To avoid disappointment, frustration, and discouragement, don't expect their highest level of competence to be the standard. What's normal is that they will be inconsistent. Typically, they have problems with following through on instructions, paying attention appropriately to what they need to attend to, seem not to listen, be disorganized, have poor handwriting, miss details, have trouble starting tasks or with tasks that require planning or long-term effort, appear to be easily distracted, or forgetful. ADD is not a learning disability. Although ADD obviously effects the performance of a person in a school setting, it will also effect other domains of life, which can include relationships with others, running a home, keeping track of finances, and organizing, planning, and managing most areas of one's life.
ADD is a neurobiological disorder.
The most recent research shows that the symptoms of ADD are caused by a chemical imbalance in the brain. To understand how this disorder interferes with one's ability to focus, sustain attention, and with memory formation and retrieval, it is important to understand how the brain communicates information. This space is called a neural gap. With ADD there is a flaw in the way the brain manages the neurotransmitter production, storage or flow, causing imbalances. There is either not enough of them, or the levels are not regulated, swinging wildly from high to low.