice. In summary, the findings of this thesis show that the input and output order of free recall, although quite stable, decline with age and that they may be added as a potential tool for early detection in clinical settings, and in the research field

Effects of Diversity and Neuropsychological Performance in an NFL Cohort

Objective: The aim of this study was to examine the effect of ethnicity on neuropsychological test performance by comparing scores of white and black former NFL athletes on each subtest of the WMS. Participants and Methods: Data was derived from a de-identified database in South Florida consisting of 63 former NFL white (n=28, 44.4%) and black (n=35, 55.6%) athletes (Mage= 50.38; SD= 11.57). Participants completed the following subtests of the WMS: Logical Memory I and II, Verbal Paired Associates I and II, and Visual Reproduction I and II. Results: A One-Way ANOVA yielded significant effect between ethnicity and performance on several subtests from the WMS-IV. Black athletes had significantly lower scores compared to white athletes on Logical Memory II: F(1,61) = 4.667, p= .035, Verbal Paired Associates I: F(1,61) = 4.536, p = .037, Verbal Paired Associates: II F(1,61) = 4.677, p = .034, and Visual Reproduction I: F(1,61) = 6.562, p = .013. Conclusions: Results suggest significant differences exist between white and black athletes on neuropsychological test performance, necessitating the need for proper normative samples for each ethnic group. It is possible the differences found can be explained by the psychometric properties of the assessment and possibility of a non-representative sample for minorities, or simply individual differences. Previous literature has found white individuals to outperform African-Americans on verbal and non-verbal cognitive tasks after controlling for socioeconomic and other demographic variables (Manly & Jacobs, 2002). This highlights the need for future investigators to identify cultural factors and evaluate how ethnicity specifically plays a role on neuropsychological test performance. Notably, differences between ethnic groups can have significant implications when evaluating a sample of former athletes for cognitive impairment, as these results suggest retired NFL minorities may be more impaired compared to retired NFL white athletes

Distinguishing Performance on Tests of Executive Functions Between Those with Depression and Anxiety

Objective: To see if there are differences in executive functions between those diagnosed with Major Depressive Disorder (MDD) and those with Generalized Anxiety Disorder (GAD).Participants and Methods: The data were chosen from a de-identified database at a neuropsychological clinic in South Florida. The sample used was adults diagnosed with MDD (n=75) and GAD (n=71) and who had taken the Halstead Category Test, Trail Making Test, Stroop Test, and the Wisconsin Card Sorting Test. Age (M=32.97, SD=11.75), gender (56.7% female), and race (52.7% White) did not differ between groups. IQ did not differ but education did (MDD=13.41 years, SD=2.45; GAD=15.11 years, SD=2.40), so it was ran as a covariate in the analyses. Six ANCOVAs were run separately with diagnosis being held as the fixed factor and executive function test scores held as dependent variables. Results: The MDD group only performed worse on the Category Test than the GAD group ([1,132]=4.022, p\u3c .05). Even though both WCST scores used were significantly different between the two groups, both analyses failed Levene’s test of Equality of Error Variances, so the data were not interpreted. Conclusions: Due to previous findings that those diagnosed with MDD perform worse on tests of executive function than normal controls (Veiel, 1997), this study wanted to compare executive function performance between those diagnosed with MDD and those with another common psychological disorder. The fact that these two groups only differed on the Category Test shows that there may not be much of a difference in executive function deficits between those with MDD and GAD. That being said, not being able to interpret the scores on the WCST test due to a lack of homogeneity of variance indicates that a larger sample size is needed to compare these two types of patients, as significant differences may be found. The results of this specific study, however, could mean that the Category Test could be used in assisting the diagnosis of a MDD patient