Looking out for signs of early onset dementia

Written by: Professor Peter Garrard
Edited by: Cal Murphy

Dementia is a terrible disease no matter what age it strikes, but did you know that it can even affect people in their 40s and 50s? Acclaimed neurologist Professor Peter Garrard is here to explain early onset dementia.

Young onset dementia is loosely defined as cases occurring in people under 65, or at working age. In this age group, the prevalence of dementia is very low, affecting less than 1% of the population. As people age, the incidence increases by about 5% per year; after 90 between a quarter and a third of people will have dementia. It is a disease of ageing – that is to say, ageing is one of the major risk factors.


Signs and symptoms of dementia

In younger patients, the probability of having dementia is very low. Consequently, it is often not suspected and can go undiagnosed for longer. Older people are known to be at increased risk, so dementia is suspected earlier and diagnosed more quickly.

Dementia can be diagnosed when the patient exhibits symptoms of cognitive failure, including the following:

  • Memory impairment
  • Language loss
  • Behavioural change
  • Inability to navigate or use visual apparatus to perform daily tasks

It is important to realise that dementia doesn’t always present with memory problems or forgetfulness. It can also present with visual/navigation problems – this can include difficulty with reading, driving, or navigating around the house. This is often dismissed as indicating visual impairment and the patient is referred on to an optician or ophthalmologist. In reality it is a symptom of visual processing impairment, which is caused by damage within the brain, and must therefore always be taken seriously.

There are also language symptoms: changes in word-finding ability and in understanding more complex words.

Behavioural symptoms are also indicative of dementia. Personalities can change and patients begin to exhibit bizarre behaviours, making normal lives with social and work environments difficult.


Mechanisms of dementia

There are several possible underlying causes and pathologies for dementia that we look for:

  • Alzheimer’s disease – the most common cause overall. However, in the younger onset population, those patients with Alzheimer’s account for maybe one third. Alzheimer’s involves the accumulation of proteins, chiefly amyloid and tau, in the brain.
  • Premature vascular dementia – a large proportion of early-onset cases are caused by this.
  • Non-Alzheimer neurodegenerative conditions – there are two sub-types: tauopathies (in which clumps of the ‘nerve cell scaffolding’ protein tau accumulates, without amyloid, in the brain); and those involving a build-up of a different protein, called TDP43.

While Alzheimer’s tends to affect the posterior regions of the brain, impacting on visual processing and memory, non-Alzheimer neurodegenerative conditions tend to affect frontal areas, causing problems with language and behaviour.

The mechanisms in all these underlying pathologies are unknown, but a proportion (about 5-10% of cases) will be due to inheriting a faulty gene. Such people usually have a family history of dementia. However, the majority of cases are not inherited, and the cause or causes are unknown. The mechanisms leading to sporadic dementia are the focus of intensive research around the world.

Professor Garrard: how to recognise Alzheimer’s disease

Can you prevent dementia?

Risk factors include:

  • Hypertension
  • Smoking
  • Excessive alcohol consumption
  • Obesity
  • Diabetes
  • Lack of exercise

These lower resistance to neurodegenerative disease as you age. However, even by avoiding all of the above, it is impossible to eliminate the incidence of dementia completely.

Homocysteine is a potent risk factor. There is evidence that if you lower homocysteine in Alzheimer’s patients with above-average levels, you can stabilise their cognition, but there needs to be a large clinical trial to prove its benefits.


For more information on dementia or to book an appointment with Professor Garrard, visit his Top Doctors profile.

By Professor Peter Garrard

Professor Peter Garrard is an expert consultant neurologist and active clinician scientist in London, with a focus on linguistic profiles of disorders of the nervous system. He has more than 25 years of clinical experience, including 15 years as an accredited specialist in neurology. His specialist interests include neurological disorders, cognitive disorders, progressive language disorders, frontotemporal dementia, and early-onset dementia.

In 1990, Professor Garrard received his primary medical qualification from the University of Bristol and subsequently undertook his higher medical training in Edinburgh for surgery and Yeovil for medicine. Once in London, he completed his general medical training before taking on specialist training in neurology in 2000. During this time, Professor Garrard completed his PhD at Cambridge University on language abnormalities in Alzheimer's and other dementias as a Medical Research Council clinical training fellow.

Professor Garrard has completed extensive neuroscience research, and currently holds the position of Professor of Neurology at St George's University of London, where his primary research interest is in the early language changes associated with neurodegenerative dementians, such as Alzheimer's. He is deputy director of the Molecular and Clinical Sciences Research Institute at St George's, and also leads an active dementia research laboratory. Additionally, Professor Garrard has continuously taken on educational roles in his field since becoming a member of the General Medical Council.

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