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Brain Changes

How dementia affects the brain

A person with dementia can experience changes in personality, including sudden mood swings and emotional outbursts. The person may become upset over seemingly small things. To the person, however, these things may be significant. 

To understand more about the causes of mood changes, it’s helpful to learn more about how the brain works and how it can be affected by dementia. 

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Part of the brain is the cerebral cortex – a layer of cells covering the outside of the brain which is divided into four lobes:

  • Frontal lobes – located at the front of the brain, directly behind the forehead, they control thinking, memory, behaviour and movement. This part of the brain can become damaged in a person with dementia, meaning judgement and behaviour can be impaired. The frontal lobes also control motivation, meaning the person may lack interest in things they used to enjoy and seem apathetic.

  • The occipital lobes – located at the back of the head which control visual perception and motion. As a person’s dementia develops, they can struggle to recognise objects and people and may suffer from hallucinations.

  • The parietal lobes – located near the upper part of the skull near the back which control language and touch. Damage to these lobes caused by dementia can affect the person’s ability to speak and articulate themselves clearly.

  • The temporal lobes – they sit behind the ears and control hearing, general knowledge, learning and feelings. Damage to the temporal lobes can cause the person to struggle to understand language. Within the temporal lobes is an area called the hippocampus, which date stamps and logs memories. Damage to the hippocampus can make it a challenge to learn new things.

Another area of the brain affected by dementia includes the amygdala (located in the temporal lobes), which processes emotions and records reactions.

The brain needs an ongoing supply of oxygen and nutrients, which are in the blood, pumped to the brain by the vascular system. Damaged blood vessels caused by vascular dementia can mean cells don’t get enough blood and become starved of oxygen and nutrients, and die.

Different types of dementia can affect the brain in different ways. In the case of Alzheimer’s disease, the hippocampus is often the area damaged first, which explains why the person may find it harder to make new memories or learn something new. As the condition progresses, different parts of the brain are affected, including the lobes.

Vascular dementia occurs after a stroke or a series of mini-strokes, which means blood supply to a part of the brain is cut off, causing it to die. The part of the brain affected is damaged. The problems can be specific to the area where the damage has occurred.

Brain shrinkage usually occurs in the most common types of dementia.

When you understand how dementia affects brain health, it’s easier to appreciate and empathise with some of the challenges the person faces.


Sources:

https://www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/how-dementia-progresses/symptoms-brain

Alzheimer’s Society has a detailed downloadable guide to the brain and how it is affected by dementia:

https://www.alzheimers.org.uk/sites/default/files/2019-05/456lp-dementia-and-the-brain-190521.pdf