The impact of non-adherence to therapies for neurological disorders: higher costs and worse outcomes

  • Medication non-adherence is pervasive and costly, with annual cost estimates totaling $290 billion and €1.25 billion in the US and Europe.
  • Neurological disorders have significant associated costs and are likely to reduce quality of life of patients. Improvements in adherence could improve symptom management and reduce costs. 

Increasing adherence to therapy represents a significant opportunity area for improving outcomes.

Increased adherence can improve the clinical outcomes and quality of life of patients with neurological disorders.1,2 Patients with Parkinson’s disease have higher medical-care needs, often miss work and require care; these effects contribute to the overall economic burden.3 Patients with uncontrolled epileptic seizures can experience severe physical injuries such as head trauma and fractures, but also psychosocial problems such as depression and anxiety.2

Despite this, adherence levels are not always high. In Parkinson’s disease, reported non- adherence rates are reported to vary between 10 and 67%,4 and may reach 50% for other neurological conditions such as epilepsy and bipolar disorder.2,5

Non-adherence is a global issue driving negative outcomes and increased costs.

Non-adherence to therapies, particularly medication, is associated with various negative outcomes; studies in the US indicate that medication non-adherence is the cause of 10% of hospitalizations and 23% of nursing-home admissions in older adults, with the typical non- adherent patient requiring three extra medical visits per year and generating an additional $2 000 in treatment costs per annum.6,7 The magnitude of costs associated with non- adherence is staggering: annual cost estimates for the US and Europe total $290 billion and €1.25 billion, respectively.7 In the UK, non-adherence is believed to cost the NHS more than £500 million per year.8 Specific information on non- adherence in developing countries is not available; however, given that secondary prevention medicines are often difficult to access and afford in many of these countries, non-adherence trends, and thus, healthcare utilization and cost, can reasonably be expected to be worse.9

Improving adherence to treatment could reduce the burden for patients, healthcare providers and society.

Non-adherence in neurological disorders depends on many factors, including both clinical and demographic factors, as well as affordable access to medications.10,11 Poor adherence to epilepsy medication can increase overall medical costs, as a result of increased emergency department attendances and inpatient admissions,12 and non-adherence was associated with an over threefold risk of mortality compared with adherence in a U.S. study of over 33,000 patients.13 An analysis of U.S. managed care plans found that patients who were non- adherent to Parkinson’s disease medication had significantly higher rates of yearly hospitalizations (2.3 vs 1.8).14

Since adherence is key to achieving symptom control, interventions aimed at enhancing adherence behavior, such as simplifying dosage regimens, patient education and behavioral interventions, have the potential to reduce the burden on patients and healthcare services.10


…non-adherence is the cause of 10% of hospitalizations and 23% of nursing home admissions in older adults, with the typical non-adherent patient requiring three extra medical visits per year and generating an additional $2 000 in treatment costs per annum.6,7

Addressing the indirect costs of neurological disorders is a significant opportunity area.

Patients with neurological disorders also experience indirect costs of their condition. Patients with Parkinson’s disease have higher medical-care needs, often lose the ability to work and require assistance from paid and unpaid carers.3 It has been reported that family carers (particularly spouses) spend an average of 22 hours per week providing care; the direct and indirect burdens are likely to be substantial.3

Improving adherence trends requires a comprehensive understanding of its drivers

Initiatives to improve adherence must be rooted in a comprehensive understanding of the different adherence factors and their respective drivers. Physicians have a key role to play in affecting patient adherence – both to medication and to lifestyle recommendations. In future articles we will examine in detail exactly what those behavioral drivers are and provide tools to healthcare professionals to help them “nudge” patient behavior towards adherence. Just as physicians must make the proper clinical diagnosis and treatment decision, they can have a considerable impact on outcomes by making the right behavioral diagnosis and treatment choices. This will be the objective of future articles.


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  2. Ferrari CMM, et al. Factors associated with treatment non-adherence in patients with epilepsy in Brazil. Seizure 2013;22:384–9.
  3. Yang W, et al. Current and projected future economic burden of Parkinson’s disease in the U.S. Nature Partner Journals Parkinson’s Dis 2020;6:15.
  4. Straka I, et al. Adherence to Pharmacotherapy in Patients With Parkinson’s Disease Taking Three and More Daily Doses of Medication. Frontiers in Neurology 2019;10:799.
  5. Jawad I, et al. Medication nonadherence in bipolar disorder: a narrative review. Ther Adv Psychopharmacol 2018;8(12):349–63.
  6. Lynch SS. Adherence to Drug Treatment. MSD Manual. Available at: drugs/adherence-to-drug-treatment [Accessed March 2021].
  7. Cutler RL, et al. Economic impact of medication non-adherence by disease groups: a systematic review. BMJ Open 2018;8:e016982.
  8. Taylor L (PharmaTimes Online). Drug non-adherence “costing NHS £500M+ a year”. Available at: adherence_costing_nhs_500m_a_year_1004468 [Accessed March 2021].
  9. World Health Organization. Adherence to Long-Term Therapies: Evidence for Action. 2003. Available at: [Accessed March 2021].
  10. Daley DJ, et al. Interventions for improving medication adherence in patients with idiopathic Parkinson’s disease. Cochrane Database of Systematic Reviews 2014: Issue 8.
  11. Moura LMVR, et al. Patient-reported financial barriers to adherence to treatment in neurology. ClinicoEconomics and Outcomes Research 2016;8:685–94.
  12. O’Rourke G and O’Brien JJ. Identifying the barriers to antiepileptic drug adherence among adults with epilepsy. Seizure 2017;45:160–8.
  13. Faught E, et al. Nonadherence to antiepileptic drugs and increased mortality: findings from the RANSOM Study. Neurology 2008;71(20):1572–8.
  14. Fleischer JE and Stern MB. Medication Non-adherence in Parkinson‘s Disease. Curr Nerol Neurosci Rep 2013;13(10):10.1007/s11910-013-0382-z.