It is normal to occasionally forget assignments, colleague's names or an associate's telephone number, and then to remember them later. Individuals with a dementia such as Alzheimer's Disease may forget things more often and not remember them later. They may repeatedly ask the same question, not remembering the answer, or even that they have already asked the question.
Busy people be can distracted from time to time, leaving carrots on the stove and only remembering to serve them at the end of the meal. People with Alzheimer's disease, on the other hand, can prepare a meal and forget to serve it. They can even forget that they made it.
Everyone has trouble finding the right word sometimes, but they can finish their sentence by substituting another appropriate word. A person with Alzheimer's disease may forget simple words or substitute inappropriate words, making their sentence incomprehensible.
It is normal to forget, for a moment, what day of the week it happens to be, or a destination. People with Alzheimer's disease, however, can become lost on their own street or in a familiar shopping mall, not knowing where they are, how they got there, or how to get home.
People can become so immersed in an activity or telephone conversation that they temporarily forget about the child that they are watching. On the other hand, a person with Alzheimer's disease could entirely forget the child under their care and leave the house to visit a neighbor.