A comprehensive investigation of memory impairment in attention deficit hyperactivity disorder and oppositional defiant disorder

Rhodes, Sinéad; Park, Joanne; Seth, Sarah; Coghill, David

doi:10.1111/j.1469-7610.2011.02436.x

Cited by 97 publications

(74 citation statements)

References 53 publications

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“…We selected groups excluding children with other psychiatric disorders and exposure to medication. Medication and co-morbidity have proven to affect both BIP and IB-EF in previous studies (Oosterlaan et al 1998(Oosterlaan et al , 2005Rhodes et al 2006Rhodes et al , 2012Coghill et al 2007;Chamberlain et al 2011;Swanson et al 2011;Wang et al 2013). Therefore, this sampling strategy provided a strong design for testing this specific hypothesis.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms underpinning inattention and hyperactivity: neurocognitive support for ADHD dimensionality

et al. 2014

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Background. Taxometric and behavioral genetic studies suggest that attention deficit hyperactivity disorder (ADHD) is best modeled as a dimension rather than a category. We extended these analyses by testing for the existence of putative ADHD-related deficits in basic information processing (BIP) and inhibitory-based executive function (IB-EF) in individuals in the subclinical and full clinical ranges. Consistent with the dimensional model, we predicted that ADHD-related deficits would be expressed across the full spectrum, with the degree of deficit linearly related to the severity of the clinical presentation.Method. A total of 1547 children (aged 6-12 years) participated in the study. The Development and Well-Being Assessment (DAWBA) was used to classify children into groups according to levels of inattention and hyperactivity independently: (1) asymptomatic, (2) subthreshold minimal, (3) subthreshold moderate and (4) clinical ADHD. Neurocognitive performance was evaluated using a two-choice reaction time task (2C-RT) and a conflict control task (CCT). BIP and IB-EF measures were derived using a diffusion model (DM) for decomposition of reaction time (RT) and error data.Results. Deficient BIP was found in subjects with minimal, moderate and full ADHD defined in terms of inattention (in both tasks) and hyperactivity/impulsivity dimensions (in the 2C-RT). The size of the deficit increased in a linear manner across increasingly severe presentations of ADHD. IB-EF was unrelated to ADHD.Conclusions. Deficits in BIP operate at subclinical and clinical levels of ADHD. The linear nature of this relationship provides support for a dimensional model of ADHD in which diagnostic thresholds are defined in terms of clinical and societal burden rather than representing discrete pathophysiological states.

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Section: Introductionmentioning

confidence: 99%

Mechanisms underpinning inattention and hyperactivity: neurocognitive support for ADHD dimensionality

et al. 2014

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“…Improvement in LTM is a critical target of therapeutic intervention in ADHD, as ample evidence shows a deficit in LTM in ADHD (Rhodes et al 2012). Psychostimulants are frequently prescribed to enhance classroom learning and are increasingly sought out by individuals without ADHD for the same reason.…”

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confidence: 99%

Animal model of methylphenidate's long-term memory-enhancing effects

et al. 2014

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Methylphenidate (MPH), introduced more than 60 years ago, accounts for two-thirds of current prescriptions for attention deficit hyperactivity disorder (ADHD). Although many studies have modeled MPH's effect on executive function, almost none have directly modeled its effect on long-term memory (LTM), even though improvement in LTM is a critical target of therapeutic intervention in ADHD. We examined the effects of a wide range of doses of MPH (0.01 -10 mg/kg, i.p.) on Pavlovian fear learning, a leading model of memory. MPH's effects were then compared to those of atomoxetine (0.1 -10 mg/kg, i.p.), bupropion (0.5 -20 mg/kg, i.p.), and citalopram (0.01 -10 mg/kg, i.p.). At low, clinically relevant doses, MPH enhanced fear memory; at high doses it impaired memory. MPH's memory-enhancing effects were not confounded by its effects on locomotion or anxiety. Further, MPH-induced memory enhancement seemed to require both dopamine and norepinephrine transporter inhibition. Finally, the addictive potential of MPH (1 mg/kg and 10 mg/kg) was compared to those of two other psychostimulants, amphetamine (0.005 mg/kg and 1.5 mg/kg) and cocaine (0.15 mg/kg and 15 mg/ kg), using a conditioned place preference and behavioral sensitization paradigm. We found that memory-enhancing effects of psychostimulants observed at low doses are readily dissociable from their reinforcing and locomotor activating effects at high doses. Together, our data suggest that fear conditioning will be an especially fruitful platform for modeling the effects of psychostimulants on LTM in drug development.

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“…WM dysfunctions are also common in neurological disorders and mental retardation, and are among the most prominent cognitive deficits in psychiatric disorders, such as attention-deficit/ hyperactivity disorder (ADHD; Willcutt et al 2005;Rhodes et al 2012) or schizophrenia (Lett et al 2013). WM functions also undergo considerable changes throughout the lifespan, and particularly during development (Best and Miller 2010;Sander et al 2012), where prominent changes beyond childhood reflect late maturation in adolescence (Dumontheil et al 2011;van Ewijk et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Frontal Midline Theta Reflects Individual Task Performance in a Working Memory Task

et al. 2014

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Frontal midline (fm-)theta activity has been related to working memory (WM) processes, as it typically increases with WM load. The robustness of this effect, however, varies across studies and subjects, putting limits to its interpretation. We hypothesized that variation in the fm-theta effect may reflect individual differences in task difficulty with increasing WM load as indicated by behavioural responses. We further tested whether effects in the alpha range are robust markers of WM load. We recorded 64-channel EEG from 24 healthy adults while they memorized either 2 or 4 unfamiliar symbols (low vs. high WM load) in a modified Sternberg task. The last 2 s of the retention phase were analyzed for WM load-related changes in the theta (5-7 Hz) and alpha range (lower: 8-10 Hz, upper: 10.5-12.5 Hz). Higher WM load led to less accurate and slower responses. The increase of fm-theta with WM load was most pronounced at fm electrodes, localized to anterior cingulate regions, and correlated with the participants' decrease in accuracy due to higher WM load. Alpha peak frequency increased in the high compared to the low WM load condition, corresponding to a decrease in lower alpha range across all channels. The results demonstrate that previously reported variation in fm-theta workload effects can partly be explained by variation in task difficulty indexed by individual task accuracy. Moreover, the results also demonstrate that alpha WM load effects are prominent when separating upper and lower alpha. AbstractFrontal midline (fm-)theta activity has been related to working memory (WM) processes, as it typically increases with WM load. The robustness of this effect, however, varies across studies and subjects, putting limits to its interpretation. We hypothesized that variation in the fm-theta effect may reflect individual differences in task difficulty with increasing WM load as indicated by behavioural responses. We further tested whether effects in the alpha range are more robust markers of WM load. We recorded 64-channel EEG from 24 healthy adults while they memorized either 2 or 4 unfamiliar symbols (low versus high WM load) in a modified Sternberg task. The last 2 seconds of the retention phase were analyzed for WM load-related changes in the theta (5-7 Hz) and alpha range (lower: 8-10 Hz, upper: 10.5-12.5 Hz). Higher WM load led to less accurate and slower responses. The increase of fm-theta with WM load was most pronounced at frontal midline electrodes, localized to anterior cingulate regions, and correlated with the participants' decrease in accuracy due to higher WM load. Alpha peak frequency increased in the high compared to the low WM load condition, corresponding to a decrease in lower alpha range across all channels. The results demonstrate that previously reported variation in fm-theta workload effects can partly be explained by variation in task difficulty indexed by task accuracy. Moreover, the results also demonstrate that alpha WM load effects are prominent when separating upper and lower alpha.

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A comprehensive investigation of memory impairment in attention deficit hyperactivity disorder and oppositional defiant disorder

Cited by 97 publications

References 53 publications

Mechanisms underpinning inattention and hyperactivity: neurocognitive support for ADHD dimensionality

Mechanisms underpinning inattention and hyperactivity: neurocognitive support for ADHD dimensionality

Animal model of methylphenidate's long-term memory-enhancing effects

Frontal Midline Theta Reflects Individual Task Performance in a Working Memory Task

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