HD is a brain disorder that affects all parts of brain function, and thus leads to physical, cognitive, and emotional symptoms. There is gradual loss of brain cells in certain parts of the brain, specifically the basal ganglia and the cerebral cortex. All the important domains of brain function such as cognitive abilities (thinking, judgement, and memory), physical abilities and emotion control get affected, although in a staggered and unpredictable manner during the course of the disease. These symptoms, typically, begin between the ages of 35 and 55 by which time most persons have already had children and so the disease continues to be transferred to the next generation. Besides this the symptoms can first occur in children (Juvenile HD, which is often more severe), or the elderly too.