Dementia

Today we discussed dementia, paricularly with a rapidly progressive course

General classification of dementias:

1) Alzheimer's disease: 60-70%- hallmark is early loss of anterograde memory, with loss of functioning. Late loss of languange function.


2) Non-AD: 30-40%

Vascular- hx of CV risk factors, hx of overt stroke. Imaging shows stroke, leukoencephalopathy, ischemic or degenerative changes. Classically step-wise, with steps overnight.


With Parkinsonism:
- Dementia with Lewy bodies and Parkinson's dementia. Difference is whether parkinsonism was present first for over 1yr, which means PDD. DLB is characterized by nonbizarre delusions, neuroleptic sensitivity, REM sleep behaviour disorder (i.e. no paralysis in sleep, acting out violent dreams), autonomic disturbance
- Progressive Supranuclear Palsy (PSP)- upward, then downward, then lateral gaze palsy. Prominent truncal parkinsonism, with severe postural instability. Very high fall risk. Increased tone. Minimal response to L-dopa.
- Cortico-basal degeneration (CBD)- marked laterality of movement disorder. Apraxia, alien limb possible. Minimal response to L-dopa


Frontotemporal dementia (FTD)
- Frontal: personality change, with executive dysfunction, disinhibition, and/or apathy
- Temporal: Memory loss in 25%, language deficits- all anomic, either fluent or non-fluent with circumlocution and word-finding difficulty.
NB- ALS may present this way


Rapidly progressive dementia- a long, but still incomplete list of potential causes

1) Atypical presentation of primary neurodegenerative dementias (FTD, AD, LBD, PSP, etc.)
2) Structural brain disease (tumors, bleeds, collections, NPH)
3) Medications- Li, serotonin syndrome
4) Seizures
5) Infections (HIV, PML, cryptococcal meningitis, syphillis, malaria, TB, bartonella, Whipple's)
6) Psychiatric illness
7) Prion disorder (CJD, vCJD)
8) Autoimmune (Hashimoto's encephalopathy, others)
9) Inflammation (MS, ADEM)
10) Paraneoplastic (limbic, brainstem, etc)
11) Vasculopathy (vasculitis, intravascular lymphoma, CADASIL)
12) Nutritional (B12, folate, niacin, thiamine)
13) Genetic- late presentation of genetic disorder (e.g. hereditary adrenoleukodystrophy, neuronal ceroid lipofuscinosis, etc.)
14) Toxin (cocaine, EtOH, amphetamines, heavy metals, solvents, chemotherapy)
15) Systemic disease (sarcoid, celiac, CNS lupus, Sjogren's, Behcet's)
16) Metabolic (hypothyroidism, hypercalcemia, etc.)

Investigations:

CBC, lytes, liver, renal, glucose, thyroid, B12. CT scan for subdural, NPH. Possible MRI with gadolinium, EEG.
In correct settings, consider HIV, syphillis, depression, CNS vasculitis (h/a, sz, dementia), prion disease

Links:

Click here for NEJM clinical conference on this topic
Click here for CMAJ review of dementia diagnosis