What are the Co-Existing Conditions Affecting Thinking and Memory?

There are a number of other factors that can have a negative impact on a person’s cognitive skills, such as disorders of mood, anxiety and sleep. In some cases, these factors can make memory and thinking deficits worse as well as directly affect a person’s quality of life.


  • It has been reported that up to 50% of patients with PD may experience some form of depression, especially minor depression, during the course of their illness.
  • Depression is more likely to occur in cases of severe cognitive impairment.
  • The effects of depression on memory, attention and problem-solving skills have been well-studied in older people.
  • For example, depressed mood directly impacts attention, memory, mental calculations as well as problem-solving skills.
  • Successful treatment of depression with medication and psychotherapy can also improve these cognitive symptoms.

A combination of medications and behavioral strategies is usually the best treatment for cognitive problems in PD.


  • Anxiety may be as common as depression in PD.
  • While less studied, up to 40% of patients experience some form of anxiety.
  • Anxiety can interfere with memory storage, disrupt attention, and affect complex task performance.
  • For example, most people remember, “going blank” on a school exam when feeling anxious.
  • Many patients with cognitive difficulties will experience anticipatory anxiety in situations where they have to use their cognitive skills.
  • Similar to depression, successful treatment can lead to improvement of cognitive problems related to anxiety.

Sleep disturbance

  • The impact of poor sleep on attention, alertness and memory are well-known.
  • Studies of airplane pilots have shown that even mild reductions in sleep can directly impair a person’s attention, judgment and ability to multi-task.
  • Problems with falling sleep and staying asleep are very common in PD, especially as the disease progresses.
  • Four types of sleep problems have been reported in PD:
    1) Problems staying asleep and early morning awakening
    2) Involuntary movements and pain that interrupt sleep
    3) Increased nighttime urination
    4) Nighttime agitation, vivid dreams and visual misperceptions or hallucinations.
  • In such cases, a sleep study is important to examine the person’s sleeping patterns and how their sleep is disrupted.
  • Sleep problems are often addressed with medication and behavioral treatments, and as sleep improves, its impact on thinking and memory is reduced.


  • Just as fatigue can cause problems with movement and walking in PD, it can also impair thinking and memory.
  • For example, a patient with PD may have difficulty in performing a complex cognitive task, such as working on finances or taxes, over an extended period of time.
  • It is often better to divide these tasks into short 10—15 minute sections that are more manageable and maximize the person’s attention and energy resources.
  • Such a strategy will help minimize fatigue and keep the person on task.
  • It is also important to be aware that as the day wears on, the person with PD may begin to fatigue, both physically and cognitively. Therefore, it is better to do more complex tasks earlier in the day when the person feels “fresh.”
  • There are medications that are used to improve energy and alertness in PD (i.e. methylphenidate (Ritalin®) and modafinil (Provigil®), but many of these medications have yet to be studied extensively for this disorder.
  • Some medications used to treat PD have also been shown to have stimulating effects on thinking and energy levels (i.e. selegiline (Eldepryl®) and amantadine (Symmetrel®).

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Fatigue and Parkinson's Disease

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Mind, Mood and Memory

Medical content reviewed by: Nina Browner, MD—Medical Director of the NPF Center of Excellence at the University of North Carolina at Chapel Hill in North Carolina and by Fernando Pagan, MD—Medical Director of the NPF Center of Excellence at Georgetown University Hospital in Washington, D.C.

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