Assessing and Treating Cognitive, Mood Impairments in Patients With Stroke

Every year, more than 795,000 people in the United States have a stroke, of which approximately 610,000 are first or new strokes.¹ While stroke can occur at any age, the risk of occurrence increases with age, doubling each decade after the age of 55; 75% of all strokes occur in people older than 65.² According to the Centers for Disease Control and Prevention 2017 stroke statistics, every 40 seconds someone in the United States will have a stroke, and someone will die from a stroke every 4 minutes.¹ Stroke is the fifth leading cause of death in the United States and is attributed to approximately 140,000 deaths each year.³

The impact of stroke can be devastating, with survivors experiencing physical disability manifesting in several domains including paralysis, problems with balance or coordination, and speech defect. Less obvious is the impact of stroke on cognition, memory, attention, and depression. 

Poststroke depression is common and prevalence rates between 5% and 64% have been reported,⁴ correlating positively with cognitive impairment, reduced functional outcome, compromised quality of life, and increased mortality.⁵ In patients with subacute and chronic stroke, neuropsychological assessments also show deficits in the executive functioning of the brain, including attention, mental processing speed, and visual perception.⁴ The risk of transitioning to dementia is 6-times higher in patients with moderate cognitive impairment following stroke compared with patients without cognitive impairment.⁶ An annual conversion to dementia has been reported in 8% to 13% of patients in the first year after a stroke,⁴ increasing to 30% with repeated stroke.^6,7

Increasingly recognized is the positive correlation between cognitive impairment and increased risk of poor functional outcome, long-term disability, and increased risk of death in patients following stroke.⁷ Although the relationship between cognitive impairment and depression is not well understood, it has been suggested that stroke patients who co-present with executive dysfunction and late-onset depression that manifest after 60 years of age have a worse outcome. This co-presentation — referred to as depression-executive dysfunction syndrome (DES) — has been shown to be associated with worse prognosis and longer recovery compared with either executive dysfunction or post-stroke depression presenting in patients following stroke.⁵

Rehabilitation of patients following stroke is important for regaining functionality. In most cases, however, rehabilitation focuses on addressing the physical and communication deficits frequently resulting from stroke, with significant improvement.^6,8 While cognitive and emotional deficits are known to be evident poststroke, the true impact of these deficits on the patient is unknown; therefore, rehabilitation of cognitive and mood impairment following stroke has received less attention.  Yet, physicians are tasked with providing care for stroke patients and must assess the physical as well as the cognitive and mood deficits in order to determine optimal treatment and support.

Currently, there is no established evidence-based treatment aimed at improving cognitive function after a stroke.  The efficacy of the psychological interventions currently used has not been established, and the true impact of DES is poorly understood,. Studies focused on assessing the effectiveness of post-stroke cognitive rehabilitation interventions are limited, and among the available studies, the overall findings are inconclusive.⁶

A key challenge to cognitive and mood rehabilitation is the lack of a clear definition of cognition, the subjective nature of the assessments, and a wide variation in the assessment tools and their appropriateness for the assessment of cognitive, mood, and anxiety domains. Indeed, assessment tools are often selected based on an individual clinician’s preference, potentially influenced by the time frame for the assessment and the health care system. To assess cognitive challenges, some of these tools are used retrospectively, often in the format of a questionnaire usually completed by the spouse or relative of the stroke patient. Clearly, there is a difference between a self-reported symptom such as depression and a diagnosis determined by clinical assessment, as the former cannot provide a comparative picture of the pre-stroke cognitive state.⁷ In fact, the appropriateness of neuropsychological assessment tools such as the Mini-Mental State Examination and the Montreal Cognitive Assessment has been called into question as some are unsuitable for identifying specific cognitive deficits among patients experiencing subacute or chronic stroke.⁴ In their study examining an association between neuropsychological measure, symptoms of depression, and self-reported cognitive dysfunction, Nakling and colleagues used both the Hospital Anxiety and Depression Scale and the Memory and Thinking Scale associated with the Stroke Impact Scale to evaluate various cognitive domains including cognitive abilities, visual and verbal memory, mental processing speed, executive functioning, and language production. Their study found low sensitivity and specificity for the Memory and Thinking subscale from the Stroke Impact Scale.⁴ 

Variations in the sensitivity and specificity of the various assessment tools and, in some cases, their inappropriate use for assessing cognitive and mood decline after a stroke challenges the early and accurate identification of cognitive and mood problems. Progress is, however, being made. Evidence-based psychological interventions to improve cognitive function after a stroke are being investigated.⁶ Based on the current evidence, the recommendation is for a more comprehensive neuropsychological assessment that goes beyond screening for the cognitive deficit, and with long-term monitoring of stroke patients, including informing the patient that cognitive symptoms may manifest even if they are not evident immediately following the stroke. Consequently, neuropsychological assessments are increasingly transitioning from a subjective to an evidence-based standardized stroke assessment that includes assessing cognition and mood in the pre-stroke state, screening for delirium, and integrating cognitive and mood testing with an assessment of function. Physicians will therefore be required to select the screening tool that is appropriate to the domain being tested and to defer a diagnosis of dementia for at least 6 months after the stroke event.⁷ The ultimate goal is to enable physicians to make decisions for initiation of treatment and rehabilitation that is individualized and appropriate to the patient’s needs, thereby improving patient outcomes.

References

1. Benjamin EJ, Blaha MJ, Chiuve SE, et al; on behalf of the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics—2017 update: a report from the American Heart Association. Circulation. 2017;135:e229-e445.
2. Ovbiagele B, Nguyen-Huynh MN. Stroke epidemiology: advancing our understanding of disease mechanism and therapy. Neurotherapeutics. 2011;8(3):319-329.
3. Yang Q, Tong X, Schieb L, et al. Vital signs: Recent trends in stroke death rates – United States, 2000-2015. Morb Mortal Weekly Rep. 2017;66.
4. Nakling AE, Aarsland D, Næss H, et al. Cognitive deficits in chronic stroke patients: neuropsychological assessment, depression, and self-reports. Dement Geriatr Cogn Dis Extra. 2017;7(2):283-296.
5. Douven E, Aalten P, Staals J, et al. Co-occurrence of depressive symptoms and executive dysfunction after stroke: associations with brain pathology and prognosis. J Neurol Neurosurg Psychiatry. 2018: jnnp-2017-317548.
6. Merriman NA, Sexton E, Donnelly NA, et al. Managing cognitive impairment following stroke: protocol for a systematic review of non-randomised controlled studies of psychological interventions. BMJ Open. 2018;8(1):e019001.
7. Quinn TJ, Elliott E, Langhorne P. Cognitive and mood assessment tools for use in stroke. Stroke. 2018;49(2):483-490.
8. Mayo Clinic. Stroke rehabilitation: what to expect as you recover. Published online May 24, 2017. Available at:  https://www.mayoclinic.org/diseases-conditions/stroke/in-depth/stroke-rehabilitation/art-20045172. Accessed March 20, 2018.