Longitudinal Neuropsychological Assessment in Two Elderly Adults With Attention-Deficit/Hyperactivity Disorder: Case Report

Cognitive and Neuroimaging Profiles of Older Adults With Attention Deficit/Hyperactivity Disorder Presenting to a Memory Clinic

OBJECTIVE

Some features of attention-deficit/hyperactivity disorder (ADHD) may resemble those of mild cognitive impairment (MCI) in older adults, contributing to diagnostic uncertainty in individuals seeking assessment in memory clinics. We systematically compared cognition and brain structure in ADHD and MCI to clarify the extent of overlap and identify potential features unique to each.

METHOD

Older adults from a Cognitive Neurology clinic (40 ADHD, 29 MCI, 37 controls) underwent neuropsychological assessment. A subsample (n = 80) underwent structural neuroimaging.

RESULTS

Memory was impaired in both patient groups, but reflected a storage deficit in MCI (supported by relatively smaller hippocampi) and an encoding deficit in ADHD (supported by frontal lobe thinning). Both groups displayed normal executive functioning. Semantic retrieval was uniquely impaired in MCI.

CONCLUSION

Although ADHD has been proposed as a dementia risk factor or prodrome, we propose it is rather a pathophysiologically-unique phenotypic mimic acting via overlap in memory and executive performance.

Association Between Mild Neurocognitive Disorder Due to Alzheimer's Disease and Possible Attention-deficit/Hyperactivity Disorder: A Case Report

Recent literature concerning attention-deficit/hyperactivity disorder (ADHD) underlines the persistence of this neurodevelopmental illness in older patients. Comorbidity with a neurodegenerative disease is thus possible. However, few studies have investigated this topic. To our knowledge, this is the first case report of such a possible association, which raises important questions about clinical presentation, symptoms, diagnosis, and treatment. A 72-year-old man, without any psychiatric history, presented with depression, subjective memory loss, and attention deficit and anxious symptoms, and was diagnosed with mild neurocognitive disorder due to Alzheimer's disease. However, the patient's attentional symptoms appeared to have been present since childhood. A formalized diagnostic interview assessing for ADHD did not allow for a clear diagnosis, possibly due to recall bias. The patient's anxiety symptoms also did not respond well to cognitive behavioral therapy coupled with different antidepressants. We hypothesized the presence of ADHD, with the symptoms balanced until now by the patient's high cognitive capacities, and we postulated that the onset of a neurogenerative process may have disrupted this balance. In this case report, we discuss symptom dimensionality, the interplay between neurodegenerative and neurodevelopmental diseases, and various treatment options. Attentional deficits and anxiety symptoms are frequent in mild neurocognitive disorders due to neurodegenerative illnesses. It is important to explore the time of onset of such symptoms since neurodegenerative processes can worsen neurodevelopmental conditions. Moreover, identification of a pre-existing neurodevelopmental condition can lead to alternative care and treatment options. In addition, the unexplained worsening of ADHD symptoms should prompt clinicians to assess for a neurodegenerative process.

Longitudinal Cognitive Performance of Older Adults With ADHD Presenting to a Cognitive Neurology Clinic: A Case Series of Change Up to 21 Years

Background: The neuropsychological features of older adults with ADHD are largely unknown. This retrospective chart review aims to elucidate their cognitive trajectories using a case series of six older adults with ADHD presenting with memory complaints to a cognitive neurology clinic, whom we argue are a particularly relevant group to study due to their potential to mimic neurodegenerative syndromes.

Methods: Participants were included if they were age 40 or older at intake, had ADHD based on DSM-5 criteria, and had cognitive data collected prior to 2014 with follow-up at least 5 years later.

Results: Five men and one woman were included (M = 53.8 years at intake) and had an average of 135.0 months of follow-up data available. Despite notable between- and within-subject variability, cognition generally improved or remained stable across visits. Two participants experienced notable memory decline, but a global consideration of their performance in other domains suggests these deficits may be frontally-mediated.

Conclusion: In this small sample, cognition remained generally unchanged across 5–21 years. Isolated impairments likely reflect substantial intra-individual variability across time and measures.