What's the Difference?

We are often asked "What's the difference between Alzheimer's (AD) and dementia." Or between Lewy body dementia  and Alzheimer's. Or less often, between LBD and Parkinson's. The latest one was between LBD and Multiple System Atrophy. Today's blog is a list of definitions, along with how these conditions relate with each other. It is very basic and for many regular readers, the information in this blog and the next will likely be redundant but sadly, new people are joining the ranks of dementia care partners every day. I hope these blogs will help you sort out what dementia is and isn't.

Cognitive abilities: Skills we use to learn, remember, problem solve and pay attention, control impulses and communicate.

Syndrome: A collection of symptoms that occur together and characterize a condition but the underlying cause is not necessarily known.

Dementia: A syndrome, where there is a decline of at least two cognitive abilities severe enough to interfere with daily life. There are over seventy (70!) underlying causes of dementia. About 95% of these causes are Alzheimer's, Lewy body dementia, vascular dementia, and frontotemporal dementia. These dementias tend to occur together and a person seldom has only one kind. There are other causes, such as brain injury, hydrocephalus, brain cancer or HIV. Most dementias are not reversible but some, such as vitamin deficiencies, thyroid abnormalities and medical interactions, are. This makes obtaining a diagnosis important. Most dementias are progressive, but some are episodic.

Progressive vs. Episodic: Damage from progressive dementias causes a gradual degeneration. Damage from episodic dementias is an individual event and doesn't change. However, many events may occur closely in time to each other, making the dementia to appear to be progressive. An important difference is that episodic dementia can be kept from increasing if the cause is removed.

Most Common Types of Dementia:

Mixed dementia: The percentages for each dementia below add up to much more than 100% because most dementias are mixed. Where one kind dominates, or where a doctor is more familiar with one kind, that's what will be diagnosed. As all dementias progress, most symptoms will eventually be affected and they dementias become very similar.

Alzheimer's Disease (AD): Progressive. Up to 80% of all dementias. It attacks and kills brain cells and the brain actually shrinks in size. Early symptoms are cognitive--mainly memory loss.

Lewy Body Dementia (LBD): Progressive. Progressive. Up to 30%. It attacks certain messenger chemicals called neurotransmitters and weakens or kills them. It is more invasive than AD and has many more symptoms. Early symptoms vary from constipation to hallucinations to mobility issues and more.

Vascular dementia (VaD): Episodic. Up to 30%. Occurs when the brain doesn't get adequate oxygen, usually from a stroke. Many small strokes can cause the dementia to look progressive. Symptoms depend on the area of the brain deprived of oxygen. Lifestyle changes can often prevent further episodes and stop the dementia from progressing.

Frontotemporal dementia (FTD): Progressive. Up to 5%. It affects the frontal temporal of the cortex, where empathy is generated. Memory, and other cognitive skills may remain, but one's ability to see another's view or pain fades.

Next week the blog will be about the differences between LBD and other conditions such as PD and MSA. It will also discuss further the different types of LBD.

* Acronyms:
LBD: Lewy body dementia
AD: Alzheimer's disease
VaD: Vascular dementia
FTD: Frontotemporal dementia
MSA: Multisystem atrophy
PlwD: person living with dementia
PlwLBD: person living with LBD
DLB: dementia with Lewy bodies
PD: Parkinson's disease
PDD: Parkinson's disease with dementia
MCI: mild cognitive impairment
MCI-LB: the form of MCI that precedes LBD
BPSD: behavioral and psychological symptoms of dementia

For information about Lewy body disorders, read our books:
A Caregivers’ Guide to Lewy Body Dementia
Managing Cognitive Issues in Parkinson's and Lewy Body Dementia

Helen and James Whitworth are not doctors, lawyers or social workers. As informed caregivers, they share the information here for educational purposes only. It should never be used instead of a professional's advice.