Neurosciences and Relevant Medical Knowledge: Structure, Function, and Mimics
Core concepts
Know the functional anatomy relevant to psychiatry: frontal lobe (executive function, personality), temporal lobe (memory, language, emotion), limbic system (fear, reward), basal ganglia (movement, reward circuitry), and the neurotransmitter systems (dopamine, serotonin, noradrenaline, GABA, glutamate). Understand the neurological mimics of psychiatric presentations: thyroid disease, B12 deficiency, syphilis, HIV, autoimmune encephalitis, and structural lesions. Recognise the signs of raised intracranial pressure, stroke, and seizure disorders.
Traps
Questions test whether a psychiatric presentation has an organic cause. Beware attributing a first episode of psychosis in an older adult, or a sudden personality change, to a primary psychiatric disorder without investigation. Know which tests are indicated and why.
Worked example
A 60-year-old presents with new-onset psychosis and cognitive decline. The rule of thumb: new-onset psychosis in later life warrants investigation for organic causes (imaging, bloods, infection screen) before a primary psychiatric diagnosis.
Key points for revision
Localise the lesion, then link it to the symptom.