# Explain why studying the brain is extremely difficult for scientists trying to understand and cure diseases such as Alzheimer's and Parkinson's disease.

> WJEC A-Level Biology (Wales) — 4.2 Inheritance · Explain · 5 marks

> Research into the structure and functions of the brain could have a huge impact on our ability to cure diseases such as Alzheimer's and Parkinson's disease. In many of these diseases, nerve cells in the cerebral cortex begin to die, leading to a decrease in functionality.

## Mark scheme (5 marks)

1. The brain contains billions of neurones, making it extremely complex to study
2. The brain must still be working / the patient must be alive for many functions to be studied
3. There are ethical issues because patients with brain damage may not be able to give informed consent
4. Studies are only carried out after damage has occurred so it cannot be compared to the healthy brain / a baseline is absent
5. Brain damage rarely causes a single problem, making it difficult to match specific problems to specific damaged neurones / areas

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](https://www.gradenine.co.uk/learn)
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