It's well understood that the symptoms of Parkinson's disease is caused by a lack of dopamine affecting the substantial nigra within the brain leading to tell-tale tremors and shuffling gait. But less well appreciated by the public is the impulsivity issues and emotional ramifications of this disease which can lead to criminal behaviour.
Jasvinder Singh a neuropsychiatrist from Newcastle Upon Tyne in an article entitled:
Impulse Control Disorder, Parkinson’s disease and criminality? mentions some interesting findings related to this issue. If the patient is taking dopamine replacement therapy or if the patient abuses the dopamine replacements can suffer a bewildering array of impulsive behaviours.
Some of these behaviours include:
Compulsive sexual behaviour
These can lead to a dramatic breakdown of familial units and marriages.
"The prevalence estimates of impulse control disorders in Parkinson’s disease has been estimated to be 13.6% and it ranges from 1.7% to 6.1% for gambling, 2% to 4% for compulsive sexual behaviour and 0.4 to 3% for compulsive buying."
It's not to be thought that the dopamine agonists or treatments are exclusively to blame as it's only a relatively minor subset of Parkinson's patients who will experience these issues with impulse control.
The article also illustrates the above issue with a case study of a 55-year old man who experienced such impulse control issues and began displaying inappropriate sexual conduct towards females in public spaces.
It's an interesting case and well worth taking the time to read.