What Brain and Cognitive Markers Can Tell Us About ADHD Remission?

What you need to know

• The study identified several cognitive and brain markers that differ between individuals whose childhood ADHD persists versus remits in adolescence/young adulthood
• Markers of remission included measures of response speed, attention lapses, and brain activity related to attention and processing consistency
• These markers may reflect compensatory mechanisms in individuals whose ADHD symptoms improve over time
• Understanding markers of remission could help develop new interventions to promote improvement in those with persistent ADHD

Background on ADHD persistence and remission

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition that often continues from childhood into adolescence and adulthood. However, some individuals diagnosed with ADHD as children no longer meet diagnostic criteria when they are older - a phenomenon referred to as ADHD remission.

Understanding the cognitive and brain processes associated with ADHD remission versus persistence could provide valuable insights. Identifying markers of remission may reveal compensatory mechanisms that allow some individuals to overcome ADHD symptoms over time. This knowledge could potentially inform the development of new interventions to promote improvement in those with persistent ADHD.

Previous research has found that certain cognitive processes, like reaction time variability, differ between ADHD persisters, remitters, and controls. However, more fine-grained cognitive and neurophysiological markers of remission have not been thoroughly investigated. This study aimed to examine detailed measures of reaction time patterns and brain activity to identify potential markers of ADHD remission.

Study methods

The researchers followed up with 279 adolescents and young adults, including 110 who had been diagnosed with combined-type ADHD in childhood and 169 control participants without ADHD.

Of those with childhood ADHD:

• 87 continued to meet diagnostic criteria (ADHD persisters)
• 23 no longer met criteria (ADHD remitters)

Participants completed a computerized task that measured their reaction times under two conditions:

1. A slow, unrewarded baseline condition
2. A faster-paced condition with rewards for quick responses

The researchers analyzed participants’ reaction time patterns using an approach called ex-Gaussian analysis. This method breaks down reaction times into different components:

• Mu: the mean of the normal part of the reaction time distribution
• Sigma: the standard deviation of the normal part
• Tau: a measure of extremely slow responses

They also recorded participants’ brain activity using EEG and looked at:

• Theta power: brain oscillations linked to attention
• Theta phase consistency: how consistently the brain responds across trials
• Alpha and beta power: other types of brain oscillations

Key findings on cognitive markers

Several measures emerged as potential markers of ADHD remission:

Mu (mean reaction time)

• In the rewarded, fast-paced condition, remitters had significantly faster mean reaction times than persisters
• Remitters did not differ from controls
• This suggests remitters may be better able to optimize their performance in more engaging conditions

Tau (extremely slow responses)

• Remitters had significantly lower tau than persisters across both task conditions
• Remitters did not differ from controls
• This indicates remitters had fewer lapses in attention compared to persisters

Associations with functioning

• Higher tau was associated with greater functional impairment in daily life among those with childhood ADHD
• In the fast-paced condition, higher mu was also linked to more impairment

These cognitive measures appear to capture meaningful differences between those whose ADHD persists versus remits. The ability to respond more consistently and optimize performance in engaging conditions may reflect compensatory mechanisms in remitters.

Key findings on brain activity markers

The researchers also identified differences in brain activity patterns:

Theta power

• Remitters showed significantly higher theta power than persisters in centro-parietal brain regions
• Remitters did not differ from controls
• Higher theta power is associated with improved attention allocation

Theta phase consistency

• Remitters had significantly higher theta phase consistency compared to persisters
• Remitters did not differ from controls
• This indicates more consistent neural processing of stimuli in remitters

These brain activity markers suggest remitters may have improvements in attention-related neural processes compared to those with persistent ADHD. Like the cognitive markers, the brain measures did not differ between remitters and controls, potentially reflecting normalization of these processes.

Connections between cognitive and brain markers

The researchers found that the cognitive and brain markers of remission were significantly associated with each other. Specifically:

• Higher theta power was linked to faster mean reaction times (mu) and fewer extremely slow responses (tau)
• Higher theta phase consistency was also associated with lower mu and tau

This suggests the cognitive and neural markers may reflect overlapping processes involved in attention and performance optimization. Improvements in neural consistency and attention-related brain activity could allow remitters to respond more quickly and consistently.

Implications and future directions

This study provides new insights into the cognitive and brain processes that may be involved in ADHD remission from childhood to adolescence/young adulthood. The identified markers of remission could reflect compensatory mechanisms that develop over time in some individuals with ADHD.

Understanding these potential compensatory processes is valuable for several reasons:

1. It provides clues about how the brain may be able to overcome ADHD-related impairments in some cases.

2. The markers could potentially be used to track improvement in ADHD symptoms over time.

3. They may point to new targets for interventions aimed at promoting remission in those with persistent ADHD.

However, more research is still needed. Future studies should:

• Include larger groups of remitters to confirm these findings
• Follow participants over longer periods to examine how markers change with age
• Investigate whether interventions targeting these processes can improve outcomes

Additionally, it’s important to note that this study focused on a specific age range of adolescents and young adults. The applicability of the findings to older adults with ADHD remains to be determined.

Conclusions

• Several cognitive and brain markers appear to distinguish between persistent and remitted ADHD, including measures of response speed, attention lapses, and consistency of neural processing
• These markers may reflect compensatory mechanisms in individuals whose childhood ADHD remits by adolescence/young adulthood
• The findings provide new insights into processes potentially involved in overcoming ADHD symptoms over time
• Further research on these markers could inform the development of novel interventions to promote improvement in those with persistent ADHD