ADHD is usually associated with being careless, impulsive and having difficulty concentrating. New research focused on ADHD in adults indicates a greater number of cognitive and motor symptoms, and that the effects of medication vary depending on the severity of symptoms. The results could pave the way for more personalised care and better day-to-day support.
ADHD is a neuropsychiatric deficit with an incidence of just under three per cent in adults (five to seven per cent in children). In the Swedish context, this equates to around 250,000 adults with ADHD.
"There is relatively little research into ADHD in adults compared with research into the condition in children. At the same time, an increasing number of people are being diagnosed with ADHD in adulthood, and there is a clear need for knowledge about how ADHD affects adults. This may shed light on the challenges of ADHD in adulthood - particularly when it comes to symptoms we don't usually associate with the condition," says Maurizio Cundari, a researcher at Lund University and a resident trainee in neuropsychology at the Neurology Clinic, Helsingborg Hospital, who led the study.
The researchers behind the study believe it is important to broaden perspectives on how ADHD should be diagnosed and treated. Partly because the effectiveness of medication is being questioned, and partly because ADHD is complex and needs to be understood more as a condition that affects several brain functions, not just attention
"ADHD cannot be diagnosed using biomarkers or specific behavioural indicators, but is categorised according to perceived severity - mild, moderate and severe. Healthcare and drug treatment are increasingly focused on precision medicine and personalised treatment. We need to clinically think along those lines when it comes to ADHD too," says Maurizio Cundari.
The researchers compared adults with ADHD (40 people) who were being treated with psychostimulants with adults with ADHD who were not receiving medication (52 people), as well as a control group without ADHD (80 people). The participants in the study underwent extensive assessments* of their cognitive and motor functions. Overall, no significant differences were observed between the medicated and unmedicated ADHD groups in the main analysis. However, clear differences emerged when the analyses were broken down by the severity of ADHD symptoms - mild, moderate or severe - with severe symptoms being associated with greater cognitive and motor deficits.
"Our findings suggest that it is not just the pharmacological treatment that distinguishes the groups from one another. Instead, differences in functioning appear to be primarily linked to the severity of symptoms and to underlying factors in the brain, such as executive functions, attention regulation, and motor and cognitive abilities. The motor aspects of ADHD include sensorimotor synchronisation and coordination, motor adaptation, motor speed, fine motor skills and precision, as well as oculomotor coordination," says Maurizio Cundari.
At the cognitive level, this includes visuospatial perception and visuospatial abilities, which is often forgotten in clinical practice, attention and processing speed, reaction time and visual scanning, as well as executive functions such as sequencing and working memory, cognitive flexibility (multitasking) and inhibitory control (impulse control).
Important for healthcare, research and everyday life
The researchers believe that the findings support a more personalised approach to healthcare, in which the severity of symptoms, based on measurable neurocognitive criteria, is taken into account when deciding upon a treatment.
The study also highlights the impact of ADHD and the choice of medication on working life and daily activities, where motor and cognitive challenges can play a decisive role.
"Overall, our study shows that adult ADHD is more complex than previously thought and that future care needs to be more personalised. There is now a need for more long-term studies that follow people with ADHD over time, as well as further research into different types and doses of medication, and into complementary interventions such as exercise, lifestyle changes and rehabilitation."
Motor and cognitive assessments
Motor skills
- sensorimotor synchronisation (motor movements that need to be adapted and temporally coordinated with an external rhythm or stimuli)
- sensorimotor coordination and adaptation (how sensory input and movement interact, and how the nervous system is constantly fine-tuning this interaction so that we can adapt to our surroundings)
- motor speed (the coordination between the nervous system and the muscles, and how quickly thoughts can be translated into physical activity)
fine motor skills and precision (difficulties coordinating small muscle movements, e.g. fastening buttons, tying shoelaces) - oculomotor coordination (the brain's ability to process visual information in order to control bodily movements)
Cognition
- visuospatial perception and visuospatial abilities
- attention and processing speed / reaction time / visual scanning
- executive functions: sequencing and working memory / cognitive flexibility (multitasking) / inhibitory control (impulse control)
