Adult-Onset ADHD: A Critical Analysis and Alternative Explanations.

Attention deficit/hyperactivity disorder (ADHD) is characterized as a neurodevelopmental disorder. However, data from several recent studies suggest that there may be adults who meet current criteria for ADHD, yet did not experience symptoms until adulthood (i.e., "adult-onset ADHD"). This systematic review evaluated and synthesized the empirical evidence on adult-onset ADHD to answer the question: Is the extant literature strong enough to evaluate adult-onset ADHD? Nine studies met strict inclusion/exclusion criteria. Results suggest that the methodologies of the extant studies were not strong enough to evaluate adult-onset ADHD. Insufficient methodologies provide presently unclear information about the nature of late-onset symptoms. These symptoms seem to exist but their source could be (1) adult-emergent symptoms that were previously surpassed due to lower environmental demands/supportive facilitators, (2) mimics that were not properly assessed, or (3) childhood-onset symptoms that were not detected earlier due to failure to come to clinical attention. Future directions, clinical recommendations, and limitations of the literature and the current review are discussed.

Live fast, die young? A review on the developmental trajectories of ADHD across the lifespan.

Attention-deficit/hyperactivity disorder (ADHD) is highly heritable and the most common neurodevelopmental disorder in childhood. In recent decades, it has been appreciated that in a substantial number of cases the disorder does not remit in puberty, but persists into adulthood. Both in childhood and adulthood, ADHD is characterised by substantial comorbidity including substance use, depression, anxiety, and accidents. However, course and symptoms of the disorder and the comorbidities may fluctuate and change over time, and even age of onset in childhood has recently been questioned. Available evidence to date is poor and largely inconsistent with regard to the predictors of persistence versus remittance. Likewise, the development of comorbid disorders cannot be foreseen early on, hampering preventive measures. These facts call for a lifespan perspective on ADHD from childhood to old age. In this selective review, we summarise current knowledge of the long-term course of ADHD, with an emphasis on clinical symptom and cognitive trajectories, treatment effects over the lifespan, and the development of comorbidities. Also, we summarise current knowledge and important unresolved issues on biological factors underlying different ADHD trajectories. We conclude that a severe lack of knowledge on lifespan aspects in ADHD still exists for nearly every aspect reviewed. We encourage large-scale research efforts to overcome those knowledge gaps through appropriately granular longitudinal studies.