The ability to think about multiple concepts at the same time is impaired in patients with attention deficit hyperactivity disorder (ADHD), and markedly worse in patients with comorbid bipolar disorder. New research suggests inflexible thinking in those with ADHD may be entirely due to the bipolar disorder. A study by a team of researchers at the Universidade Federal do Rio Grande do Sul looked at 278 ADHD patients. Those with signs of bipolar disorder scored far worse on the Wisconsin Car Sorting Test (WCST). It appears that people with ADHD have trouble with inhibitory control impairments. According to study author Claiton Bau, the addition of bipolar disorder adds set-shifting problems. Bipolar disorder is typified by extreme shifts in mood, activity levels and energy, with severe forms of the disorder marked by an inability to carry out daily tasks with any kind of effectiveness. Everyone has ups and downs, but a bipolar person will have trouble keeping a job, relationships and have a higher risk of suicide than people with other mental disorders. Scientists believe genetics, brain structure and functioning play the biggest roles in who will develop bipolar disorder. According to the Centers for Disease Control and Prevention, ADHD affects 6.4 million children ages 4-17. About 12 percent of boys are diagnosed with it at some point in their early lives, and girls at a rate of 4.7 percent. Some studies show that anywhere from one to six percent of adults suffer the effects of ADHD, and others show that around 80 percent of children with ADHD will carry it into adolescence. Dr. Bau said that the research suggests lesser psychosocial functioning could be the result of comorbid psychiatric disorders. With a better understanding of the relationship the comorbidity presents, doctors could improve their diagnosis and treatments and form more efficient interventions. Patients with bipolar disorder and ADHD scored an average of 86.1 on the WCST. Patients with ADHD by itself scored an average of 93.7 on the test. Test subjects with no mental health issues scored an average of 94.3. The comorbidities that were found to have little impact on patient scores include substance abuse disorders, anxiety, depression and panic disorder. The ADHD patients with bipolar disorder made 41.9 errors on their test compared to 34.3 errors made by patients with ADHD alone. Cognitive flexibility is important as it allows people the ability to understand a multitude of situations. Adapting to take in new knowledge and the transfer of skills and knowledge is part of having a cognitively flexible mind. When a person cannot combine their knowledge and experience in ways that allow them to adapt to a new situation, the outcome would be considered an example of cognitive inflexibility.