Abstract
Background:
Neuropsychological deficits, neuropsychiatric symptoms, and problems with instrumental activities of daily living are common in participants with mild cognitive impairment (MCI).
Objectives:
To assess how subtle to mildly impaired instrumental activities of daily living (IADLs) might be related to neuropsychological abilities (including executive control and episodic memory) and neuropsychiatric symptoms (including apathy and depression) among participants with a diagnosis of MCI.
Methods:
Participants were evaluated for MCI and possible dementia at an outpatient memory clinic on the basis of a comprehensive neuropsychological evaluation, a geriatric psychiatry evaluation, a magnetic resonance image of the brain, and serum studies to evaluate for a possible reversible cause of cognitive decline. A series of stepwise regression analyses were conducted whereby IADL ability was the dependent variable and neuropsychological abilities, such as executive control and episodic memory, or neuropsychiatric symptoms, including apathy and depression, were the independent or predictor variables. The presence and severity of neuropsychiatric symptoms was assessed using a modified version of the Neuropsychiatric Inventory (mNPI). Participants were grouped by MCI diagnosis status (amnestic MCI, combined dysexecutive/mixed MCI, and no MCI).
Results:
Twenty-six participants were in the amnestic MCI group, 19 in the combined dysexecutive/mixed MCI group, and 36 participants did not meet criteria for MCI (non-MCI group). Groups did not differ in age, education, Mini-Mental State Examination performance, IADL abilities, estimated premorbid general intellectual abilities, or mNPI ratings for apathy and depression. Stepwise regression analyses found a robust relationship between mild IADL impairment and greater apathy (R=0.497, r21,69=0.247, P<.001; β=−0.497, P<.001). Depression did not enter the final model. A weaker—but statistically significant—relationship was found between mild IADL impairment and worse executive control test performance (R=0.271, r21,68=0.073, P<.023; β=0.271, P<.23). Episodic memory did not enter the final model. When both apathy and executive control were assessed as related to IADL impairment, only apathy entered the final model (R=0.497, R21,69=0.247, P<.001; β=−0.497, P<.001).
Conclusion:
Mildly impaired IADL functioning can negatively affect quality of life. Moreover, apathy may be amenable to treatment. In a primary geriatric care setting, neuropsychiatric symptoms and neuropsychological abilities should be routinely assessed.
Mild cognitive impairment (MCI) is believed to be a prodrome that eventually leads to the emergence of dementia.
1 There is considerable research documenting the neuropsychological parameters associated with MCI.
2,3 Patients with MCI also present with a wide number of neuropsychiatric symptoms,
4 including depression and apathy.
5,6 Moreover, neuropsychiatric problems such as depression and apathy have been shown to be risk factors for the eventual conversion of MCI to dementia.
7,8
Patients with MCI also present with measurable difficulty performing instrumental activities of daily living (IADLs).
9,10 Among patients with MCI, impairment involving neuropsychological abilities, such as executive control and episodic memory, as well as neuropsychiatric symptoms, such as depression and apathy, have been linked to eventual conversion to dementia.
11-14 Rog et al
15 examined performance on tests assessing executive control, episodic memory, neuropsychiatric symptoms, and everyday functions as assessed using the Everyday Cognition scales
13 in patients with dementia and MCI. They found a greater association between everyday functioning/IADL impairment and depression and apathy compared with executive control and episodic memory test performance. However, the external validity of this study
15 was limited by the use of the Spanish and English Neuropsychological Assessment Scales, which is not widely used. Moreover, this assessment of episodic memory does not include an assessment of delay recognition—a parameter often used to characterize the severity of amnesia in patients with MCI and dementia.
In the current study, a comprehensive and more traditional neuropsychological protocol was administered to participants suspected of having MCI. The presence of apathy and depression was assessed using a modified version of the Neuropsychiatric Inventory (mNPI).
16,17 We sought to examine the relative contribution of both neuropsychological abilities (ie, executive control and episodic memory) vs neuropsychiatric symptoms (ie, apathy and depression) as related to IADL difficulty.
Participants were recruited between February 2016 and September 2017 on the basis of their referral for an evaluation for a putative dementia disorder to the New Jersey Institute for Successful Aging at Rowan University as part of the Memory Assessment Program.
All participants underwent a comprehensive neuropsychological evaluation and were also examined by a social worker and a board-certified geriatric psychiatrist. Serum blood cell tests included a basic metabolic panel, liver function, rapid plasma reagin, and complete blood cell count, which measured levels of thyroid-stimulating hormone, vitamin B12, and folate, were obtained to evaluate for reversible causes of dementia. Participants also underwent magnetic resonance imaging of the brain using either a 1.5- or 3.0-Tesla Siemens magnetic scanner. T1-weighted spoiled gradient echo (repetition time [TR] 2300 milliseconds, echo time [TE] 1.87 milliseconds), T2-weighted (TR 5500 milliseconds, TE 114 milliseconds), fluid-attenuated inversion recovery (TR 9000 milliseconds, TE 100 milliseconds), and susceptibility weighted (TR 27 milliseconds, TE 20 milliseconds) imaging sequences studies were obtained.
After all investigations were obtained, a clinical diagnosis for the presence of dementia or MCI
1 was determined at an interdisciplinary team conference. Inclusion criteria included history from participants and a knowledgeable family member to suggest insidious onset of neurocognitive decline. Participants were excluded if they had a history of head injury, substance abuse, or major neuropsychiatric disorders (eg, major depressive disorder, epilepsy) or deficiencies in vitamin B
12, folate, or thyroid-stimulating hormone. A knowledgeable family member for each participant provided information regarding functional status.
This study was approved by the Rowan University Institutional Review Board with informed consent obtained consistent with the Declaration of Helsinki.
A total of 77 participants were available for data analysis. On the basis of the criteria described above, 26 participants received a diagnosis of aMCI, 4 received a diagnosis of dysMCI, and 15 received a diagnosis of mxMCI. Because of the small number of participants with dysMCI, a combined dysexecutive/mixed (dys/mx) MCI subgroup (n=19) was constructed. An additional 36 participants who presented for clinical evaluation did not meet criteria for MCI (non-MCI group). The 3 groups of MCI participants did not differ based on age, education, or IADL ability. There were also no between-group differences in total mNPI score or mNPI ratings of depression and apathy (
Table) or in gross level of cognitive functioning, depression (as assessed with the Geriatric Depression Scales), or projected premorbid general intellectual functions.
Table.
Demographic Information, Neuropsychiatric Symptoms, and Neuropsychological Performance
| Group, Mean (SD) |
Measure | non-MCI | aMCI | dys/mxMCI |
Demographics | | | |
Age, y | 76.91 (6.41) | 74.81 (7.02) | 77.84 (5.31) |
Education, y | 14.44 (3.03) | 14.81 (2.64) | 13.52 (2.87) |
Clinical Findings | | | |
MMSE (range, 0-30) | 27.72 (1.68) | 26.59 (2.34) | 26.63 (1.73) |
GDS (range, 0-30) | 3.33 (2.61) | 3.09 (2.44) | 4.11 (3.02) |
IADL scale (range, 0-17) | 14.93 (2.35) | 13.95 (3.05) | 14.23 (2.70) |
Neuropsychiatric Symptoms | | | |
mNPI, apathy (range, 0-12) | 1.01 (1.43) | 1.83 (2.96) | 0.95 (1.49) |
mNPI, depression (range, 0-12) | 1.29 (1.58) | 1.17 (1.84) | 0.80 (1.49) |
Neuropsychological Tests, z score | | | |
WRAT4 Readinga | 114.94 (18.38) | 116.72 (13.48) | 109.89 (16.23) |
Trail Making Test–Part Bb | −0.16 (0.81) | −0.34 (0.91) | −0.62 (0.87) |
Letter fluencyb | −0.12 (0.86) | −0.65 (0.96) | −1.30 (0.86) |
CVLT-SF delay free recallb | −0.33 (1.01) | −1.81 (0.58) | −0.88 (1.14) |
CVLT-SF delay recognitionb | 0.22 (0.83) | −1.43 (0.76) | −0.36 (0.95) |
Table.
Demographic Information, Neuropsychiatric Symptoms, and Neuropsychological Performance
| Group, Mean (SD) |
Measure | non-MCI | aMCI | dys/mxMCI |
Demographics | | | |
Age, y | 76.91 (6.41) | 74.81 (7.02) | 77.84 (5.31) |
Education, y | 14.44 (3.03) | 14.81 (2.64) | 13.52 (2.87) |
Clinical Findings | | | |
MMSE (range, 0-30) | 27.72 (1.68) | 26.59 (2.34) | 26.63 (1.73) |
GDS (range, 0-30) | 3.33 (2.61) | 3.09 (2.44) | 4.11 (3.02) |
IADL scale (range, 0-17) | 14.93 (2.35) | 13.95 (3.05) | 14.23 (2.70) |
Neuropsychiatric Symptoms | | | |
mNPI, apathy (range, 0-12) | 1.01 (1.43) | 1.83 (2.96) | 0.95 (1.49) |
mNPI, depression (range, 0-12) | 1.29 (1.58) | 1.17 (1.84) | 0.80 (1.49) |
Neuropsychological Tests, z score | | | |
WRAT4 Readinga | 114.94 (18.38) | 116.72 (13.48) | 109.89 (16.23) |
Trail Making Test–Part Bb | −0.16 (0.81) | −0.34 (0.91) | −0.62 (0.87) |
Letter fluencyb | −0.12 (0.86) | −0.65 (0.96) | −1.30 (0.86) |
CVLT-SF delay free recallb | −0.33 (1.01) | −1.81 (0.58) | −0.88 (1.14) |
CVLT-SF delay recognitionb | 0.22 (0.83) | −1.43 (0.76) | −0.36 (0.95) |
×
Stepwise linear and multiple regression analyses examining the relationship between IADL and neuropsychiatric symptoms was significant, with only apathy entering the final model (R=0.497, r21,69=0.247, P<.001; β=−0.497, P<.001) such that a lower (ie, more impaired) IADL ability was associated with greater apathy. Depression did not enter the final model. Stepwise linear and multiple regression analyses examining IADL abilities and executive test performance were also significant (R=0.271, r21,68=0.073, P<.023; β=0.271, P<.023), with lower IADL ability associated with worse Trail Making Test–Part B test performance. Letter fluency did not enter the final model. A similar regression analysis demonstrated no association between IADL abilities and episodic memory. A final multiple regression analysis of caregiver mNPI rating of apathy and Trail Making Test–Part B performance as related to IADL functioning was significant (R=0.497, R21,69= 0.247, P<.001, β=−0.497, P<.001). Only apathy entered the final model such that lower IADL ability was associated with higher caregiving ratings for apathy. These analyses were also conducted for only participants with MCI, and the results were unchanged.