# Cognitive Impairment and Dementia Screening

## Introduction

Cognitive impairment ranges from **mild cognitive impairment (MCI)** to overt dementia and affects an estimated 10-15% of adults over age 65. Early detection enables advance care planning, medication optimization, safety interventions, and caregiver support. Internists play a central role in screening, initial workup, and ongoing management.

## Definitions and Classification

- **Mild Cognitive Impairment (MCI)**: objective cognitive decline without significant functional impairment; approximately 10-15% progress to dementia annually
- **Dementia**: acquired cognitive decline in one or more domains sufficient to impair **independent functioning**
- **Major subtypes**: Alzheimer disease (60-80%), vascular dementia (15-20%), Lewy body dementia, frontotemporal dementia
- **Delirium** must be distinguished from dementia; delirium is acute, fluctuating, and often reversible

## When to Screen

- **Medicare Annual Wellness Visit** includes a required cognitive assessment
- Screen when patient, family, or staff report memory concerns, confusion, or behavioral changes
- Assess cognition before major medical decisions or surgery in older adults
- Hospitalized patients with delirium should be reassessed for baseline cognitive impairment after resolution
- Routine screening in asymptomatic populations remains **controversial** (USPSTF: insufficient evidence)

## Screening and Assessment Tools

### Brief Screening Instruments

| Tool | Score Range | Abnormal Threshold | Time | Best Use |
|------|------------|-------------------|------|----------|
| Mini-Cog | 0-5 | ≤ 3 | 3 min | Rapid initial screening |
| MoCA | 0-30 | < 26 | 10 min | Sensitive for MCI |
| MMSE | 0-30 | < 24 | 7-10 min | Established; less sensitive for mild disease |
| SLUMS | 0-30 | < 27 (HS) / < 25 (no HS) | 7 min | Better MCI detection than MMSE |

- **Mini-Cog**: 3-item recall + clock drawing; takes 3 minutes; excellent for initial screening
- **Montreal Cognitive Assessment (MoCA)**: 30-point test; sensitive for MCI; score < 26 is abnormal
- **Mini-Mental State Examination (MMSE)**: 30-point test; less sensitive for early impairment; score < 24 suggests dementia
- **Saint Louis University Mental Status (SLUMS)**: 30-point test; better sensitivity than MMSE for MCI

### Functional Assessment

- **Activities of Daily Living (ADLs)**: bathing, dressing, toileting, transferring, eating
- **Instrumental Activities of Daily Living (IADLs)**: finances, medications, transportation, cooking, shopping
- Functional impairment in IADLs often precedes ADL decline and is key to distinguishing MCI from dementia

![Cognitive screening algorithm for primary care](images/cognitive-screening-algorithm.png)

## Diagnostic Workup

### Reversible Causes to Exclude

- **Medications**: anticholinergics, benzodiazepines, opioids, antihistamines
- **Metabolic**: hypothyroidism, vitamin B12 deficiency, folate deficiency, hepatic encephalopathy
- **Infections**: urinary tract infection, HIV, syphilis (in appropriate populations)
- **Structural**: normal pressure hydrocephalus (triad: gait apraxia, urinary incontinence, dementia), subdural hematoma
- **Psychiatric**: depression ("pseudodementia"), severe anxiety

### Standard Laboratory Workup

- **TSH**, **vitamin B12**, **comprehensive metabolic panel**
- Consider HIV, RPR, folate based on clinical context
- Urinalysis to exclude UTI as contributing factor in acute presentations

### Neuroimaging

- **Non-contrast CT or MRI of the brain**: recommended to exclude structural lesions
- MRI preferred for evaluating hippocampal atrophy, white matter disease, and vascular changes
- **Amyloid PET imaging** and **CSF biomarkers** (A-beta 42, phospho-tau) are increasingly used but typically reserved for specialist evaluation

![Dementia subtype differentiation by clinical features](images/dementia-subtypes.png)

## Pharmacologic Management

### Alzheimer Disease

- **Cholinesterase inhibitors** (donepezil, rivastigmine, galantamine): modest symptomatic benefit in mild-moderate disease
- **Memantine**: NMDA receptor antagonist for moderate-severe Alzheimer disease; may be combined with cholinesterase inhibitors
- **Anti-amyloid therapies** (lecanemab, donanemab): disease-modifying agents for early-stage Alzheimer disease with confirmed amyloid pathology; require ARIA monitoring with MRI
- Reassess benefit periodically; consider deprescribing in advanced disease

### Behavioral and Psychological Symptoms of Dementia (BPSD)

- **Non-pharmacologic interventions first**: structured routines, music therapy, caregiver education, environmental modification
- **Antipsychotics** (risperidone, quetiapine): reserved for severe agitation or psychosis unresponsive to non-pharmacologic measures; carry **FDA black box warning** for increased mortality
- **SSRIs** (citalopram, sertraline): may help with agitation and depression
- Avoid benzodiazepines and anticholinergics

## Non-Pharmacologic Management and Caregiver Support

- **Advance care planning**: discuss goals of care, health care proxy, and living will early
- **Driving assessment**: critical safety concern; refer for formal evaluation when indicated
- **Caregiver burden**: screen for depression and provide resources for respite care and support groups
- **Safety evaluation**: home safety assessment, medication management, wandering prevention
- Referral to **social work**, geriatrics, and community resources

![Comprehensive dementia management plan](images/dementia-management-plan.png)

## Key Clinical Pearls

- The Mini-Cog is a rapid, validated screening tool suitable for busy clinical settings.
- Always exclude reversible causes of cognitive impairment including medications, metabolic derangements, and depression.
- Functional assessment (ADLs/IADLs) is essential to distinguish MCI from dementia.
- Non-pharmacologic strategies should be the first-line approach for behavioral symptoms of dementia.
- Early advance care planning and caregiver support are as important as pharmacotherapy.

## References

1. Livingston G, Huntley J, Sommerlad A, et al. Dementia Prevention, Intervention, and Care: 2020 Report of the Lancet Commission. *The Lancet*. 2020;396(10248):413-446.
2. Nasreddine ZS, Phillips NA, Bedirian V, et al. The Montreal Cognitive Assessment, MoCA: A Brief Screening Tool for Mild Cognitive Impairment. *Journal of the American Geriatrics Society*. 2005;53(4):695-699.
3. Petersen RC, Lopez O, Armstrong MJ, et al. Practice Guideline Update: Mild Cognitive Impairment. *Neurology*. 2018;90(3):126-135.
4. van Dyck CH, Swanson CJ, Aisen P, et al. Lecanemab in Early Alzheimer's Disease. *New England Journal of Medicine*. 2023;388(1):9-21.