Attention-deficit/hyperactivity disorder (ADHD) is a common disorder characterized by inattention or hyperactivity–impulsivity, or both. For a long time, ADHD was thought of as a disorder of children which would sometimes persist into adulthood. DSM 5 uses as a criterion that several symptoms have to be present prior to age 12 years.

To discuss the findings of 3 recent cohorts that show the onset of ADHD in adulthood.

A review of selected articles of interest using PubMed database.

3 large, longitudinal, population studies from Brazil, New Zealand (NZ) and the United Kingdom (UK) show that we are at a crossroads in our understanding of ADHD. In each study, the prevalence of adult-onset ADHD (Brazil, 10.3%; UK, 5.5%; and NZ, 2.7%) was much larger than the prevalence of childhood-onset adult ADHD (UK, 2.6%; Brazil, 1.5%; and NZ, 0.3%). They all propose different conclusions that would result in a paradigmatic shift in ADHD: in Brazil, that child and adult ADHD are “distinct syndromes”; in the UK, “that adult ADHD is more complex than a straightforward continuation of the childhood disorder” and in NZ, that adult ADHD is “not a neurodevelopmental disorder”. Faraone et al., in an editorial in JAMA Psychiatry, propose that these findings might correlate to subthreshold child ADHD before it emerges as adolescent- or adult-onset ADHD.

It's an exciting time in ADHD research. These new data work as an incentive to study adult-onset ADHD and how it emerges. Future research will shape our understanding of adult ADHD.

The authors have not supplied their declaration of competing interest.

Attention deficit hyperactivity disorder (ADHD) is a common disorder in childhood, which progresses to adulthood in about a fifth of cases. For various reasons, adult ADHD is a disorder not comprehensively assessed by psychiatrists, not least because the biological underpinnings are only recently being unmasked.

This selective review targets psychiatrists without a background in neuroscience and aims to describe the neurobiological basis of ADHD.

In total, 40 articles from a PubMed search were selected for inclusion based on sample population and methodology (neuroimaging studies). Studies focussing on adult participants were selected preferentially for inclusion. Seminal articles relevant to childhood populations were included for the purpose of understanding general concepts around ADHD.

The neuropathology of ADHD is not rooted in a single anatomical area, but in multiple parallel and intersecting pathways, which have demonstrated impaired functional connectivity in ADHD brains. Dysfunction in executive function, reward processing, attention networks and default networks play major roles in the neuropathology of this condition. Biological findings vary between individuals, with some showing greater dysfunction at cortical levels and others at subcortical levels, which is in keeping with its clinical heterogeneity.

Improved symptomatology in adulthood is linked to a number of factors. Maturation of the prefrontal cortex in early adulthood contributes to symptom attenuation in many cases, meaning that individuals with cortical dysfunction are more likely to grow out of symptoms, whereas individuals with subcortical dysfunction may be less likely to do so. There is emerging evidence for a similar but distinct disorder arising de novo in adulthood.

This work aims to review ADHD’s definition, epidemiology, frequent psychiatric comorbidities, differential diagnosis – highlighting it’s similarities with BPD –, treatment, and outcome.

A review of relevant literature was conducted alongside online database research (PubMed and Medscape).

ADHD is a neurodevelopmental disorder defined by persistent impairing levels of inattention, motor hyperactivity and impulsivity that exhibit a negative impact in functioning. It is estimated to affect 5% of children and 2.5% of adults. As the affected individual grows it is likely that the symptoms of hyperactivity will decrease, but the inattention, poor planning, and impulsivity tend to persist into adulthood, compromising social, academic, and occupational functioning.

It may be difficult to distinguish between ADHD and personality disorders, especially BPD. However, BPD has characteristic features like fear of abandonment, self-injury/suicidal behavior, extreme ambivalence, feelings of emptiness, and stress-related paranoia/severe dissociation, that are not present in ADHD.

Despite some similarities in clinical presentation in adolescents and young adults, PHDA and BPD differ substantially in their treatment, impairment in functioning, and outcome, making it crucial to establish a correct diagnosis which will enable proper treatment.

Micronutrients containing vitamins are reported to reduce symptom levels in persons with attention-deficit hyperactivity disorder (ADHD), but data on vitamin levels in ADHD are sparse.

To examine the relationship between vitamin concentrations, ADHD diagnosis and psychiatric symptoms in young adult ADHD patients and controls.

Eight vitamins and the nicotine metabolite cotinine were analysed in serum samples from 133 ADHD patients and 131 controls aged between 18 and 40, who also reported ADHD symptoms and comorbid conditions.

Lower concentrations of vitamins B2, B6 and B9 were associated with the ADHD diagnosis, and B2 and B6 also with symptom severity. Smokers had lower levels of vitamins B2 and B9.

ADHD patients were overrepresented in the group with low levels of some vitamins, possibly indicative of inadequate dietary intake of these micronutrients in a subgroup of patients. It is important to identify these patients in dietary intervention trials of ADHD.