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Summary Capita selecta - medical psychology
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Extensive summary of the capita selecta/selected topics - medical psychology course. Contains a summary of all the book chapters and articles.
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Capita Selecta – MedicalNeuropsychology
Handbook of medical neuropsychology
3 Neuropsychological problems in neuro-oncology
Introduction and history
Neuropsychological studies in the field of oncology are often related to neuro-oncology: (1) brain
tumors – which arise from neurons and other brain tissues, cranial nerves, leptomeninges,
neuroendocrine glands, skull, and blood vessels, and (2) treatment effects. The neurocognitive effects
of brain tumors themselves are variable and require close examination of the neurocognitive
underpinnings of composite test scores.
Brain tumors and cancers that metastasize to the brain allow cancerous cells to pervade normal tissue
and to exist in areas where healthy neural tissue can still function. Furthermore, brain tumors are not
fully visualized on brain scans. Also, how do surgery, chemotherapy and radiotherapy affect the
brain?
Diagnosis of brain neoplasms
Risks for developing a brain tumor
The onset of the tumor cannot be estimated for most tumor types. Risk factors include serious head
injuries decades before the tumor is diagnosed (meningioma), prior radiation exposure decades
before, immune suppression leading to lymphomas, and genetic disorders.
Brain tumor classification and histologic groupings
Tumors are defined by the cells from which they were generated in their uncontrolled genetic forms.
Tumor grading
The current method for tumor grading is a four-level system derived by the American Joint
Commission on Cancer and previously was based on a 3-level system by the WHO. The system of
grading generally determines the degree of malignancy of a tumor and classifies cells in terms of
abnormal characteristics, which informs the prognosis and treatment options. A general classification
of brain tumors is: (1) well differentiated and low grade; (2) moderately differentiated and
intermediate; (3) poorly differentiated and high grade; (4) undifferentiated and high grade. The tumor
grading criteria are specific for different tumor types. Below classification for gliomas:
● Low grade/I: tumor cells remain well differentiated without other signs of abnormality in cell
nuclei or tissue structure. Tumor cells grow slowly, rarely grow into surrounding tissue, and
may be gross totally resected.
● Low grade/II: moderately differentiated but still benign. Greater chance of de-differentiation
and transformation into a more malignant tumor and may have spread into surrounding
tissue.
● Anaplastic/III: tumor cells are poorly differentiated, the tumor has likely spread into
surrounding tissue, and the tumor is malignant.
● High grade/IV: undifferentiated and highly malignant and aggressive (e.g. glioblastoma).
,Neuropsychological mechanisms
The cognitive effects of brain tumors of similar histology and location are known to be highly variable.
There is evidence that functional brain tissue remains intermingled with tumor tissue, and this
conveys with its unpredictability in knowing the nature of neurocognitive impairment caused by a
tumor in a specific location in any one individual. Tumor grade is associated with the severity of
neuropsychological deficit (high grade tumors grow quickly and may invade the contralateral
hemisphere, and thus are more disruptive of neural connections).
Effects of tumors on cognitive function
the theory of how brain tumors cause functional damage has traditionally been based on the
observation that brain tumors are associated with less functional damage than other more rapidly
acquired brain injuries such as head injuries and stroke. Case studies show that the change in
function can be major; tumors can masquerade as dementia and as psychiatric syndromes. Brain
tumors damage normal tissue by compression and infiltration. A study found some functional tissue
in the tumors of all patients. Tumors seem to result in less injury than expected based solely on their
dramatic presentation on brain scan images.
The relative cognitive damage caused by brain tumors and strokes (comparing them) was investigated
by Anderson et al. The outcomes of the study emphasize the unpredictable nature of tumor effects
on cognition as well as sensorimotor function.
Tumors can infiltrate but not destroy tissue (until tumors become massive or bilateral), allowing some
neural function, and standard MRIs cans do not reveal the degree of necrosis and hypoxia within the
tumor that marks the more malignant and treatment-resistant lesion. PET scans are used to measure
tumor hypoxia. Injury is manifestly from tumor mass effects and vasogenic edema or the related
problems of hydrocephalus, ischemia, encephalomalacia and seizures.
Do tumors cause regional cognitive effects?
Studies have been consistent only in broad generalizations about structure-function; verbal functions
are associated with left hemisphere tumor lesions ad visuospatial functions with right hemisphere
lesions. Study: both left and right hemisphere patients produced fewer phonemic fluency responses
than the control group, but there was no significant difference between left and right frontal groups.
Semantic fluency was significantly inferior in the left hemisphere group.
Words vs. picture recognition: there was no effect of laterality of hemispheres on the hit rates
(accuracy) or recognition.
Attention (frontal lobes): deep tumor patients tended to have the lowest scores among the left and
right hemisphere and normal control groups.
Conclusions
Our studies all focused on patients without the confounding effects of radiation therapy and
chemotherapy, to which cognitive impairments from brain tumors have often been attributed.
Measures of reaction time in neurocognitive tests are often more sensitive to the effects of brain
tumors than accuracy rates. Tests of resource-limited cognitive functions are more sensitive to tumor
disruptions of neural networks. Statistically significant effects are not always found in brain tumor
studies, and regional patterns tend to be more qualitative, reflecting the variability among the
subjects presumably because tumor effects on cognition are less severe.
,Regional effects in individuals
The slow growth of many tumors, which moderates the interference with cognitive dysfunction, may
also be followed by reduced cognitive recovery. In contrast, the relative stability of cognitive function
in the presence of a stable tumor can be dramatically disturbed following resection.
Individualized approach to neuropsychological evaluation and case examples
The diffuse nature of even solid mass tumors requires a more individualized approach to
interpretation of neurocognitive evaluation, as typical syndromes and agnosias may not be seen.
However, consistent neuropsychological batteries should be used with greater emphasis on
component neuropsychological functions, rather than composite measures (e.g. IQ). Diagnosis of
neurocognitive impairment in patients with brain tumors focuses on the inconsistencies and
consistencies with the examiner’s expectation of the function associated with the tumor region and is
a useful teaching technique in understanding systems of brain associated with cognition.
Patients with thalamic tumors have selective difficulty with multi-tasking and other aspects of
attention. frontal lobe tumors will almost invariably cause memory impairment in the encoding
and/or retrieval and recognition of material requiring association. these are cases of low-grade
tumors. Is there a difference with high-grade tumors, since the traditional view is that tumors of
greater malignancy cause greater cognitive impairment? A study found that after the tumor was
resected, there was no basis for a malignancy effect in a large group of screened adults with unilateral
intracerebral gliomas.
Sensitivity of neuropsychological evaluation
The more individualized approach can be quite sensitive, as demonstrated by studies that compared
sensitivity of neuropsychological tests vs. MRI to detect tumor recurrence. The most predictive
measures of tumor recurrence were two indices of memory (recall and recognition of a word list),
which positively correlated with longer survival. The glioblastoma patients had a statistical tendency
to achieve poor maintenance of cognitive set (poor performance on Trail Making Test). Another study
showed that a patient-specific model was superior to a brief but generally sensitive model in
predicting tumor growth prior to clinically scheduled MRI scans. Findings suggest that a subject-
specific model can predict recurrence and may be more sensitive than general testing batteries. This
technique is suitable to a disorder that is associated with highly variable cognitive impairments
because it increases the specificity to the disease mechanisms.
Effects of neurosurgery on cognitive function
Tumor effects on sensation, motor function, and cognition can be exacerbated following surgical
resection, and new impairments can emerge. Sometimes resection causes an improvement in
cognition, personality, or mood, depending on tumor location, putatively related to alleviation of
mass effects. After surgery, cognitive function takes at least 2 years for recovery.
Syndromal neuropsychiatric disturbances and treatments associated with brain
tumors
Depression and fatigue
people who have newly diagnosed brain tumors report relatively low levels of depression that are not
consistent with the estimates in general oncology population. Brain tumors may produce less stress
than other cancers because the treatment period for brain tumors is shorter than for other common
cancers.
A study of the clinical predictors of poor quality of life for adult patients with brain tumors pointed to
being female, being divorced, having bilateral tumor involvement, having received chemotherapy,
, and having a poor performance status. Study: depression levels became clinically elevated 4-6 years
after diagnosis and were unrelated to stable fatigue levels. Brain tumors in the frontal lobes have the
highest regional association with depression an can be mistaken for a neuropsychiatric syndrome
such as depression. SSRIs are the medication of choice to treat adults and children with tumor and
treatment-related depression and anxiety. Methylphenidate is frequently used in the clinical
management of adults with depression and cognitive impairment and in children with learning
impairments, even though the most supportive evidence appears based on adult subjective
observations. Modafinil is being evaluated for its effectiveness in treating fatigue and cognitive
impairment in patients with cancer.
Anxiety
Anxiety is also a frequent psychiatric disorder associated with cancer. Study: MRI studies showed that
all the anxious patients had tumors either in the right cortex, often temporal lobe, or in the left
cerebellar hemisphere. In fact, 80% of the patients with tumors in the right cortex or left cerebellum
reported elevated anxiety symptoms.
Asperger’s syndrome/mild autism
children with brain tumors sometimes present with a pre-existing diagnosis of ASD, typically
Asperger’s syndrome. Clinical observations suggest that children with those behaviors, that is, with
(1) abnormalities in social cognition or social behaviors, (2) distress when environmental structure or
schedule is altered, (3) hyperfocus on limited personal interests, (4) stereotypical body or speech
expressions, often have lesions in the cerebellar hemispheres and/or the temporal lobes. It should be
noted that the terms are used descriptively and that the full syndrome may not be present.
Cognitive affective syndrome
the cognitive affective syndrome, defined by significant deficits in executive function, spatial
language, language, abstract reasoning, attentional regulation, memory and personality
(hyperactivity, impulsivity, etc.) is associated with bilateral or large unilateral lesions in the posterior
cerebellar lobes, vermis, and in pan cerebellar disorders. The co-occurrence of the cognitive and
affective symptoms is thought to arise from the disruption of the cerebello-thalamo-cortical and
cortical-pontine-cerebellar tracts connecting the cerebellum with frontal, parietal, temporal and
limbic cortices.
Obsessive-compulsive disorder
Study found higher ratings of obsessionality 3 months after surgery in frontal locations and women.
OCD resulting from a brain tumor, resection, and/or resulting encephalomalacia affecting the frontal
lobes may have atypical characteristics that can make the OCD difficult to treat. Normally, treatment
depends on identifying the sources of anxiety. However, with tumors, the etiology is neurological and
thus less amenable to change.
Hypothalamic syndromes
Tumors originating in the hypothalamus are, first, associated with disorders of eating behavior.
However, they produce other symptoms that lead to changes in growth rate and to hyperactivity,
irritability, attacks of anxiety, euphoria, aggressiveness, disruptions of vision, sleep disturbance, and
headaches. Also seizure disorders are associated.
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