Brain Recovery: Teen Stroke And Intelligence

Intelligence recovery after a stroke is a complex process that can vary widely depending on the individual and the nature of the stroke. While physical effects such as hemiparesis or aphasia may be more immediately apparent, cognitive changes can also significantly impact a survivor's daily life and ability to function. Cognitive impairment after a stroke can affect various domains, including memory, attention, language, perceptual-motor skills, and executive function. The left frontotemporal lobes, left thalamus, and right parietal lobe are areas of the brain highly involved in cognitive functions, and damage to these regions is most likely to result in post-stroke cognitive impairment.

The recovery process and prognosis for cognitive impairment after a stroke are highly variable. While some individuals may recover fully, others may experience persistent deficits or gradual decline. The first few months after a stroke are critical for cognitive recovery due to heightened neuroplasticity, which allows the brain to adaptively rewire itself and restore lost functions. Early cognitive screening, rehabilitation, and pharmacological interventions can play a crucial role in promoting optimal recovery.

Various strategies can be employed to enhance cognitive recovery, including cognitive rehabilitation exercises, physical exercise, pharmacological treatments, and emerging approaches such as growth hormone therapy, non-invasive brain stimulation, and acupuncture. Additionally, technological advancements have led to the development of digital tools and applications that can supplement conventional rehabilitation methods and provide a gamified, engaging approach to cognitive recovery.

The impact of stroke on intelligence and the potential for recovery are multifaceted and depend on a range of factors. Further research and understanding are needed to optimize rehabilitation strategies and improve long-term outcomes for individuals experiencing post-stroke cognitive impairment.

The impact of early-life intelligence quotient on post-stroke cognitive impairment

Cognitive impairment is a common complication of minor strokes, but there is limited information on risk factors, including peak cognitive ability earlier in life. This study aimed to investigate the impact of early-life intelligence quotient on post-stroke cognitive impairment and to determine the role of pre-morbid intelligence quotient in predicting cognition after a stroke.

Methods

The study recruited 157 patients with clinically evident lacunar or minor non-lacunar ischemic stroke. Clinical features, vascular risk factors, stroke subtype, and small vessel disease burden were recorded. Educational attainment, current cognition, pre-morbid intelligence, and dependency were assessed at 1-3 and 12 months after the stroke.

Results

The results showed that 23% of patients had a cognitive impairment score below the threshold at 1-3 months, and 19% had a similar score at one year. Lower pre-morbid intelligence scores and older age were found to be significant predictors of one-year cognitive impairment, more so than stroke severity or vascular risk factors. Additionally, cognitive impairment was associated with a higher number of white matter hyperintensities.

The study provides evidence that pre-morbid intelligence quotient and education level predict cognition after a stroke. It also confirms the association between cognitive impairment and small vessel disease. The findings suggest that pre-morbid intelligence should be considered in future studies of post-stroke cognition to better understand and manage cognitive impairments following strokes.

Factors causing residual syndromes after stroke

The factors that cause residual syndromes after a stroke can be categorised into two groups: those that are influenced by the location and extent of the brain damage, and those that are influenced by patient variables.

Factors influenced by the location and extent of brain damage

• Location of the stroke in the brain: A stroke on the left side of the brain will affect the right side of the body, and vice versa. A stroke towards the back of the brain will likely result in some disability involving vision.
• Extent of brain damage: The more severe the stroke, the more likely the patient will experience permanent disability.

Factors influenced by patient variables

• Age: Older patients are more likely to experience cognitive impairment after a stroke.
• Education: Higher levels of education are associated with better recovery from cognitive sequelae of stroke.
• Antidepressant use: The use of antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), may have a positive effect on stroke recovery.
• Time since stroke: The single most important determinant of recovery of speech production is time since the onset of stroke, indicating that improvement continues over time, even in the chronic stage.
• Initial severity of stroke: The degree of recovery from neglect is associated with lower initial severity of the specific type of neglect.

Cognitive rehabilitation

Attention

Memory

Memory is the ability to encode, store and retrieve information. Memory problems are a common cognitive complaint following stroke. Memory rehabilitation programmes either attempt to retrain impaired memory functions, or teach patients strategies to cope with them. Factors that can contribute to memory difficulties include attention and executive function. In addition, the presence of low mood and/or apathy also needs to be assessed as both of these are associated with stroke and can present with memory problems.

Executive Functioning

Executive functioning skills are often required for successful carryover of memory and attention strategies, however, can also be at risk for impairment in the setting of stroke. If executive functioning impairments are severe, interventions may need to target increasing awareness of cognitive impairment and training of individual functional tasks with understanding that skill acquisition may not carry over to untrained tasks.

The impact of bilingualism on aphasia

Bilingualism has been shown to have a protective effect on aphasia. A study by De Letter et al. found that bilingual aphasic patients have a higher probability of improving their processing speed during rehabilitation, resulting in a shortening of the mismatch negativity (MMN) latency over time. This is in contrast to monolingual aphasic patients, who showed an increase in MMN latency at the second timepoint.

Another study by Ardila et al. found that bilingualism represents a protective factor in vascular aphasia, with aphasia being less severe in certain subgroups, such as those with higher lesion volume, male gender, and sub-cortical stroke.

A meta-analysis by Kuzmina et al. found that bilingual speakers with post-stroke aphasia showed better performance in their first-acquired language (L1) compared to their later-learned language (L2). This effect was moderated by age of language acquisition, with those who learned L2 before the age of seven showing comparable performance in both languages, and those who learned L2 after the age of seven showing better performance in L1.

Premorbid language proficiency and frequency of language use were also found to moderate the difference in performance between L1 and L2. Individuals with higher L1 proficiency and those with equal proficiency in both languages showed better performance in L1, while those with higher L2 proficiency performed better in L2. Additionally, individuals who premorbidly used L1 more frequently showed significantly better performance in L1 compared to L2.

Linguistic similarity between the languages spoken by the bilingual did not appear to influence the magnitude of the difference in performance between L1 and L2.

The role of neuroplasticity in cognitive recovery

The brain's ability to adapt and change is known as neuroplasticity, and it plays a crucial role in cognitive recovery after a stroke. Neuroplasticity can occur through local restitution, reorganization, and compensatory reassignment.

Neuroplasticity can be leveraged to aid in the recovery of cognitive functions such as memory, attention, and decision-making. It is important to note that the brain's propensity for neuroplasticity allows it to make new connections and reroute neuronal pathways to compensate for disturbances caused by brain injuries.

Several factors influence neuroplasticity, including cellular and molecular mechanisms, structural and functional changes, and environmental and genetic factors.

Techniques such as constraint-induced movement therapy, cognitive rehabilitation, virtual reality, and brain-computer interfaces can be used to harness the potential of neuroplasticity and enhance cognitive recovery.

Additionally, non-invasive and non-pharmacological lifestyle interventions, such as physical exercise, cognitive stimulation, socialization, a healthy diet, and caloric restriction, can promote neuroplasticity and improve cognitive function during aging.

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