Introduction

Forgetting things is something that can happen to anyone, however, when this occurs frequently, and for some time this would be considered memory loss, known as amnesia. This can be a frustrating condition to live with, as it affects aspects of normal day-to-day life. According to the NHS, memory loss can be caused by the following:

• Ageing
• Anxiety or depression
• Stress
• Sleeping problems

Some of these causes can be treatable with medication or adjustments to lifestyle, which will reduce the frequency and severity of memory loss. In some cases, however, memory loss cannot be treated and could be a sign of a serious condition, like dementia.

Basics of dementia

What is dementia? 

Dementia is considered an umbrella term for symptoms associated with the decline in brain function, which includes memory loss. This condition affects behaviour, thinking and language. It is considered a progressive neurological condition, which means that as time goes on, the condition of the brain deteriorates, leading to worsened symptoms.¹ 

Common symptoms

A few of the common signs and symptoms of dementia include:²

• Difficulty in understanding time and place 
• Loss of interest in activities 
• Frequent misplacing of objects 
• Struggling to retain information 
• Changes in personality and behaviour 
• Difficulty in maintaining conversation  
• Difficulty in reading and writing 

There are different types of dementia, and so symptoms will vary. This means that someone with dementia may not show all these symptoms. It is difficult to identify dementia at an early stage due to some of these symptoms being common in most individuals, due to normal ageing.² 

Alzheimer’s Disease

One type of dementia is Alzheimer’s disease, which is the most common type as it makes up for up to 60-80% of dementia cases according to the Alzheimer’s Association. Risk factors of Alzheimer’s include:³ 

• Old age 
• Genetics  
• Head injury 
• Other existing health conditions 

The most defining and common symptom of this disease is memory loss, which deteriorates as the disease progresses. Memory loss begins to occur at an early stage of Alzheimer’s, however, this is difficult to detect as memory loss is not just specific to the disease, but could also be due to other factors, such as stress or lack of sleep.^2,3

How memory works

The brain contains the limbic system, which consists of structures such as the hippocampus and amygdala, which both are responsible for the storage and processing of memories. The hippocampus is responsible for retrieving memories and the amygdala is responsible for the linking of emotions to your memories. Within the brain, there are short and long-term memories. Short-term memories retain small, new information for a few seconds, and long-term memories are retained for much longer.^4,5

According to psychologist Endel Tulving, there are three different types of long-term memories:^6,7 

• Semantic memory - information regarding general knowledge and facts that requires conscious effort to recall, e.g. Paris being the capital of France
• Episodic memory - information regarding personal events and experiences that requires conscious effort to recall, e.g. your first day of school
• Procedural memory - information regarding carrying out learned tasks that do not require conscious effort to perform, e.g. tying shoe laces

The ability to recall and retrieve these short-term, and long-term memories, is affected in an individual suffering from dementia.² 

How dementia affects the brain

Brain changes in dementia

Dementia is caused by damage to the neurons and brain cells. The hippocampus and the amygdala, are the main parts of the brain affected by dementia. The brain's cortex shrinks as the disease progresses, causing a decrease in brain size. This unfortunately leads to damage of other structures of the brain, resulting in other symptoms seen in those suffering from dementia. Neurons of the brain are also affected as deposits of proteins cluster around these neurons affecting the signalling between the synapses.^1,3,4

Impact on memory 

Memory loss is caused by damage to structures of the brain, which are linked to memory processing, retrieval, and recall. Damage to the hippocampus means that the ability to recall information is severely affected, as this structure is responsible for the retrieval of memories, as well as the formation, and processing of new memories. The damage to the amygdala leads to the inability to recall emotions that were associated with a specific memory. As the disease progresses, the damage to these structures worsens, leading to an increase in memory loss over time.^3,4

Stages of memory loss in dementia

Early Stage

In the early stages of dementia, the cortex of the brain is still a normal size, however, there is damage to the hippocampus. This explains why memory loss is usually the first sign of dementia, especially in Alzheimer’s disease. Therefore, at this stage, an individual with Alzheimer’s may have difficulty retrieving newly formed memories, such as what they watched on TV last night, but can still recall their last day of school. The amygdala can also be affected at this stage, but this occurs later after damage to the hippocampus occurs.³ 

This means that an individual with the disease may still be able to recall emotions associated with the memory rather than the actual memory itself. It is complicated to diagnose an individual with Alzheimer’s at this stage because the difficulty in recalling these types of memories can happen to anyone due to ageing or other lifestyle factors, such as sleep, or alcohol consumption.^2,3 

Middle stage

At this stage, other symptoms are more obvious, making it easier to diagnose an individual with dementia. As the disease progresses, current problems with memory deteriorate even further. As well as difficulty in retrieving new information, an individual would have problems with recalling older information. An example of this would be the individual being unable to remember certain relatives or confusing other people they know as strangers.^2,3

Late stage 

In the last stage, most of the structures of the brain would have been damaged, the brain would have shrunk, and the neurons of the brain would also be damaged. In terms of memory loss, the individual would have lost the ability to recognise known people, objects, and places. This includes them being unable to identify themselves if looking in the mirror. An individual may still recall very early memories, and so, may only remember people they know from a specific early time point. For example, they may only remember their adult sibling as if they were a child, as this is the only way they remember them.³

Treatments and care

Unfortunately, there is no cure for dementia due to there being more than one type of dementia, which all vary from each other, with a variety of symptoms. However, certain treatments can help with these symptoms.³ Treatments involve:

• Medication to temporarily reduce symptoms, such as hallucinations and anxiety 
• Therapy, such as cognitive stimulation therapy, to improve memory and language 

The disease can be frustrating and challenging to live with for both, the individual with dementia, and for those close to them. Support is offered by the NHS, and other organisations, on how to cope with living with dementia, for both the family and the individual with the condition.

Summary

Dementia is a term used to describe symptoms associated with a decline in brain function. There are many types of dementia, however, memory loss is commonly associated with Alzheimer’s disease. In dementia, neurons and parts of the brain responsible for memory are damaged over time, leading to memory loss in the individual, which worsens as the disease progresses.