The term "brain disease" refers to any condition or disorder that affects the brain and its normal functioning. This can include a wide range of conditions, such as neurodegenerative diseases like Alzheimer's or Parkinson's, mental health disorders like depression or anxiety, traumatic brain injuries, infections like meningitis, and other neurological or psychiatric illnesses. The phrase "brain disease" is often used to describe these conditions collectively because they all involve some form of damage or dysfunction to the brain tissue itself or the neural connections within it. While many brain diseases have physical causes, such as genetic mutations, injuries, or infections, others may be influenced by environmental factors, lifestyle choices, or a combination of both. Regardless of the cause, these conditions can have significant impacts on an individual's cognitive abilities, emotional well-being, and overall quality of life.