A Systematic Review and Comparison of Neurocognitive Features of Late-Life Attention-Deficit/Hyperactivity Disorder and Dementia With Lewy Bodies

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) in adulthood and dementia with Lewy bodies (DLB) share many cognitive and noncognitive similarities. The overlapping features between both disorders complicate differential diagnosis. The aim of the current systematic review was to compare patterns of neuropsychological profiles in older adults with ADHD and DLB.

METHOD

Of the 1989 ADHD-related articles and 1332 DLB-related articles screened, 3 ADHD and 25 DLB articles were retained for qualitative synthesis and review.

RESULTS

A synthesis of individual study findings revealed isolated working memory deficits for late-life ADHD, and performance deficits in areas of attention, memory, language, and visuoperceptual abilities for DLB. Results were limited by small samples and absence of data in some cognitive domains.

CONCLUSION

These initial findings support potentially unique neurocognitive profiles for ADHD in later life and DLB that would enable practitioners to differentially diagnose and appropriately treat older adults presenting with these phenotypically similar disorders.

Biomarker support for ADHD diagnosis based on Event Related Potentials and scores from an attention test

ADHD is a heterogeneous neurodevelopmental disorder associated with dysfunctions in several brain systems. Objective markers of brain dysfunction for clinical assessment are lacking. Many studies applying electroencephalography (EEG) and neuropsychological tests find significant differences between ADHD and controls, but the effect sizes (ES) are often too small for diagnostic purposes. This study aimed to compute a diagnostic index for ADHD by combining behavioral test scores from a cued visual go/no-go task and Event Related Potentials (ERPs). Sixty-one children (age 9-12 years) diagnosed with ADHD and 69 age- and gender-matched typically developing children (TDC) underwent EEG-recording while tested on a go/no-go task. Based on comparisons of ERP group-means and task-performance, variables that differed significantly between the groups with at least moderate ES were converted to a five points percentile scale and multiplied by the ES of the variable. The sum-scores of the variables constituted the diagnostic index. The index discriminated significantly between patients and TDC with a large ES. This index was applied to an independent sample (20 ADHD, 21 TDC), distinguishing the groups with an even larger ES. The diagnostic index described has the potential to support assessment. Further research establishing diagnostic indexes for differential diagnoses is needed.

Transcranial direct current stimulation in attention-deficit/hyperactivity disorder: A meta-analysis of clinical efficacy outcomes

BACKGROUND

Evidence for the application of transcranial direct current stimulation (tDCS) in the clinical care of attention-deficit/hyperactivity disorder (ADHD) is limited. Therefore, we aimed to summarize study results using meta-analyses of measures of the cardinal symptoms of ADHD.

METHODS

We conducted a systematic literature search (PubMed/pubpsych/PsychInfo/WOS) until 01/05/2020 for randomized controlled trials (RCTs) evaluating tDCS vs. control condition in patients with ADHD. A random effects meta-analysis of symptom-related outcomes was performed separately for data on the immediate effect and follow-up. Subgroup- and metaregression analyses for patient characteristics and tDCS parameters were included.

RESULTS

Meta-analyzing 13 studies (n=308, age=23.7±13.3), including 20 study arms, tDCS had an immediate effect on overall symptom severity, inattention, and impulsivity, but not on hyperactivity. Results were significant in children and adolescents (8 studies, n=133, age=12.4±3.0). Follow-up data (3 days-4 weeks after stimulation) suggested an ongoing beneficial effect regarding overall symptom severity and a delayed effect on hyperactivity.

DISCUSSION

TDCS seems to be a promising method to treat clinical symptoms in ADHD with long-lasting effects. Still, more research considering the individual neuropsychological and anatomical dispositions of the subjects is needed to optimize tDCS protocols and efficacy. Safety issues of tDCS treatment in children and adolescents are addressed.