Sometimes only a few thousand brain cells become entirely free from the influence of current, or the current no longer functions within them in an effective way. The absence of current does not mean that current does not exist at all. It means that the current loses its order and discipline to such an extent that it becomes completely irregular.
Now the effect of a few thousand cells becoming irregular is that a person can no longer maintain the connection between one thought and another. At times this becomes deeply embarrassing for him. It is possible that not every individual experiences such incidents, yet many do. This in itself is not a disease, but when it happens repeatedly, it eventually becomes a condition that turns into illness.
This condition is known as severe weakness of memory.