Parkinson’s Disease: Where did my habits go?  — Professor Peter Redgrave MSc, PhD — 10th August 2015.

RedgraveProfessor Peter Redgrave works at the Sheffield University and lec­tures in the Department of Psychology. He says that his research philo­sophy assumes that to dia­gnose and cor­rect what has gone wrong in a com­plic­ated system like the brain, it is help­ful to have a good under­stand­ing of its normal func­tion. In his talk he explained what Parkinson’s dis­ease is, what causes it and what meth­ods are being used to con­trol it.

It is a neur­o­lo­gical dis­ease res­ult­ing in the inab­il­ity to ini­ti­ate move­ment (Akinesia), it causes slow move­ments (Bradykinesia) and res­ults in a res­ist­ance to pass­ive move­ments (Rigidity), and finally, tremors. Patients often exhibit a for­ward tilt of the head, rigid­ity and trem­bling of the head, a mask-like face, reduced arm swinging, a shuff­ling gait with short steps, and rigid­ity and trem­bling of the extremit­ies.

Parkinson’s is the second most common degen­er­at­ive dis­ease after Alzheimers. About  0.3% of the pop­u­la­tion of indus­tri­al­ised coun­tries suffer from it. It is more likely as people age:  1% over 60  and 4% over 80. However 5 — 10% of cases have young onset, between 20 and 50 years. There does not seem to be any pat­tern to its cause, although clusters of cases do occur in areas of the world.  One was near to a wood pulp­ing works in the USA, sug­gest­ing a chem­ical pol­lu­tion cause.  Is it an indus­trial dis­ease?  It did not appear in his­tor­ical accounts before the Industrial Revolution, but did appear before the dis­cov­ery of elec­tri­city, so it prob­ably is not linked to elec­trical sig­nals, radio waves, tv sig­nals or mobile phones trans­mis­sions.

Parkinson’s  dis­ease affects the  part of the brain called the basal gan­glion, which is crit­ic­ally involved in select­ing actions. The  Basil Ganglion has been found in ver­teb­rate anim­als for 400 mil­lion years.

The brain has two types of beha­vi­oural con­trol sys­tems. Goal dir­ec­ted con­trol and habitual con­trol. Prof. Redgrave gave the example of a learner driver con­cen­trat­ing on steer­ing and watch­ing the traffic and trying to judge when to change gear.  He is using goal dir­ec­ted con­trol. Whilst an exper­i­enced driver will ‘auto­mat­ic­ally’ change gear when engine revs or car speed ‘tells’ him it should happen.  Most of the time the driver will not know what gear the car is in but it will ‘feel’ right, and this driver is using habitual con­trol.

Another example was when he bought a new house.  He had turned left for many years at a junc­tion to go to his old house, but he needed to go straight on to get to his new house.  On his way home he used goal dir­ec­ted con­trol to get to his even­ing meal and went straight on, but if he gets dis­trac­ted by think­ing of a prob­lem at work or of the talk he has to give to Probus, he could some­times use habitual con­trol and turn left on the route he had taken for years before.

Dopamine cells pro­duce a neur­o­trans­mit­ter called dopam­ine, which is crit­ical in resolv­ing these options, and the dopam­ine cells appear to be dying in people with Parkinson’s dis­ease. It seems that, when the dopam­ine cells die  the habitual con­trol system no longer works.  Many of the habits of the pre­vi­ous life are lost. This seems to explain the shuff­ling gait because the person has to con­cen­trate on how and where to put his feet and keep his bal­ance at the same time.  He has lost the ‘habit’ of walk­ing.  He will often stop when walk­ing around his own home to con­cen­trate on how to nego­ti­ate around the fur­niture. He may have lost the habit of work­ing a zip, of fasten­ing  but­tons or of tying shoe laces.

It can be treated using Dopamine- but they are only effect­ive for 5 to 7 years and during this period the dosage has to be increased  because disk­inesea pro­gress­ively gets worse. Another treat­ment is called Basal Ganglion Lesions which is an oper­a­tion where small parts of the brain are removed. Deep brain stim­u­la­tion is also effect­ive but can be very dan­ger­ous. It involves insert­ing an elec­trode into the brain and send­ing a small cur­rent to a very spe­cific area pro­du­cing seem­ingly mira­cu­lous res­ults. However if the elec­trode is not placed exactly at the right place it can have dis­astrous. For this reason it is con­sidered only for very severe cases because if the elec­trode is not placed exactly where it needs to go, the patient will be no worse off than before.  However, with new tech­no­lo­gies and more accur­ate meth­ods of scan­ning the body, this may become the treat­ment of the future.