04 Dementia-related conditions

Dementia-related conditions

There are a number of conditions which can increase the risk of dementia, directly cause dementia and mimic similar symptoms of dementia.


After living with Parkinson’s for a sustained period of time, the potential to develop dementia increases.

There are to main types of dementia which affect people living with Parkinson’s – Parkinson’s dementia and dementia with Lewy bodies which share similar causes. The main difference is that problems with movement occur before cognitive symptoms in Parkinson’s dementia, but in dementia with Lewy bodies, cognitive symptoms occur before, or coincide with, problems with movement. With both types of dementia, Lewy bodies spread from the brain stem to other structures in the brain, disrupting the cells’ ability to transmit information and causing them to die.

Symptoms of dementia associated with Parkinson’s disease vary with each individual from one day to the next. The most common symptoms are memory loss, impaired thought processing and difficulties in carrying out everyday tasks. Someone living with Parkinson’s and dementia may become obsessive and struggle to control their emotions. It’s not uncommon for symptoms such as visual hallucinations (seeing things which are not really there) to also occur.

Corticobasal degeneration (CBD)

Corticobasal degeneration is a rare disease typically affecting people between the ages of 60 and 80 and causes various symptoms of dementia to develop. With CBD, areas of the brain such as the cortex (outer structures of the brain, sometimes referred to as grey matter) and the basal ganglia (inner structure) become damaged and begin to shrink. Medical and scientific research have not yet been able to provide us with an answer to what causes CBD, but an excessive level of an abnormal protein called tau is thought to be connected.

The symptoms of CBD vary with how progressed the condition is. Initial include problems with movement, stiffness and a failure to control hand movement on one side. Later stages of CBD develop other symptoms, such as a loss of balance & coordination, and difficulties speaking as well as cognitive symptoms associated with dementia, including problems with memory and thinking.


Huntington’s disease is hereditary and caused by inheriting a defective gene. This defective gene causes abnormal movements and problems with coordination. As Huntington’s progresses, symptoms typically associated with dementia begin to develop such as difficulties with thought processing, concentration, planning, controlling emotions and behaviour, as well as a decline in short-term memory. The type of dementia associated with Huntington’s differs from Alzheimer’s disease in that those affected continue to recognise people and places until the very late stages of the illness.

Normal pressure hydrocephalus (NPH)

Normal pressure hydrocephalus (sometimes also referred to as Hakim’s syndrome and symptomatic hydrocephalus) is caused by excessive cerebrospinal fluid accumulating in the brain’s structures. Hollow fluid-filled chambers in the brain called ventricles become filled with cerebrospinal fluid and as the ventricles swell, they can damage nearby brain tissue and disrupt the cells’ ability to communicate with one another. NPH shares symptoms with Alzheimer’s disease, including declining thought processes, planning, decision-making and changes in personality and behaviour. NPH can also cause difficulty in walking – sometimes compared to walking on a boat with the body bent forward, legs held apart and shuffling foot movements. Later stages of NPH usually affect bladder control and the structures of the brain become affected. Treatment is available for NPH, which involves draining excess fluid in a surgical procedure. Although the success of this treatment varies depending on how early the condition is diagnosed, some people make an almost complete recovery.

Posterior cortical atrophy (PCA)

PCA is also sometimes referred to as Benson’s syndrome and it is a rare degenerative condition in which damage occurs at the back (posterior region) of the brain. In the majority of people diagnosed with PCA, Alzheimer’s is identified as the cause. In the initial stages, PCA usually causes problems with vision and comprehension, such as recognising faces and objects, and also problems with literacy and numeracy. As the disease progresses, a person living with PCA is likely to develop symptoms typical of Alzheimer’s such as confusion and memory loss.

Progressive supranuclear palsy (PSP)

Sometimes known as Steele-Richardson-Olszewski syndrome, progressive supranuclear palsy is a rare and progressive movement disorder which affects many areas of the brain. Medical and scientific research has not yet established the cause of PSP, but an abnormal protein deposit called tau is thought to be connected. These abnormal protein deposits restrict the nerve cells in the brain from communicating with one another, causing symptoms such as paralysis of eye movements, double vision, stiff or slow movements, difficulties in speaking and swallowing, and changes in behaviour and personality.

Whilst a small proportion of people with frontotemporal dementia sometimes develop PSP as an ‘overlapping’ condition, in most cases, the person is more likely to be described as ‘experiencing cognitive difficulties’ rather than ‘having dementia’. Although a person living with PSP may experience problems with their speed of thinking and memory, they will remain aware of what is going on around them which is a key difference between PSP and dementia.

Multiple sclerosis

The term ‘dementia’ is not generally used in association with multiple sclerosis. Although a person living with multiple sclerosis may experience a decline in their cognitive abilities such as their memory, concentration and problem solving, these symptoms are usually less severe as in other forms of dementia. The phrase ‘experiencing cognitive difficulties’ is more commonplace when describing the condition of a person living with multiple sclerosis.