This paper pulled together neurocognitive and brain imaging studies of how people with ADHD handle timing. It looked at children, teenagers and adults, so the picture covers all age groups rather than one. It was a narrative review, meaning the authors summarized the studies in words instead of combining them into one number.
The authors describe three areas of timing. One is motor timing, such as tapping in time with a beat. One is perceptual timing, such as judging how long something lasts. One is looking ahead in time, such as choosing between a small reward now and a larger reward later. Problems showed up most often in keeping time with a beat, telling durations apart, copying a duration, and preferring the sooner reward.
The results were fairly steady across studies. Nearly all of the motor timing studies found a difference between the ADHD and comparison groups, with one exception. Twelve studies of judging durations also found group differences.
The authors say these timing problems are linked to skills like working memory, attention and self control, but do not seem to be caused by them. Brain imaging pointed to timing networks that connect the front of the brain with deeper and rear regions. The stimulant methylphenidate was said to ease most of the timing problems. The findings were not fully consistent.
Source: Noreika V, Falter C, Rubia K. Timing deficits in attention-deficit/hyperactivity disorder (ADHD): Evidence from neurocognitive and neuroimaging studies. Neuropsychologia (2013). doi:10.1016/j.neuropsychologia.2012.09.036
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