Lecture 4: Neurocognitive Disorders

neurocognitive disorders

-decreased mental function due to a medical disease other than a psychiatric illness

-specific and permanent damage to neural basis gives rise to symptoms:

• disease

• trauma

• degeneration

-acquired deficit in cognitive function, not developmental → decline from a previous level of function

common causes of NCDs

• dementias → Alzheimer’s and Parkinson’s

• stroke

• traumatic brain injury

diagnostic class of NCDs

-previously referred to as delirium, dementia and amnestic and other cognitive disorders in DSM-IV

-in DSM-5 diagnostic category is now “neurocognitive disorders”

paradigm shift in diagnostic criteria

-easier to get a diagnosis

-allows for introduction of mild neurocognitive disorders into diagnostic criteria

-move towards thinking of NCDs as a spectrum

-memory impairment is no longer essential for a diagnosis

-impairment of one domain is now sufficient for a diagnosis

importance of paradigm shift

-life expectancy is increasing

-do not have screenings for dementia → limited reliable early biomarkers and idiopathic disease

-so need to identify disease early and find suitable treatment quickly → easier with broad diagnostic criteria

benefits of early diagnosis

-mild NCDs often progress to major NCDs → diagnosis allows for early intervention and monitoring of symptoms

-neuropathology underlying NCDs often emerges well before symptoms

-earlier interventions predict longer term efficacy

NCDs on the rise

-increases in acquired NCDs following neural insult

-medical advances mean there is increased survival for brain trauma

-understanding the effects of repeated minor brain injuries

-inflammation caused by covid may increase risk of dementia

NCDs and psychology

-result from neural insult or CNS dysfunction

-psychologists play a central role in:

• diagnosis

• assessment

• rehabilitation

• supporting caregiver

• research

cognitive impairments in NCDs

• memory

• attention m

• language

• visuospatial skill

• learning

• perception

• executive functions

-vital role of clinicians in assessing these abilities and interpreting deficits within the context of early stages

-often comorbid with other conditions

learning and memory deficits

-amnesia

• diminished ability to learn new information

• failure to recall past events

-specific traumatic head injury often results in anterograde amnesia

-results from damage to hippocampus or broader temporal lobe injury

attention and arousal deficits

-often earliest indications of onset

-lack of attention or increased distractibility

-diffuse neural basis → frontal and parietal regions implicated, but networks extend to subcortical structures

deficits in executive functions

• working memory

• problem solving

• goal directed behaviour

• attentional control

• inhibitory control

• planning and motor complex behaviour

• change in routine

-often expressed as poor judgement, inappropriate behaviour or erratic mood swings

language deficits - aphasia

-difficulty producing and/or comprehending speech

-very common

• Broca’s aphasia

• Wernicke’s aphasia

• conduction aphasia

Broca’s aphasia (language deficits)

-disruption of ability to produce speech

-comprehension is often maintained

-anomia → poor word retrieval

-agrammatism → difficulties with word ordering, selection and inflection

-articulation difficulties

-characterised by non-fluent speech

Wernicke’s aphasia (language deficits)

-deficits in understanding written and spoken language

-production often maintained

-anomia → poor word retrieval

-structurally intact speech rate

-content often meaningless

-unaware of impairment

-reading and writing impairments

visuo-perceptual functioning

-inability to process sensory information due to neural insult

-independent of memory loss → retain a memory of the objects, it is a visual perception deficit

agnosia (visuo-spatial functioning)

• prosopagnosia

• amusia

• akinetopsia

prosopagnosia (visuo-spatial functioning)

-face processing problems

-high incidence rate in right hemisphere stroke

-loss of familiarity of known faces

-will typically still show an understanding of the components of the face

akinetopsia (visuo-spatial functioning)

-loss of fluid motion perception

-vision becomes stroboscopic

-acuity for static objects preserved

motor deficits - apraxia

-loss of ability to execute learned movements

-may be able to perform a behaviour as part of a routine, but unable to on command

-typically caused by lesion or degeneration of posterior parietal lobe

domain specific apraxias

• limb apraxia → ability to perform gestures, interact with objects

• apraxia of speech → deficit in planning and sequencing the required movements to produce sounds in speech

specific causes of NCDs

• Alzheimer’s disease

• vascular NCDs

• Parkinson’s disease

• traumatic brain injury

• HIV infection

• prion disease

• Huntington’s disease

• frontotemporal NCD

identifying specific causes of NCDs

-often a difficult and lengthy process

-necessary to determine the nature of benefits and location of neural insults

-provide info about onset, type, severity, and progression of symptoms

-discriminate between neurological and psychiatric symptoms

difficulties with diagnosing NCDs

-symptoms and deficits in NCDs often closely resemble other disorders

-emergence of psychological problems during early stages of cognitive decline

-partially alleviated by brain imaging, but not fully → can lead to misdiagnoses

further difficulties with diagnosing NCDs

-considerable overlap in symptoms of different neurological disorders

-closed head trauma may produce memory deficits that resemble

-single factors may cause broad symptoms

major NCDs

-reflect substantial cognitive impairment

-correspond to disorders previously categorised as dementias

minor NCDs

-reflect more moderate impairments

-limited deterioration from previous level in at least one of the cognitive domains based on:

• concern there has been a limited decline in cognitive function

• deterioration does not interfere with self-reliance in everyday activities

major NCDs

-significant deterioration from previous level in at least one of the cognitive domains based on:

• concern there has been a significant decline in cognitive function

• a significant impairment in cognitive performance, preferably as documented by standard testing

• cognitive deterioration does interfere with self-reliance in everyday activities

deficits in major neurocognitive disorders

-language may become vague and empty → unable to name everyday objects

-apraxia and agnosia

-EFs functions are common → difficulty managing new tasks, recalling basic knowledge, difficulty counting or reciting alphabet

-poor judgement and risk taking

Weschler Adult Intelligence Scale-IV (NCD assessment)

-aggregate measure that can be used to provide scores on broad indices of ability

• verbal comprehension

• perceptual organisation

• working memory

• information processing speed

-provides info on source of deficits and developmental stage at which deficits emerged

-not always easy to apply

Montreal cognitive assessment (NCD assessment)

-high sensitivity tool used to diagnose mild NCDs

-useful for patients with early deficits

• trail making tasks → measures processing speed and integration of visuomotor functions

• clock drawing tasks → measures visual neglect

• simple word lists → measures comprehension and working memory

role of psychologist in rehabilitation

-help clients develop new skills/strategies to compensate for deficits

-therapy for comorbid disorders

-support comorbid disorders

-supporting clients to structure their living environment to accommodate changes in cognitive abilities

biological interventions in NCDs

-aim to stabilise or slow degenerative disorders

• pharmacological interventions

• deep brain stimulation

-can provide significant quality of life improvements

cognitive interventions in NCDs

-needed as biological treatments have limited long-term efficacy and have adverse side effects

-so, need to develop skills to overcome or adjust for cognitive deficits

-may employ compensatory strategies governed by undamaged systems

cognitive rehabilitation programmes

-flexible to nature and length of cognitive deficits

-gains in cognitive function over a range of domains

-often basic training procedures which train clients in the area of their deficit

-extended practice at task with feedback on performance or use of assistive technology/digital interventions

interventions for memory deficits

-full recovery of lost memory abilities often difficult

-focus of therapy is on compensatory strategies

-useful in prompting recall of known events, but still need other strategies

interventions for attentional deficits

-attention process training (APT)

-employs different strategies to promote and encourage attentional abilities

-supports improvements in attentional abilities and memory functioning

interventions for visuo-perceptual deficits

-limited cases of recovery from agnosia

-treatment often relies on compensatory strategies

interventions for apraxia

-deficits in planning and sequence of actions is assumed to be an impairment of gesture learning due to insult to motor memory systems

-gestural training is effective in rehabilitation

-contemporary research using virtual reality is promising

gestural training (interventions for apraxia)

-patients are required to:

• demonstrate use of a common object

• mimic an observed gesture

• distinguish between appropriate and inappropriate use of objects

-associated with significant reduction in errors during everyday tasks

interventions for language deficits

-for generic deficits, patients may undergo standard speech therapy

-assists with production and comprehension of speech

-often combined practitioner and home-based computer assisted therapy

constraint induced movement therapy (interventions for aphasia)

-patients often develop compensatory behaviours

-can improve communication, but may limit recovery of speech production

-CIMT → mass practice of verbal responses, when are unable to gesture - restrained them to make them practice verbal responses

-improves self, clinician and observer rating of communication ability

group communication treatment (interventions for aphasia)

-focusses on increasing communication and information exchange through any possible route

-goal directed → patients should have specific communication goals tailored to personally relevant situations

-not limited to speech

interventions for executive functions

-some overlap with interventions for memory and attention

-more specific interventions for problem solving, planning and goal directed behaviours

-often involve training in planning, goal-management and problem solving

visual imagery mnemonics (interventions for memory deficits)

-mnemonic imagery can lead to reliable memory improvement → associative imagery with memorable items

-efficacy depends on:

• severity of memory impairment

• patients’ motivation

-patients may need explicit prompting and support