Attention deficit hyperactivity disorder (ADHD) is a neuropsychiatric syndrome which is hereditarily inherited, affected by environmental factors, and most commonly seen in childhood. It is a disorder that can continue in adulthood and is seen even in the geriatric population. ADHD, which may manifest itself with different symptoms in the geriatric population and the diagnosis of which is often overlooked, may sometimes present itself with dementia or depressive symptoms. Its prevalence is thought to be 3-4% in the elderly population. However, the diagnostic criteria of the ADHD in elderly population are not yet available and the diagnosis is made based on the criteria found in the DSM-5 (Diagnostic and Statistical Manual of Mental Health Disorders, 5th edition). Although some imaging and neurophysiological methods are utilized, there is no specific finding or image for ADHD. Defects in gray matter lesions in frontal and prefrontal areas can be demonstrated by magnetic resonance imaging (MRI). Some researchers think that functional MRI will provide more promising results in the future. Although the pathophysiology of ADHD has not yet been fully elucidated, clinical features are observed in a wide spectrum ranging from sleep disorders to dementia in the geriatric population. Therefore, ADHD should be examined in detail in the elderly population and new diagnostic criteria should be developed for the disorder by new studies. Because it is thought that the frequency of ADHD in the current literature is much less than that in real life.