Overview

Dementia is an overall term describing a group of symptoms affecting the individual. The person affected has loss of memory, difficulty in thinking and reasoning and also affects their day-to-day activities. Dementia is caused by damage to the nerve cells in the brain.¹

Mixed dementia is a condition where there is a combination of two or more types of dementia at the same time. A person affected with mixed dementia has signs and symptoms of both disease conditions. The most common type of mixed dementia is Alzheimer’s disease and vascular dementia. In the case of mixed dementia it is difficult to diagnose which type of dementia has more of an effect.

In the case of a person with mixed dementia, the mental health of the person declines faster than in other types of dementia. When mental health is affected it interferes with daily activities.

Causes of dementia

Dementia is caused by various diseases which cause damage to the nerve cells of the brain. This then affects the brain’s ability to communicate and function properly.^1,2

Types of Dementia

Dementia is divided into the following : 

Primary dementia 

In this group, the main symptoms are related to dementia and they are:

• Alzheimer’s disease: Alzheimer's is the most common cause of dementia. Abnormal build-up of proteins like amyloid protein and tau protein in the brain causes blocks between the nerve cells and damages them.³
• Vascular dementia: This is caused by a decrease in blood flow which damages the brain tissue. This is caused by a stroke or atherosclerosis which damages or blocks the blood vessels in the brain. This causes loss of memory, confusion, difficulty in concentration and coordination.^4,5 
• Lewy body dementia: In this condition, the protein builds up like clumps in the brain cells. Damage caused to the nerve cells causes difficulty in movement and sleep, as well as causing memory loss and visual hallucination⁶
• Frontotemporal dementia (FTD): Abnormal buildup of protein in the frontal and temporal lobes of the brain causes damage to the area. This causes changes in the person’s behaviour, personality, judgement and language
• Mixed dementia: The changes in the brain caused by various causes, a person with mixed dementia has a combination of more than one type of dementia like Alzheimer’s, vascular and Lewy body dementia

Secondary dementia

In this type, dementia is caused by other disease conditions and they are: 

• Huntington’s disease: A genetic condition which is inherited, that causes the brain cells to function slowly and later degenerate. The condition affects the memory and causes uncontrollable movements⁷
• Traumatic brain injury (TBI): It is a serious medical condition which can cause disability or even death. Repeated blows to the head or hard bumps can cause brain injury
• Creutzfeldt-Jakob disease: It is a rare and severe brain condition where an abnormal protein called prions causes the disease. The condition of the person worsens very quickly and it affects their memory, behaviour, communication and judgement⁸
• Wernicke-Korsakoff syndrome: It is a severe brain disease caused by the deficiency of vitamin B1 (thiamine). This condition is most commonly seen in people with an alcohol use disorder and people experiencing malnutrition⁹ 
• Parkinson’s disease: It is a condition caused by the degeneration of the brain and causes tremors, difficulty in balancing and movement whilst also affecting muscle control

Reversible dementia

In this type, dementia-like symptoms occur which are caused by other causes and illnesses.

• Normal pressure hydrocephalus (NPH): This condition occurs when the cerebrospinal fluid (CSF) accumulates in the ventricles of the brain. This can be caused by infection, from previous brain surgery or a brain bleed. This condition causes forgetfulness, poor balancing, change in behaviour and mood swings^10,11
• Infections and immune disorders: Symptoms like dementia can be caused by infections (HIV, syphilis, Lyme disease)¹²
• Medicinal side effects: Some medicines have dementia-like side effects. These include antidepressant drugs, anti-anxiety drugs and anti-seizure medicines
• Metabolic or endocrine conditions: A person affected with thyroid disease or a decreased blood sugar level can have certain dementia-like symptoms
• Brain tumour: Brain tumours can be benign or malignant and can affect the normal functioning of the brain

Symptoms

• The most common symptom is memory loss¹³
• Forgetfulness of recent events
• Disorientation and confusion about the present (which makes decision-making difficult)
• Difficulty in communicating
• Difficulty in organising
• Trouble performing multiple or complex tasks
• Difficulty in control of movements and coordination which makes daily activities more difficult
• Depression¹⁴
• Change in behaviour and mood
• Anxiety¹⁵
• Hallucination

Risk factors

A person with a lower risk factor is less likely to get dementia but it does not mean they won’t get dementia. 

Age

Ageing is the most commonly known risk factor for dementia. An increase in age is not a cause for dementia but it increases the risk. People aged over 65 are at more risk of having dementia. After the age of 65 roughly doubling every five years increases their risk. 

As the person ages they become more fragile and most of them are more likely to have the following: 

• Difficulty in thinking
• Difficulty in remembering certain things
• Have high blood pressure or other medical conditions
• Damages to the brain cells and blood vessels
• Increased risk of having a stroke
• Decreased immunity
• Slower recovery from injuries

Although older people are at high risk of getting dementia, younger people below the age of 65 can also get dementia.

Family history

Certain genes are passed down from a parent to their children which are known as inherited genes. The risk increases when one or more family members have dementia.¹⁶ 

Medical conditions

Certain long-term medical conditions and the medications taken may reduce the damage to the brain. Some of the conditions are: 

• Diabetes: Glucose is an important source of energy for the brain and for the cells to make muscles and tissues. Increased level of sugar in the blood leads to diabetes and it is a serious health condition
• Heart problems: Increased cholesterol, obesity, high blood pressure and atherosclerosis (fat deposit in the artery wall) can increase the risk of dementia. Damage to the blood vessels can lead to stroke and a reduced blood flow, which can damage the brain and cause dementia
• Loss of hearing: Age-related hearing loss is a common condition. Difficulty in hearing indicates damage in the area of the brain that helps us hear. This makes the person increase their effort to understand the sounds and this may lead to changes in the brain and affect their memory

People with loss of hearing are more likely to withdraw from society and this leads to isolation and depression. 

• Loss of vision: Severe loss of vision causes a high risk of dementia especially when it is not treated. People with loss of vision tend to avoid social interactions,  becoming more isolated and they tend to have depression. Treating or correcting vision helps in reducing dementia
• Head injury: Head injury caused by an accident, fall, or during sports can affect the brain and can increase the risk of dementia. Head injuries are classified into mild, moderate and severe according to the person's response after the injury
• Air pollution: In the case of air pollution, it contains small particles from traffic fumes, burning wood or plastic. These particles can affect the nervous system and increase its degeneration. Long exposure to air pollution can affect the lungs and heart. This increases the risk for dementia
• Loss of sleep
• Depression: It is a mental condition which might indicate the risk of dementia
• Down syndrome: It is a genetic condition where the person has loss of sleep, heart disease, hearing or vision complaints. They might develop an early onset of Alzheimer’s disease

Lifestyle

Our lifestyle choices can affect our health conditions and some of them are: 

• Physical activity: Regular exercise helps in reducing the risk of dementia
• Alcohol: Alcohol consumption for a long period of time can affect the brain and can increase the risk of early onset of dementia
• Smoking: Smoking regularly increases cardiovascular issues. The harmful contents like nicotine can damage the blood vessels and it may cause a reduced blood supply to the brain
• Social activity: Social interactions help a person to improve their mood and relieve stress. Social activities like participating in group activities, volunteering, and learning help to improve memory and thought processes. Healthy behaviour helps in reducing the risk of dementia

FAQs

What is the behaviour of a person affected with dementia?

A person affected by dementia becomes over-sensitive to their surroundings, they also become easily frustrated and angry.

What are the symptoms of dementia?

People with dementia have memory loss, confusion, difficulty in thinking and expressing themselves which affects their daily activities.

What are the late-stage symptoms of dementia?

• Difficulty in doing daily activities
• Limited interaction with others
• Loss of appetite
• Confusion
• Bladder and bowel incontinence

How can dementia get worse?

• Lack of sleep
• Unhealthy food habits
• Increased alcohol consumption
• Smoking
• Reduced physical activity
• No social activity

Summary

Dementia is a term for a group of diseases that affects memory, thinking, mood, personality and behaviour. Dementia occurs when certain parts of the brain are affected by infections or diseases. When mental health is affected it interferes with daily activities. Mixed dementia is a of combination dementia where there is an occurrence of more than one type of dementia at the same time. Alzheimer’s and vascular dementia are the most commonly seen but other combinations of dementia are also possible. In the case of mixed dementia, it is difficult to diagnose which type of dementia has more of an effect.