Parkinson’s disease

Solicitors often request mental capacity assessments for people living with Parkinson’s when they make a will or make a large financial transaction. This is because Parkinson’s can cause cognitive impairment or dementia but does not always do so. The medications used to treat Parkinson’s can also cause hallucinations.

What is Parkinson’s disease?

Parkinson’s disease is a degenerative condition of dopamine - producing brain cells in a part of the brain called the substantial nigra. The condition primarily affects motor function, its hallmarks being a ‘pill rolling’ tremor in the hands, rigidity, slow movements (bradykinesia) and soft speech.

It generally starts in mid - life and gets worse with time, although many people respond well to the medications used to treat it. The mainstay treatment is levodopa which is converted into dopamine in the brain. This helps with the motor symptoms of tremor and rigidity.

Parkinson’s dementia

Whilst not everyone with Parkinson’s will develop dementia, a significant proportion will, especially those living with the condition for a long time. Parkinson’s disease dementia occurs in people already living with Parkinson’s; the cognitive dysfunction typically starts years after the motor symptoms.

The other type of dementia occurring in those with Parkinson’s is dementia with Lewy bodies. It typically starts at the same time or before the motor symptoms of Parkinson’s. Lewy bodies are clumps of an abnormal protein called alpha - synuclein that build up in brain cells causing them to malfunction and die. Lewy bodies in the substantia nigra cause the movement disorder of Parkinson’s e.g. tremor, rigidity etc. Cognitive symptoms appear when the Lewy bodies are present in the areas of the brain involved in thought processes etc.

Visual hallucinations are a prominent feature of the dementias associated with Parkinson’s.