Diagnostic Approach for Dementia in Older Adults Over 65
In an older adult over 65 presenting with memory loss, confusion, and communication difficulties—especially with history of stroke, diabetes, or head trauma—you should immediately perform cognitive testing with the MoCA (not routine screening), obtain brain MRI to assess for vascular lesions and structural abnormalities, and order laboratory tests to exclude reversible causes before diagnosing dementia. 1
When to Test for Cognitive Impairment
Do not perform routine screening of asymptomatic individuals, as this lacks evidence and is not recommended. 1
However, you must actively evaluate when any of the following warning signs are present: 1
- Reported cognitive symptoms by patient or informant
- Unexplained decline in instrumental activities of daily living (managing medications, finances, appointments)
- Missed appointments or showing up at incorrect times
- Difficulty following instructions or taking medications correctly
- Decrease in self-care
- New onset behavioral changes including depression or anxiety in later life
High-risk patients requiring heightened vigilance include those with: 1
- History of stroke or TIA
- Late-onset depressive disorder
- Untreated sleep apnea
- Unstable metabolic conditions (diabetes) or cardiovascular disease
- Recent delirium episode
- First psychiatric episode at advanced age
- Recent head injury
- Parkinson's disease
Cognitive Assessment Tools
For rapid assessment (when time is limited), use: 1
- Mini-Cog
- Memory Impairment Screen (MIS) + Clock Drawing Test
- AD8
- Four-item MoCA (Clock-drawing, Tap-at-letter-A, Orientation, Delayed-recall)
- GP Assessment of Cognition (GPCOG)
For comprehensive assessment (preferred when time allows), use the Montreal Cognitive Assessment (MoCA), which is more sensitive than MMSE for detecting mild cognitive impairment, particularly when MMSE scores are in the "normal" range (24+). 1, 2 The MMSE remains widely used with high sensitivity for moderate dementia but lacks sensitivity for mild cognitive impairment. 1
Always obtain collateral history from a reliable informant using validated tools like the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) or AD8 to corroborate cognitive decline and assess functional impairment. 1, 2
Essential Neuroimaging
Anatomical neuroimaging is recommended in your patient given the following indications present: 1
- Recent and significant head trauma
- History of stroke (vascular risk factors)
- Diabetes (vascular risk factor)
- Gait disturbances (if present)
MRI is strongly preferred over CT, especially for detecting vascular lesions and dementia subtypes. 1 If MRI is performed, obtain these sequences: 1
- 3D T1 volumetric sequence with coronal reformations for hippocampal assessment
- Fluid-attenuated inversion recovery (FLAIR)
- T2 or susceptibility-weighted imaging (SWI)
- Diffusion-weighted imaging (DWI)
Use semi-quantitative scales for interpretation: 1
- Medial temporal lobe atrophy (MTA) scale
- Fazekas scale for white matter changes
- Global cortical atrophy (GCA) scale
If only CT is available, obtain non-contrast CT with coronal reformations to assess hippocampal atrophy. 1
Laboratory Workup to Exclude Reversible Causes
Order the following tests immediately to identify treatable conditions: 2, 3, 4
- Complete blood count with differential
- Comprehensive metabolic panel
- Thyroid function tests (TSH, free T4)
- Vitamin B12 level
- Methylmalonic acid and homocysteine (if B12 is borderline-low, these increase diagnostic sensitivity) 3
- Urinalysis with culture (to exclude infection/delirium)
- Hemoglobin A1c (given diabetes history)
Critical pitfall to avoid: Starting cholinesterase inhibitors without excluding reversible causes like B12 deficiency, hypothyroidism, and medication effects can lead to unnecessary treatment. 3
Assessment of Non-Cognitive Markers
Evaluate these additional risk markers: 1
- Gait speed: Test with stopwatch (cut-off <0.8 m/s coupled with cognitive impairment increases dementia risk) 1
- Parkinsonism: Increases dementia odds three-fold 1
- Frailty assessment: Marker of future dementia 1
- Neuropsychiatric symptoms: Use NPI-Q or Mild Behavioural Impairment Checklist (MBI-C) with informant input 1
- Sleep history: Including insomnia, daytime sleepiness, REM sleep behavior disorder 1
- Hearing impairment: Associated with dementia development 1
Behavioral and Functional Assessment
Assess behavioral symptoms using simple, validated tools: 1
- NPI-Q (brief Neuropsychiatric Inventory)
- Geriatric Depression Scale (GDS)
- Cornell Scale for Depression in Dementia
- Patient Health Questionnaire (PHQ-9)
Assess global function with caregiver input using: 1
- Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)
- HABC-Monitor
Assess caregiver burden using the Zarit Burden Interview, as this is a major determinant of hospitalization and nursing home placement. 1
Advanced Testing (When Diagnosis Remains Uncertain)
CSF analysis is not routine but can be considered in: 1
- Diagnostic uncertainty with early onset (<65 years)
- Predominance of language, visuospatial, dysexecutive, or behavioral features
FDG-PET scan should be obtained before DaTscan if the underlying pathological process remains unclear after baseline evaluation by a cognitive disorders specialist. 1
Special Considerations for Your Patient
Given the history of stroke, diabetes, and head trauma, this patient has multiple vascular risk factors requiring: 2, 4
- Systematic control of vascular risk factors (aggressive management of hypertension, diabetes, hyperlipidemia)
- Higher suspicion for vascular dementia or mixed dementia (Alzheimer's plus vascular pathology)
- More frequent follow-up (every 3-4 months rather than standard 6-12 months) if rapid decline is present 2, 4
If hallucinations or behavioral disturbances are prominent, strongly consider specialist evaluation for dementia with Lewy bodies, which requires fundamentally different management and has severe neuroleptic sensitivity with typical and atypical antipsychotics. 4