Stages Of Mixed Dementia

Introduction

Mixed dementia is a condition that affects the elderly, those whose ages are above 65 years old. It is a condition in which a person has one or more types of dementia. Mixed dementia is normally classified as 

• A mixture of the abnormal deposition of proteins associated with Alzheimer’s disease and; 
• The blood vessel problems in the brain, which is a characteristic feature of vascular dementia. 

Additionally, mixed dementia is linked with Lewy body dementia. 

The majority of diagnoses for mixed dementia would be the combination of two types of dementias presented above. Several autopsy studies looking at the prevalence of the kinds of mixed dementia cases reported that 36%–50% were diagnosed with Alzheimer’s dementia, 30%–40% reported vascular dementia, and 20%–22% were diagnosed with mixed vascular Alzheimer's disease.¹ 

Mixed dementia has a similar pathogenesis to those affected with Alzheimer’s disease and vascular dementia. So, the information below will focus on the pathogenesis of both conditions mentioned above.

Pathophysiology of Alzheimer’s

The exact cause of Alzheimer’s isn’t fully known, but it’s well known that affected individuals’’ cholinergic neuronal network that serves as the signal network for autonomic, involuntary nervous responses like blood pressure and heart rate are involved.  This network gradually degenerates, and proteins start to accumulateinto plaques and neurofibrillary tangles- defined as the accumulation of tau proteins that form within the neurone. Their function is to stabilise the neurones. 

Due to this, their ability to transmit messages gets gradually impaired, and several cholinergic neurones start to be lost, which causes a reduction in the number of nicotinic receptors in the brain. Moreover, further physiological changes start to occur, like 

• The accumulation of other proteins like beta-amyloid proteins 
• Alterations to glucose metabolism in the brain, and finally
• The cortical membrane (outer layer of the cerebrum) begins to thin out and degenerate

The most common pathological features in affected individuals are micro-infarction, amyloid angiopathy, and white matter and perivascular lesions.²

Pathophysiology of Vascular Dementia

The pathophysiology of Vascular dementia is similar to Alzheimer’s disease. Vascular dementia also impairs cholinergic neurotransmission, reducing the cholinergic nerve terminals, and in turn decreases the activity of choline acetyltransferase in the brain. Choline acetyltransferase is an enzyme that synthesises acetylcholine, responsible for transmission between neurones. Additionally, it degenerates the nicotinic cholinergic neurotransmission with a corresponding reduction in the number of their corresponding receptors. Overall, this causes a decrease in the concentration of acetylcholine in the cerebrospinal fluid.

However, vascular dementia also affects the cerebral blood flow of the brain. It’s known that chronic diseases that affect the vascular system, like hypertension and diabetes, can cause the thickening of the capillary basal membrane and the accumulation of collagen in the vascular endothelium. The vascular vessels would die and there would be a decrease in the number of terminal blood vessels. This ultimately affects the cerebral microvasculature and reduces the blood flow in the cerebrum. So, these changes in the brain’s vasculature cause the damage to slowly snowball and accumulate. This results in hypoperfusion, neuronal death, and cerebral cell death and start the accumulation of beta-amyloid and tau proteins.²

Stages of mixed dementia

The stages of mixed dementia are again similar to other types of dementia, where it’s separated into: early, middle, and late-stage dementia, as determined by DementiaUK.³ However, other information and websites think that it should be similar to the seven stages of vascular dementia.⁴ Here it’ll be categorised as three stages instead of seven. Mixed dementia can progress rapidly, and this progression can depend on factors like age, the type of mixed dementia they were diagnosed with, and current physical and mental health.

Early stage dementia

Early-stage mixed dementia is a stage where the symptoms aren’t as prevalent compared to the latter stages. Many individuals with early-stage mixed dementia will last for months or years. Symptoms can include mild issues with memory and concentration. In particular short-term memory, and the recollection of recent events may be altered, but their memories of their childhood haven’t been significantly affected. Furthermore, they may have some problems with language and communication, which affects their vocabulary, or start to have difficulty responding to conversations. Also, these individuals have difficulties in planning, decision-making, and problem-solving. Finally, they may start to feel frightened, worried, anxious, and depressed in the early stages.

Middle stage 

The middle stage of dementia may start to become more severe and more pronounced. They start to follow their partner or family member around the home. They may start to have uninhibited speech behaviour or perform actions that a normal person would think twice about. Individuals may start to have difficulties sleeping or may start walking during the night. They may start to not recognise that they’re inside their own house. Additionally, may begin to do repetitive behaviour, like rubbing clothes or asking the same questions repeatedly. Affected individuals start to experience an interesting condition called sundowning, which refers to the state of intense anxiety that typically occurs around sunset. Finally, they begin to become more forgetful, talking and muttering to themselves, and they start having problems finding words and understanding sounds. 

A study was done that compares individuals at different stages of Alzheimer's disease/dementia by measuring their cognitive and motor functions.⁵ They found that those individuals diagnosed with moderate Alzheimer’s disease had a significantly lower performance in all cognitive tests compared to those with mild Alzheimer’s disease. The study discussed that there was a greater impairment in individuals with moderate stages of Alzheimer's and an overall cognitive decline as the disease progresses. This is in contrast to the patients with mild stages of Alzheimer’s disease with similar motor function to the healthy elderly.⁵

Late stage

Those who progress to the late stage of mixed dementia have their symptoms fully manifested and even more pronounced that it comes to the point that they can’t live independently. Their communication ability is significantly diminished, and they may only be able to speak a few words. They may lose the concept of time, begin to believe they’re children, and start unsettling in their own home. Soon, they’ll start not recognising their partner, family members, and friends. Finally, the affected individuals as well as their friends and family will start to see physical and mental changes like mobility issues and difficulty eating and drinking. In addition, they may begin to become more susceptible to anxiety, depression and fear, causing them to become distressed, crying, screaming, and shouting.

The same investigation study mentioned above found that moderate and severe stages of Alzheimer’s disease were at higher risk of functional loss and falls. Furthermore, they found that severely affected individuals had a decrease in instrumental activities of daily living (IADL), and basic activities of daily living (BADL), which overlaps with individuals at the moderate stage of the disease.⁵ Examples of IADL include housekeeping, cooking food, and BADL include eating, hygiene work.

A UK study looks at the quality of life of affected individuals at different stages of dementia.⁶ They interviewed 157 participants, and like the study above, they found that performances were lower in moderate and severe stages of dementia. Also, individuals suffering from severe dementia required the highest degree of assistance for activities like toileting, transfer, and feeding. Those individuals with mild and moderate dementia had a greater ability to function independently compared to those with severe dementia.⁶

How can we help those with mixed dementia?

According to Alzheimers.gov, caring for those with mixed dementia can be difficult, especially as the disease progresses, since they won’t be able to do basic tasks that healthy individuals can do. Here are the tips they’ve suggested for early and progressing mixed dementia.

• Their routine of bathing, eating, and sleeping should be kept to the same time every day
• Write down a to-do list for those affected individuals to help them remember daily tasks and important events they had to do on the day
• Set a reminder system to help them remember to take their medication regularly
• When speaking to them, be respectful and provide a step-by-step list of their daily activities
• Serve meals in a consistent and familiar place and give them enough time to eat

Summary

In conclusion, mixed dementia is a condition that affects the elderly. It’s caused by the accumulation of proteins like tau and beta-amyloid protein, which cause the degeneration of neurones and cortex membranes.

Mixed dementia can be classified as Alzheimer’s disease, vascular dementia, or a combination of both. Mixed dementia can be divided into three stages: early, middle, and late stages. 

The early stages of dementia have mild problems with:

• Concentration; short-term memory may be affected
• Communication problems may begin to deteriorate
• Planning, problem-solving, and decision-making may be affected

When individuals progress to the middle stage, they begin to have trouble sleeping, start behaving irrationally, and typically become more and more forgetful. 

Finally, in the late stages of dementia, their ability to communicate completely reduces and they have sudden physical changes that stop them from performing their daily tasks.