What is Dementia?

The most common cause of dementia is Alzheimer's disease. Common symptoms of Alzheimer's disease include:

• memory problems, such as regularly forgetting recent events, names and faces

• asking questions repetitively

• increasing difficulties with tasks and activities that require organisation and planning

• becoming confused in unfamiliar environments

• difficulty finding the right words

• difficulty with numbers and/or handling money in shops

• becoming more withdrawn or anxious

Vascular dementia is the second most common cause of dementia, after Alzheimer's. Some people have both vascular dementia and Alzheimer's disease, often called "mixed dementia".

Symptoms of vascular dementia are similar to Alzheimer's disease, although memory loss may not be as obvious in the early stages.

Symptoms can sometimes develop suddenly and quickly get worse, but they can also develop gradually over many months or years.

Specific symptoms can include:

• stroke-like symptoms: including muscle weakness or temporary paralysis on one side of the body (these symptoms require urgent medical attention)

• movement problems – difficulty walking or a change in the way a person walks

• thinking problems – having difficulty with attention, planning and reasoning

• mood changes – depression and a tendency to become more emotional

Dementia with Lewy bodies has many of the symptoms of Alzheimer's disease, and people with the condition typically also experience:

• periods of being alert or drowsy, or fluctuating levels of confusion

• visual hallucinations (seeing things that are not there)

• becoming slower in their physical movements

• repeated falls and fainting

• sleep disturbances

Find out more about dementia with Lewy bodies.

Although Alzheimer's disease is still the most common type of dementia in people under 65, a higher percentage of people in this age group may develop frontotemporal dementia than older people. Most cases are diagnosed in people aged 45-65.

Early symptoms of frontotemporal dementia may include:

• personality changes – reduced sensitivity to others' feelings, making people seem cold and unfeeling

• lack of social awareness – making inappropriate jokes or showing a lack of tact, though some people may become very withdrawn and apathetic

• language problems – difficulty finding the right words or understanding them

• becoming obsessive – such as developing fads for unusual foods, overeating and drinking

Posterior cortical atrophy (PCA), also called Benson’s syndrome, is a rare, visual variant of Alzheimer’s disease. It affects areas in the back of the brain responsible for spatial perception, complex visual processing, spelling and calculation.

In the vast majority of PCA cases, the underlying cause is Alzheimer’s disease, and the brain tissue at autopsy shows an abnormal accumulation of the proteins amyloid and tau that form the plaques and tangles seen in Alzheimer’s disease. Although PCA is almost always caused by Alzheimer’s disease, it can result from other diseases including dementia with Lewy bodies and Creutzfeldt-Jakob disease. PCA is thought to affect less than 5% of people with Alzheimer’s disease, although epidemiological studies are lacking and PCA has been under-recognized in the past.

People with PCA may often go to see an eye doctor first, thinking that their difficulties are due to a problem with their eyes and that they may need new glasses. Visual impairment commonly develops as people get older, and in most cases, a decline in vision is due to this natural aging process. In people with PCA, the visual problems are not due to problems with their eyes. Rather, the shrinking brain can no longer interpret and process the information received from the person’s healthy eyes.

Read more about PCA

As dementia progresses, memory loss and difficulties with communication often become severe. In the later stages, the person is likely to neglect their own health, and require constant care and attention.

The most common symptoms of advanced dementia include:

• memory problems – people may not recognise close family and friends, or remember where they live or where they are

• communication problems – some people may eventually lose the ability to speak altogether. Using non-verbal means of communication, such as facial expressions, touch and gestures, can help

• mobility problems – many people become less able to move about unaided. Some may eventually become unable to walk and require a wheelchair or be confined to bed

• behavioural problems – a significant number of people will develop what are known as "behavioural and psychological symptoms of dementia". These may include increased agitation, depressive symptoms, anxiety, wandering, aggression, or sometimes hallucinations

• bladder incontinence is common in the later stages of dementia, and some people will also experience bowel incontinence

• appetite and weight loss problems are both common in advanced dementia. Many people have trouble eating or swallowing, and this can lead to choking, chest infections and other problems.

Wernicke-Korsakoff (WK) syndrome is a serious brain condition that is usually, but not exclusively, associated with chronic alcohol misuse and severe alcohol use disorder (AUD). The prevalence of WK syndrome across populations is not well established, and researchers estimate that it may remain undiagnosed in approximately 80 percent of patients.

WK syndrome involves two different brain disorders that often occur together: Wernicke’s disease and Korsakoff’s psychosis. They result from brain damage associated with AUD, combined with vitamin B1 (thiamine) deficiency. In people with severe AUD, poor nutrition decreases the ability of the gut to absorb thiamine from food and, therefore, increases the chance of developing WK syndrome. Without treatment, WK syndrome can be disabling, produce permanent memory loss, and be life-threatening.

Symptoms of Wernicke’s disease include: 

• Confusion 

• Lack of energy, hypothermia, low blood pressure, or coma

• Lack of muscle coordination that can affect posture and balance and can lead to tremors (i.e., involuntary movements in one or more parts of the body)  

• Vision problems such as abnormal eye movements (e.g., back and forth movements called nystagmus), double vision, misaligned or crossed eyes, and eyelid drooping

Although some symptoms of Wernicke’s disease such as muscle and vision problems are reversible with prompt thiamine treatment, other symptoms may respond more slowly or may not be completely reversible. Without prompt treatment, Wernicke’s disease can progress to Korsakoff’s psychosis, which is not reversible.

Symptoms of Korsakoff’s psychosis include those listed above, as well as: 

• Potentially severe, irreversible memory impairments, including problems forming new memories (called anterograde amnesia) and recalling memories

• Making up inaccurate stories about events (i.e., confabulation) or remembering events incorrectly

• Experiencing hallucinations (i.e., seeing or hearing things that are not really there)

• Repetitious speech and actions

• Problems with decision making as well as planning, organizing, and completing tasks

• Lack of motivation and emotional apathy