A 77-year-old woman dies of severe pneumonia with sepsis at a care home. She had poor episodic memory for recent events and deteriorating language functions for at least 2 years before her death.
The most likely pathology that could be seen in her brain tissue is:
B. The patient described in the question is most likely to have a diagnosis of Alzheimer’s dementia. Diffuse and neuritic plaques with amyloid deposits in cortex and hippocampus are highly suggestive of Alzheimer’s disease. Ballooning of cells with intraneuronal accumulations suggests Pick’s disease. Diffuse amyloid deposition restricted to blood vessels is seen in amyloid angiopathy. Eosinophilic rod-shaped inclusions of actin filaments are Hirano bodies, seen sometimes in Alzheimer’s disease.
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Which of the following receptors, on stimulation, reduces serotonin release?
A. 5-HT1B receptors are present as presynaptic autoreceptors. On stimulation, these receptors can decrease further serotonin release. Postsynaptic 5-HT1B receptors may have a role in locomotor activity and aggression. 5-HT1A receptors are associated with antidepressant activity. 5-HT2A receptors are implicated in hallucinogenic properties of LSD-like drugs and blockade is associated with antipsychotic activity. 5-HT3 is the only ligand-gated ion channel among serotonin receptors; it is present in gut in large numbers and may mediate emesis.
All of the following are true with respect to dopamine metabolism except:
B. Dopamine exerts its action via one of two families of dopamine receptors. After receptor stimulation, dopamine can either be taken back into the presynaptic neurone and destroyed or repackaged as a neurotransmitter. Among those dopamines that are taken back, some are metabolized by monoamine oxidase (MAO). MAOB selectively metabolizes dopamine. Catechol-O-methyltransferase (COMT) is localized in the postsynaptic neuronal cytoplasm and is involved in secondary metabolism of dopamine. The primary metabolite of dopamine is homovanillic acid (HVA).
Neuroendocrine abnormalities have been documented in depression and other psychiatric disorders.
Which of the following is not a neuroendocrine abnormality seen in depression?
B. In depression, hypercortisolism is seen in a subgroup of patients. This can be demonstrated by the dexamethasone suppression test wherein exogenously administered steroid dexamethasone fails to activate the negative feedback loop to reduce endogenous cortisol. Depressed patients also show blunted TSH response when thyrotrophin-releasing hormone (TRH) is injected. A brisk GH release seen on apomorphine/levodopa challenge is absent in some patients with depression. This suggests dopaminergic dysfunction in a subgroup. Clomipramine challenge in normal subjects leads to increased serotonergic activation and prolactin release. This prolactin response to clomipramine-mediated via serotonin is blunted in depression. Psychotic depression shows more HPA axis disturbance than non-psychotic depression. Melancholic (somatic syndrome) depression increases the chance of finding endocrine disturbances among depressed patients.
Event-related potentials (ERP) are records of the brain’s electrical activity in response to various stimuli. P300 is an extensively studied ERP in psychiatry.
Which of the following is true with respect to P300 abnormalities in schizophrenia?
D. P300 is a positive component that occurs 250–500 ms after stimulus onset. Amplitude and latency of P300 is altered in schizophrenia. These changes reflect a trait rather than being related to psychotic state, but these are not specific to schizophrenia; for instance Alzheimer’s disease patients show similar deficits. The reduction in amplitude is more pronounced in earlier-onset and paranoid subgroups. P300 is not affected by medication status, disease duration, or severity of psychopathology.
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