Thinking, memory, planning, perception and attention
Parkinson's disease can effect cognitive changes across these areas, including difficulty with judging distances or driving, dual-tasking and overall poor concentration.
When these changes become severe enough to affect daily activities, they are referred to as Parkinson's disease dementia, a condition closely related to, but clinically distinguished from, dementia with Lewy bodies.
Key points
- Cognitive changes range from mild difficulties with planning and attention through to dementia.
- In Parkinson's disease dementia, movement symptoms come first, with thinking changes typically developing at least a year later.
- Visual hallucinations, fluctuating attention, sleep disturbance and movement symptoms often occur alongside cognitive change in these related conditions.
- Medication choices for cognition are limited, but can be helpful when symptoms are more severe or associated with other clinical symptoms such as hallucinations.
Next steps:
Cognitive changes in Parkinson's disease can include:
- difficulty judging distances or navigating unfamiliar environments
- difficulty with planning, multitasking or decision-making
- memory difficulties, particularly with recalling recent events
- slowed thinking or processing speed
- word-finding difficulty.
When cognitive changes occur alongside Lewy body involvement, additional features may include:
- detailed visual hallucinations, often of people or animals, which don't always cause distress
- fluctuating attention and alertness, which can change hour to hour; a person may seem clear and engaged one moment, then confused or drowsy the next
- sleep disturbance, including REM sleep behaviour disorder, where a person physically acts out their dreams.
Parkinson's disease dementia and Lewy body dementia are closely related conditions that share the same underlying brain change: build-up of a protein called alpha-synuclein.
Doctors distinguish between them using key clinical criteria, including the timing and order in which symptoms appear.
Not all cognitive change in someone with Parkinson's disease is due to the disease itself. Other contributors to consider include:
- depression, which can affect concentration and processing speed
- infection (such as a urinary tract infection) or dehydration, which can cause an acute, reversible confusional state
- medication side effects
- poor sleep
- other causes of dementia, such as Alzheimer's disease or vascular dementia.
Assessment is based on a history from the patient and, where possible, family members, covering the pattern and timing of symptoms relative to changes in movement.
Formal cognitive testing may be used to characterise the type and severity of difficulty. Your doctor will also look for reversible contributors such as infection, medication effects or depression, and will consider whether there is a pattern of neurodegeneration.
- Treat reversible triggers first – infection, dehydration, poor sleep and depression should be identified and addressed, as these can worsen cognitive symptoms independently of the underlying condition.
- Set up strategies – online cognitive training, routines and clear communication can help improve cognition.
- Medicines for memory and thinking – some medicines may help with symptoms for a period of time, though they do not stop the underlying condition.
- Considerations around driving – this might require specialist ‘on-road’ assessment or the restriction of licence privileges.
- Team-based support – ongoing input from a neurologist, GP, and where appropriate a psychologist, speech pathologist, or occupational therapist can help manage day-to-day impact, emphasising that help is available and collaborative care is effective.
When to consider specialist review
Speak with your neurologist or GP if thinking or memory changes are:
- new, worsening or affecting daily independence
- accompanied by hallucinations, fluctuating alertness or significant sleep disturbance.
You may need a more detailed specialist assessment for these symptoms.
When to seek urgent help
Seek urgent medical attention for a sudden or rapid worsening of confusion or thinking, as this can indicate a treatable trigger such as:
- dehydration
- infection
- medication effect.
These symptoms require prompt assessment rather than a routine review.