Adult attention deficit hyperactivity disorder is the neurological condition of attention deficit hyperactivity disorder (ADHD) in adults. About one-third to two-thirds of children with symptoms from early childhood continue to demonstrate ADHD symptoms throughout life. : 44 Three types of ADHD are identified in the DSM-5 as:

Predominantly Inattentive Type (ADHD-PI or ADHD-I)
Predominantly Hyperactive or Hyperactive-Impulsive Type (ADHD-PH or ADHD-HI)
Combined Type (ADHD-C)In later life, the hyperactive/impulsive subtype manifests less frequently. : 44  The hyperactivity symptoms tend to turn more into "inner restlessness", starting in adolescence and carrying on in adulthood.Adult ADHD is typically marked by inattention and hyperfocus, hyperactivity (often internalised as restlessness), emotional dysregulation, and excessive mind wandering. Specifically, adults with ADHD present with persistent difficulties in following directions, remembering information, concentrating, organizing tasks, completing work within specified time frames and appearing timely in appointments. These difficulties affect several different areas of an ADHD adults life, causing emotional, social, vocational, marital, legal, financial and/or academic problems.Diagnosis follows one or several psychiatric assessment which may include examination of personal history, observational evidence from family members or friends, academic reports, often going back to school years, as well as evaluation to diagnose additional possible conditions which often coexist with ADHD, called comorbidities or comorbid disorders. The condition often runs in families, and while its exact causes are not fully known, genetic or environmental factors are understood to play a part. ADHD often - but not always - is a childhood-onset condition.
These can include ADHD symptom checklists, standardized behavior rating scales, a detailed history of past and current functions including the persons history of childhood behavior and school experiences, and information obtained from family members, friends, or significant others. The evaluations also seek to rule out other conditions or differential diagnoses such as depression, anxiety, or substance use disorders. Other diseases such as hyperthyroidism may exhibit symptoms similar to those of ADHD, and it is imperative to rule these out as well. Autism is sometimes mistaken for ADHD, due to impairments in executive functioning found in some people with autism. However, autism also typically involves difficulties in social interaction, restricted and repetitive patterns of behavior and interests, and problems with sensory processing, including hypersensitivity. Along with this, the quality of diagnosing an adult with ADHD can often be skewed being that the majority of adults with ADHD also have other complications, ranging from anxiety and depression to substance abuse.Formal tests and assessment instruments such as IQ tests, standardized achievement tests, or neuropsychological tests typically are not helpful for identifying people with ADHD. Furthermore, no currently available physiological or medical measure is definitive diagnostically. However, psycho-educational, such as the Continuous Performance Test (CPT), and medical tests are helpful in ruling in or out other conditions (e.g. learning disabilities, allergies) that may be associated with ADHD-like behaviors.The use of neuroimaging is also steadily increasing to help in an ADHD diagnosis.