A 70-year-old man is brought to the emergency department after falling and breaking his hip. When questioned further, it becomes apparent that he is confused, has trouble maintaining attention and easily distracted and disinterested. However, when asked about his childhood memories, he is able to recall vivid details about his early life. His wife mentions that he tends to hallucinate and become restless quite often. On Mini-Mental State Examination, he scores 21 and exhibits bradykinesia, a shuffling gait, and a tremor in his left hand.

What is the most likely diagnosis?

Options:
explanation: Alzheimer's dementia is characterised by a gradual onset (over several years) of memory impairment, which is followed by difficulties in language and executive function. The patient's history of recurrent visual hallucinations and sleep disturbances are not typical features of Alzheimer's dementia. It should be suspected in adults who demonstrate long-lasting problems with spatial navigation and visual awareness, and usually manifests as wandering or becoming lost.
name: Alzheimer's dementia
label: c
answer: no
explanation: Multiple sclerosis (MS) is a chronic autoimmune disorder that affects the brain, spinal cord, and optic nerves. MS is more common in females under the age of 50 years, often presents as muscle (sensory) weakness, spasticity, loss of balance, and visual disturbances. The patient's wife mentions that he tends to hallucinate and become restless quite often, which are not typical symptoms of MS.
name: Multiple sclerosis
label: e
answer: no
explanation: Vascular dementia usually presents in patients with history of multiple cerebrovascular events, either transient ischaemic attacks or strokes. Typically there is a step-wise deterioration of cerebral function with each event. It should be considered in those with a history of cerebrovascular disease with global impairment of cognition.
name: Vascular dementia
label: b
answer: no
explanation: Pseudo-dementia is a functional psychiatric illness (or rarely a deliberate simulation) that can mimic the apparent cognitive decline of true dementia. It is believed that pseudo-dementia is triggered by intense stress and head injuries, and linked to depression. It will characteristically ameliorate once the depression has been treated.
name: Pseudo-dementia
label: d
answer: no
explanation: The most likely diagnosis in this scenario is Lewy-body dementia (LBD). It is a progressive degenerative dementia that is characterised by a decline in cognitive function, and symptoms such as visual hallucinations, sleep disturbances, and behavioural changes. The patient has difficulty maintaining attention and is easily distracted and disinterested, however, he is able to recall vivid details about his early life. This is an example of **fluctuating cognitive function** which is a common feature of LBD. Additionally, his examination findings (features of parkinsonism) further supports the diagnosis. Lewy-body dementia is characterised by the presence of Lewy bodies in the brainstem and cortex with a myriad of features of dementia and Parkinsonism.
name: Lewy-body dementia
label: a
answer: yes

Correct answer: a