Introduction

The clinical presentation of dementia patients has helped categorise the four main subtypes: AD, VD, DLB and FTD. These are now discussed in more detail.

For clarity the descriptions each relate to a single subtype, but in clinical practice a mixed pattern is often seen.

Probable Alzheimer’s disease

Characteristics of AD

Progressive cognitive impairment and memory loss established by clinical and neuropsychological testing with all of the following:

• Impairment of two, or more, areas of cognition
• Onset between the ages of 40 and 90 years
• No other disease capable of producing a dementia syndrome or delirium
• This is the commonest form of dementia

A possible diagnosis of AD may be made if the presentation or progression is atypical, but no other dementia syndromes or disease states are present.

How AD affects the patient

Initially, people may seem slightly more forgetful than otherwise expected for their age. However, as the disease progresses, sufferers may get lost in familiar settings and lose the ability to perform tasks they previously enjoyed such as cooking and playing cards.

They may become repetitive, telling the same story time and time again, neglectful of their personal hygiene or have difficulties making decisions.

As their impairment becomes more severe, they may struggle to recognise family members and have difficulty communicating as their speech deteriorates.

Sudden onset of functional impairment, focal neurological signs, seizures or gait changes are unlikely to be due to Alzheimer’s disease.

Learning Bite

The hallmark of Alzheimer’s disease is a gradual but relentless impairment of memory function.

Probable vascular dementia

Characteristics of VD

Cognitive decline and memory loss established by clinical and neuropsychological testing combined with:

• Impairment sufficient to affect activities of daily living
• Impairment of two or more areas of cognition
• No other disease capable of producing a dementia syndrome or delirium

AND

Cerebrovascular disease defined as either:

• Presence of focal neurological signs
• Evidence of cerebrovascular disease on brain imaging, CT or MRI

AND

A relationship between the above components defined as either:

• Onset of dementia within three months following a recognised stroke
• Abrupt deterioration in cognitive functions or fluctuating, stepwise progression of cognitive deficits

How VD affects the patient

Classically, people with VD will suffer with cognitive impairments within three months of an acute neurological event.

Deteriorations in function may be abrupt and stepwise, affecting their memory, attention and intellect. They commonly have mood and behavioural changes, which may make them aggressive and difficult to care for at home.

The effects of dementia on their activities of daily living are separate to but compound the impairment caused by their focal neurological deficit(s).

Progressive memory loss and changes in speech or motor function are rarely seen in VD without evidence of corresponding lesions on imaging.

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Typically, patients with VD develop symptoms within three months of an acute neurological event i.e. stroke. Deterioration is stepwise and abrupt. Mood swings are common.

Probable dementia with Lewy Bodies

Characteristics of DLB

Progressive cognitive decline with:

• Impairment sufficient to affect activities of daily living
• Prominent deficits of attention, frontal-subcortical skills and visuospatial function
• No other disease capable of producing a dementia syndrome or delirium

AND

Two of the following:

• Fluctuating cognition with pronounced variations in attention and alertness
• Recurrent, visual hallucinations that are typically well formed and detailed
• Spontaneous motor features of parkinsonism

How DLB affects the patient

Sufferers of DLB may present with varying levels of alertness such as excessive daytime drowsiness and long daytime naps. Their cognitive level may swing abruptly from being relatively good to poor.

Parkinsonian features are common in the early stages of the disease, in contrast to AD where they may only occur later in the dementia syndrome.

Other features of DLB include repeated falls, syncope, transient loss of consciousness, neuroleptic sensitivity, systematised delusions and hallucinations in other modalities.

Focal neurological deficits, or evidence of cerebrovascular disease on brain imaging, make a diagnosis of DLB unlikely.

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Patients with DLB classically suffer with excessive somnolence, abrupt swings in cognitive function and features of Parkinson’s disease.

Probable frontotemporal dementia

Characteristics of FTD

Progressive, gradual cognitive decline with:

• Early and progressive change in personality or language
• Impairment sufficient to affect activities of daily living
• No other disease capable of producing a dementia syndrome or delirium
• No disturbance better accounted for by a psychiatric diagnosis

How FTD affects the patient

People in the early stages of FTD may have difficulties with social and personal conduct, which may seem impulsive or inappropriate, often with frustrated outbursts.

Their actions may cause harm such as shop lifting or jumping from a moving car, and can be sexual in nature.

Later, they may become repetitive or compulsive over certain acts with little insight into their problems.

Their expression of language may be affected early on, progressing to affect reading and writing, although their understanding is often preserved.

Sufferers may become virtually mute.

Learning Bite

Patients with FTD frequently exhibit problems with their behaviour and spoken communication.