Brain Functioning and Personality Changes in Parkinson’s Disease

Parkinson’s disease is a chronic progressive neurodegenerative disorder affecting millions of people all over the world. It is caused by the lack of neurotransmitter dopamine in the brain. This neurotransmitter is responsible to control the part of brain incharge of the control movement, emotional response and the ability to feel pleasure and pain. The deficiency of dopamine act synergistically with the increase in the amount free radicals in the body and bring about the physical manifestation of the disease.

The symptoms might appear anytime, but majority of the patients affected are usually above 50 years and rarely below 30 years of age. Although the characteristic symptoms of Parkinson’s disease (PD) involve motor functions such as tremor, rigidity, slowness of movement and loss of postural reflex, there are other neurological and psychiatric symptoms present in later stages of the disease which point to definite changes in brain function and personality of PD patients.

Cognitive Abilities in Parkinson’s Disease

Cognition relates to higher level functions of the brain and may be defined as the mental process involved in gaining knowledge and understanding, which includes the process of thinking, knowing, learning, remembering, decision making, judging and problem solving. Language, imagination, perception and planning are the necessary components.

People with PD often have trouble processing two cognitive acts simultaneously. Mild cognitive impairment may be present in most people with PD. Stress, depression, sleep disturbances, or medication can lead to such changes. Not only the dopaminergic pathways but also other pathways associated with the emotion and cognition such as the serotonergic, adrenergic, cholinergic, and frontal dopaminergic pathways are also variably destructed in the Parkinson’s disease.

Many non-motor aspects of Parkinson’s disease includes depression, impulsive control disorders, drug induced psychosis, anxiety, sleep disturbances, and cognitive impairment. Cognitive disturbances, as well as mood and behavior alterations, can be as traumatic and frustrating as any physical problem, both for the patient as well as the caregiver. They even complicate the clinical management of the disease and are responsible for the poor quality of life for the patients and financial burden on their care-givers.

Cognitive deficits can be present even in the early stages of Parkinson’s disease, gradually worsening as the disease progresses, and may ultimately lead to dementia. A person with PD is at a greater risk of developing dementia and this risk gradually increases in proportion to the duration of the disease. The cognitive deficits seen in PD patients (subcortical dementia) are similar to those caused by frontal lobe damage. Due to the degeneration of the cells of the part of the brain known as substantia nigra in the basal ganglia, there is deficiency of the chemical transmitter dopamine. As a result, there is dysfunction of the circuits connecting the frontal lobe of the brain and the basal ganglia, causing problems with memory, language, concentration, attention, visuo-spatial functions, and executive function of the brain.

Depression in Parkinson’s Disease

Depression is the most common neuropsychiatric disturbance in Parkinson’s disease affecting about 40% of the patients. It is particularly crucial as it is associated with a higher rate of progression of the symptoms, greater decline in the cognitive skills, leading to a poorer treatment compliance and quality of life and increase in the financial burden on the caregiver. It has also been researched that as compared to the motor disability in Parkinson’s patients, depression has been found to be a more sensitive predictor of the overall disability of the affected individual.

Poor sleep, decreased energy, lack of concentration and psychomotor retardation are seen in almost all the patients of Parkinson’s disease and the cluster of these symptoms are used to make the diagnosis of depression. The etiology of depression in Parkinson’s patients is multifactorial. While many patients are thought to be demoralized about suffering through the serious and progressive illness, on the other hand other factors have also been investigated which include the examination of  level of neurotransmitters levels in the cerebrospinal fluid,  neurological examination and neuroimaging techniques with PET scan. These diagnostic methodologies have come to the conclusion that the patients of Parkinson’s disease have depression because of the damage to the serotonergic system as well as to the dopaminergic basal ganglia-limbic-frontal system which are  predominantly involved in the mood regulation and in the feeling of pleasure and general well being.

The treatment for depression in Parkinson’s patients involve the use of nortriptyline and paroxetine antidepressants. It has also been established that the management of depression leads to a generalized improvement in the quality of life, sleep pattern and certain aspects of cognition in such patients. However the inter-individual differences in response to various medications and the patient’s tolerability must also be kept in mind. It has been scientifically studied that there is a slight worsening of the motor symptoms in Parkinson’s disease with the use of SSRIs antidepressant drugs. Also there has been a study to indicate a potentially serious interaction between the monoamine oxidase B inhibitors antiparkinsonian drugs with the antidepressant drugs. Having said that, it has been well concluded in various reports that the electroconvulsive therapy (ECT) is an effective treatment of the different patients in PD as in most of the cases it improves both the mood and the motor symptoms of the patients. Also, the patients must be encouraged to exercise, participate in local group discussions, and to keep up their social activities

Memory Loss in Parkinson’s Disease

Anything that affects cognition can affect memory too. However, sometimes it becomes difficult to differentiate memory loss or impairment due to PD from that due to normal aging process.

Subcortical cognitive deficits, as seen typically in PD patients, are characterized more by problems with memory recall (especially of recent events) than by memory formation, decrease in mental speed or slowed thinking (bradyphrenia), and apathy. It is not that PD patients suffering from bradyphrenia are unable to think. It is only that their thinking process is slow, so they need time to answer questions or make decisions.

Executive impairment may be more pronounced than language deficit. Executive functions involve higher level thinking skills such as logical thinking, prioritizing, organizing, planning, and executing. Dementia may be accompanied by psychosis, agitation, and sleep disturbances.

Personality Changes in Parkinson’s Disease

Personality changes occur frequently in people with PD. The caregivers of the Parkinson’s patients are frequently heard saying that “Parkinson’s has made their relatives different, that something has discernibly altered their loved ones.” Frontal cortical damage could account for some of the behavioral and personality changes that are seen in PD patients, such as depression, mental lethargy, mood swings, and irritability. On the other hand, obsessive compulsive behavior such as binge-eating, hypersexuality, and pathological gambling may be related to some drugs used to treat PD. The constellation of such traits are collectively called as Parkinson’s personality

A Parkinson’s personality is often mentioned in relation to PD patients. Certain personality traits have been noted in people with PD which includes being hard-working, ambitious, serious-minded, dogmatic and honest. They are less likely to have any addictions to alcohol, tobacco or drugs. These traits may be present even before the development of PD. One theory that may explain this is that loss of dopamine (which is thought to be responsible for these personality traits) starts long before the manifestation of motor symptoms.

It must be kept in mind that the Parkinson’s disease is the result of the deficient dopamine in the brain and it is not at all the fault of the patient that he/she is no longer the same individual as before the diagnosis of the disease. This fact is important to the families challenged by the Parkinson’s in regard to the financial and emotional stability of the caregiver. The biggest source of conflict in the families arises  when the caregivers are unfair to the person with the brain insult. It is important for the families to articulate their feelings that the person has now changed and that they must have strength in optimism, hope for the progress, and provide immense love and support to the affected individual.


  1. I cannot stop doing distracting stupid and prejudicial whishes of the moment.I take requip. It is because of Requip? Shall I stop it ?

      • My husband has Parkinson’s disease, and he also takes Requip. He has become addicted to gambling to the point where we do not go anymore. He would spend way too much money and would not listen to me. His neurologist told us that taking Requip had a lot to do with this behavior. He stated that Requip makes PD people have extreme highs.

  2. My wife was on Requip then Requip XL, was unbelievably compulsive on both even where the dose was reduced below 10mg the compulsive behaviour continued until the specialist removed requip and introduced Leva Dopa

  3. My grandma has been sufferring from PD for 30+ years, she is currently 82 years old and lives in a frail care unit. I wanted to ask you whether dimentia and aggression are particular symptoms of PD?
    The problem is, she has been in hospital a lot the past year and she claims the staff at the frail care abuses her, the problem is, we have heard a lot of stories about her:
    1) Apparently she refuses to eat at times
    2) She is very aggressive towards the staff
    3) Stuborness
    4) Apparently she has kicked and hit the staff
    5) Screams and Shouts

    The latest is; the staff claims she fell out of her bed and my grandma claims they hit her.

    The other problem is; the way people claim she is at the “Home” and the way she is infront of us is as if it is two TOTALLY different people????


  4. you have to listen to your grandmothers both were in a home at the same place.when we visited my one grandmom said she was not a diabetic anymore and there for she didnt get her insulin.we didnt really know what to think so i went to vistit my other grandma in the next hall.she cried and whispered they were hitting her and they werent giving her any insulin. she begged me to take her home.i asked the staff about this and they said the same thing.they were very violent and combative patients.i couldnt believe this cause my one grandma only had been there a i went home to think this through.3 days later i got a call my grandma was dead.then the following monday i get a call my other grandmom was this day i feel so guilty for not listening to them.i dont trust people who act like the elderly are bad.i think it shows a reflection on the nurses.would it hurt anything to have her home for a week with home care.and try to listen to your heart.hope the best for you….thelma

  5. hello
    my father is 81 and has been diagnosed with pd for 1 year. he just now is starting inappropriate behavior with the cleaning lady. he is making inappropriate remarks to her and just recently exposed himself to her. this is very upsetting for his family members. it is out of character for him. when we called his neurologist she said that it wasn’t his meds and that if it was his meds he would be doing it alot more. it is more compulsive behavior if the meds were causing this behavior. we do not know what to do. any help would be appreciated.

  6. @ Sone Janson – we have the same problem with my ex-husband. He behaves completely differently with friends than he does with immediate family. Its like he not only has PD but schizophrenia also together with OCD and Bi-polar. As his wife and mother of his only child, I do not recognise this man, he is no where close to the man I married and has not been for over 25 years BUT I have tried and tried to help, support and be there for him with very little thanks, respect or understanding for me and my needs and the pain that I have been suffering. PD, the meds, symptoms, medical personnel and the OCD’s that go with it destroy families and make you feel you are loosing your mind as a carer. I wish I knew how to lobby for the drug companies and medical profession to take responsibility for these vile and evil medications.

  7. My husband and I are now divorced. He was having an affair with a coworker. He also had been diagnosed with PD 5 years ago. His subsequent behavior is in direct conflict to who I kknew him to be for 40 years. Do you think there is some correlation to the PD?

  8. A retired nurse I now care for elderly people in their own homes 24/7
    My newest patient has PD. He was lovely the first 10 days but has now changed into a badtempered, rude, aggressive person.
    It is VERY difficult to care for someone who does not try to cooperate.
    His family believe that all previous carers were at fault.
    Carers are not angels but neither are they ALL liars.
    I will give up this position, I do not need the stress.

  9. My step dad of 25 years is 60 years old. He has always had the tremors, but it is getting worse. His mother has it as well. He has always been like a loyal puppy to my mother, but over the last couple years he has changed. He is cheating on her, hiding money in a separate account and being just plain hateful. She has been down for a couple years with back issues, but is getting better. She has NOT let herself go, and still tries to keep up with the household chores. He is a totally different person. I don’ want them to divorce but he keeps saying it. Is there anything that we can do to stop this crazy behavior? He’s in denial.

  10. I ‘have had Parkinson’s disease for 21 years and have reached the advanced level of the disease. Additionally I have also been
    diagnosed with Narcolepsy and often fall asleep at the “drop of a hat.” In March, 2017 I underwent surgery to implant a Duopa Levodopa pump in my stomach to pump additional levadopa into my brain. Regrettably I went .through 7 different pumps.each of
    which failed in short order. Thus, I have had no consistent medications for my disease for more than 5 months and my tremors have increased to the point that I now have severe “meltdowns” every” day. These cause me significant discomfort and make significant daily work nearly impossible to accomplish. I can no longer walk and all of my work is accomplished from my wheelchair. I have faithfully done stretching exercises and stretching routines but they have not added much to my life. I have thought about deep brain surgery but feel that this may be denied me because I am 81 years old.

    I would be.
    I would be grateful for any suggestions any one could send my way.

    I taught in colleges and universities for 44 years was an organist and choirmaster for 50 years and taught piano lessons and music history classes for 44 years..

    Thankful very much.


    Clayton W. Henderson
    Professor of Music Emeritus of Music
    Saint Mary”s College
    Notre Dame, Indiana . 46635

  11. My husband of 25 years has been taking Requip for years, and a very high dosage. He became a sex addict, hiding porn, lying about it and breaking promises over and over. A few months ago, he graduated to the real thing…prostitutes, and over two dozen of them in a four month period. I found out and all hell broke loose, ending with me tearing my ACL and more…Parkinson’s has pretty much ruined my life and our marriage. I find myself wishing one of us were dead and just waiting to see what happens when he gets worse and worse. He has stopped taking the Requip, but his moral compass is gone and not coming back, since he still doesn’t think engaging prostitutes is wrong. He and his brain have been destroyed by this disease. I resent it and I resent him and I don’t know how to forgive him. Therapy is okay, but it won’t undo what has been done.

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