Posterior cortical atrophy (PCA) means ‘back of the brain shrinkage’ and it refers to the progressive loss of brain cells, particularly in brain regions that process visual and sensory information.
These regions are called the occipital and parietal lobes. It is a rare form of dementia which can initially cause difficulties with seeing what and where things are, for example, when driving or reading, with interpreting, locating, or navigating things or places. The symptoms of PCA usually begin before the age of 65 and people are often in their mid-50s or early 60s when they first experience symptoms. However, PCA can also affect older people and it can take a long time for people to receive the correct diagnosis because of the unusual or atypical symptoms.
Living with PCA
Get advice and information to help you, your family and friends to live well with PCA.
There are some other underlying conditions that can cause PCA. These include Lewy body dementia (LBD), and in very rare cases, corticobasal syndrome (CBS) and Creutzfeldt-Jakob disease (CJD). Very little is known about why PCA affects some people and not others, nor how many people there are living with PCA. This is because the condition is rare, the age at onset is younger (compared to Alzheimer’s disease, for example) and the symptoms are unusual and variable. Some studies estimate that about 5% of people with Alzheimer’s disease have PCA. Research on gender differences is also mixed, some studies have reported that PCA affects both men and women equally while others suggest an over-representation among women.
Although in PCA the primary symptoms affect vision, these problems are due to changes in the brain rather than the eyes, and so an optician or ophthalmologist will not usually get to the root of the problem. In PCA the problem is that the affected part of the brain is unable to interpret the information sent to it by healthy eyes. People living with PCA often do not have problems with their memory and language abilities in the early stages. Over times as the disease progresses, there will be an increase in the number or impact of symptoms. This can take several years and will impact vision and/or literacy skills (including spelling, writing and arithmetic) as well as memory and other cognitive abilities. It is also important to remember that the experience of PCA differs from one person to the next. The pattern of symptoms that someone has depends on how and where the brain is affected.
To understand some of these difficulties, you can watch this short film directed by Simon Ball, ‘Do I see what you see?’ narrated by people living with PCA and their partners.
Some of the first symptoms of PCA include:
- Problems with reading (for example, difficulty following lines of text, words jumbling up, or with certain text formats and sizes)
- Difficulties with coordination and spatial awareness (such as picking up objects, dressing, selecting the correct numbers on a telephone)
- Visual problems (including blurred vision, perceiving objects amongst clutter, double vision, difficulty focusing as well as difficulty perceiving more than one object at the same time, known as simultanagnosia)
- Problems with judging distances and speeds (for example with moving traffic, walking onto escalators, descending stairs)
- Difficulty recognizing faces (including TV characters, friends, relatives)
- Light sensitivity and unusual colour experiences (such as washes of colour when driving at night)
PCA can affect people in different ways and vision is not always the first, or only, area of difficulty for people living with PCA. Literacy, numeracy, and certain coordination skills may also be affected and cause difficulties with tasks such as recalling the exact spelling of words, writing, remembering the shape or name of particular letters or numbers, mental arithmetic, dealing with money and small change, making gestures (such as waving or giving thumbs up), using particular tools, kitchenware or implements (for example scissors, cutlery, glasses) or getting dressed.
In the mid-stages, people living with PCA may retain understanding of the purpose of everyday activities, but they may need significant help as their visual impairment progresses. As PCA progresses, vision can become severely impaired. The world may be viewed in a distorted way (for example, as pieces of a puzzle or as if through a fractured mirror). The person may notice small details but struggle to understand the relationship between objects in a given space. This can lead to:
Requiring help with most or all everyday tasks (including personal care owing to difficulties with visual and spatial awareness)
Difficulty performing spatial commands and actions (such as ‘turn round’, ‘step forward’)
Requiring support or supervision when walking (difficulty in detecting the edges of pavements, paths, and steps; a tendency to shuffle, stoop or lean)
At this stage, many people with PCA are registered as blind, which means that they need help with most visually-guided activities. Some people may have problems with other senses, including increased sensitivity to pain and temperature (especially in the head, hands and feet), changes in the sense of hearing (such as becoming more sensitive to certain sounds), sense of imbalance or instability or experiencing little jerky movements.