Caregiver Reports of Lucid Episodes in Alzheimer’s Dementia and Lewy Body Dementias

Introduction

Alzheimer’s Dementia (AD) and Lewy Body Dementias (LBD)—which include dementia with Lewy bodies (DLB) and Parkinson disease dementia (PDD)—are the most common causes of neurodegenerative dementia, accounting for 60-80% and 20-30% of all dementia cases, respectively. Over 8.1 million people have AD and LBD, and they receive care from 11.5 million family caregivers in the U.S.^1,2 While AD and LBD share some clinical symptoms, research has also focused on their clinical differentiation in order to inform diagnosis, treatment, and care planning.^3-5

In contrast to the routine cognitive fluctuations that are expected among people living with dementia (PLWD), ⁶ lucid episodes are periods when there is a transient recovery of communication or other abilities that had seemingly been permanently lost.^7,8 Lucid episodes provide brief but meaningful windows of connection, but their existence conflicts with fundamental assumptions about the downward and permanent trajectory of cognition that typically defines dementia. ⁹ Occurring during the later course of disease progression, they are often described as diverse in presentation. They are sometimes prompted by external stimuli but can also occur spontaneously.^10-14 No studies, however, have compared lucid episodes between different dementia types, including AD and LBD, and it is unclear if, like their differing clinical presentations and symptoms, lucid episodes by type of dementia also differ. Characterizing the frequency, duration, and intensity of lucid episodes across AD and LBD, including changes in awareness and communication as reported by family caregivers, is a critical first step towards understanding if lucid episodes are shaped by disease specific pathology. This study analyzes AD and LBD family caregiver reports of lucid episodes to understand these differences and their implications for diagnosis and care.

Methods

Results

Caregiver and PLWD Characteristics in AD and LBD Caregivers

The sample included AD caregivers (n = 191) and LBD caregivers (n = 21; see Table 1). AD caregivers were 74% female, 83% white, 78% married, and had a mean age of 65 years. Nearly half of AD caregivers (45%) were the spouse or partner to the PLWD and 46% were adult children or children-in-law of the PLWD. On average, AD caregivers had been providing care for 6.9 years. LBD caregivers were 81% female, 91% white, 86% married and had a mean age of 65 years. Over half of LBD caregivers (57%) were the spouse or partner of the PLWD. On average, LBD caregivers had been providing care for 5.4 years. All variables except for one showed no significant differences between AD and LBD caregivers: LBD caregivers reported more hours of care during weekdays than AD caregivers (t = −2.11, p = .036; d = 0.48). This represents a medium effect size, ²³ confirming a meaningful difference in caregiving burden between the two groups.

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Table 1.

Comparisons of Sample Characteristics Between AD and LBD Caregivers

Variables	AD		LBD		t or χ2	Effect size	[95% CI]
	M	(SD)	M	(SD)
Caregiver characteristics
Relation to PLWD, %
Spouse or partner	45.0		57.1		1.12	0.07	[0.01, 0.21]
Child or child-in-law	45.5		38.1		0.43	0.05	[0.00, 0.17]
Age	64.72	(12.06)	64.90	(12.44)	−0.07	0.02	[−0.44, 0.47]
Female, %	73.8		81.0		0.46	0.05	[0.00, 0.16]
Married, %	78.0		85.7		0.67	0.06	[0.00, 0.17]
Employed, %	39.3		28.6		0.95	0.07	[0.00, 0.19]
Education a	5.15	(1.31)	5.43	(0.98)	−0.94	0.22	[−0.24, 0.67]
Financial situation b	3.41	(0.84)	3.57	(0.68)	−0.83	0.19	[−0.26, 0.64]
Non-Hispanic white, %	83.2		90.5		0.59	0.05	[0.00, 0.15]
Self-rated health c	3.57	(0.84)	3.48	(0.87)	0.46	0.11	[−0.34, 0.56]
PLWD characteristics
Age	79.39	(9.65)	78.62	(9.38)	0.35	0.08	[−0.37, 0.53]
Female, %	62.8		42.9		3.17	0.12	[0.01, 0.27]
Married, %	61.8		76.2		1.69	0.09	[0.01, 0.21]
Education a	4.10	(1.75)	4.05	(1.47)	0.12	0.03	[−0.42, 0.48]
Non-Hispanic white, %	84.8		95.2		1.48	0.08	[0.01, 0.15]
Caregiving characteristics
Duration of care (in months)	82.71	(64.97)	64.86	(45.27)	1.23	0.28	[−0.17, 0.73]
Coresiding with PLWD, %	55.0		66.7		1.05	0.07	[0.01, 0.19]
PLWD limitations in ADL d	1.52	(0.97)	1.70	(0.79)	−0.83	0.19	[−0.26, 0.64]
PLWD limitations in IADL e	2.67	(0.46)	2.75	(0.34)	−0.78	0.18	[−0.27, 0.63]
Hours of care (per day)
Weekday	8.53	(7.46)	12.19	(8.52)	−2.11*	0.48	[0.03, 0.94]
Weekend	10.02	(8.20)	13.38	(8.81)	−1.77	0.41	[−0.05, 0.86]
Social support f	3.19	(1.13)	2.90	(1.13)	1.11	0.25	[−0.20, 0.71]

Note. Participant N = 212 (AD caregiver n = 191; LBD caregiver n = 21). PLWD = person living with dementia; AD = Alzheimer’s disease; LBD = Lewy Body Dementias; ADL = activities of daily living; IADL = instrumental activities of daily living.

Effect sizes were calculated using Cohen’s d for continuous variables and Cramér’s V for categorical variables. To account for imbalanced sample sizes, 95% bias-corrected and accelerated (BCa) confidence intervals were estimated using bootstrapping with 1,000 resamples.

*p < .05.

^a1 = some primary or high school to 7 = doctoral degree.

^b1 = having difficulty paying bills to 4 = after paying bills, still enough money.

^c1 = poor to 5 = excellent.

^dMean of 5 items rated from 0 = normal/no difficulty to 3 = completely dependent on someone to help.

^eMean of 10 items rated from 0 = normal/no difficulty to 3 = completely dependent on someone to help.

^fMean of 8 items rated from 1 = none of the time to 5 = all of the time.

Comparisons of Lucid Episodes Between AD and LBD Caregivers

Descriptions of lucid episodes witnessed by AD and LBD caregivers within the past month are presented in Table 2. To test group differences, odds ratios (OR) or unstandardized coefficients (B) were estimated using GEE, accompanied by 95% bias-corrected and accelerated (BCa) confidence intervals. AD caregivers were more likely to report that the PLWD was awake but non-responsive prior to a lucid episode (12.2% vs. 0.0%; χ² = 9.01, p = .003). Regarding the circumstances preceding these episodes, LBD caregivers were more likely to report a change in medication (OR = 2.59, p = .080, 95% CI [0.89, 7.50]). Additionally, LBD caregivers reported that lucid episodes were more likely to occur without a prompt from another person (OR = 2.20, p = .034, 95% CI [1.06, 4.56]). Compared to AD caregivers, LBD caregivers observed lucid episodes characterized by a greater magnitude of change in both awareness (B = 0.71, p < .001; d = 0.71) and communication ability (B = 0.60, p < .001; d = 0.64). Furthermore, lucid episodes witnessed by LBD caregivers lasted longer (B = 0.61, p = .066; d = 0.38) and were more likely to occur before noon (OR = 2.37, p = .024, 95% CI [1.12, 5.00]).

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Table 2.

Comparisons of Lucid Episodes Between AD and LBD Caregivers

Variables	AD		LBD		OR or B	[95% CI]
	M	(SD)	M	(SD)
Cognition prior to LE, %
Fully aware	1.0		0.0		—	—
Minor difficulty	8.4		6.1		0.92	[0.27, 3.11]
Moderate difficulty	43.2		48.5		1.28	[0.57, 2.90]
Extreme difficulty	30.8		40.9		1.43	[0.61, 3.37]
Awake, but not responding or reacting	12.2		0.0		—	—
Mostly asleep, not aware of surroundings	4.5		4.5		0.99	[0.12, 8.06]
Unconscious	0.0		0.0		—	—
Circumstances prior to LE, %
No special circumstances	44.4		40.3		0.81	[0.40, 1.61]
Visits from family/friends	23.4		35.8		1.79	[0.85, 3.80]
Change in medication	3.9		10.4		2.59†	[0.89, 7.50]
Change in healthcare setting	2.4		3.0		1.26	[0.30, 5.25]
Music playing	16.0		10.4		0.45	[0.11, 1.94]
Reminiscing	11.9		13.4		1.08	[0.35, 3.35]
Valued ritual/behaviors	8.2		14.9		1.94	[0.63, 5.99]
How LE started, %
Someone prompted	35.6		25.0		0.57	[0.25, 1.26]
Without a prompt from another person	45.9		60.9		2.20*	[1.06, 4.56]
After a prompt (eg, a song, prayer)	16.6		14.1		0.65	[0.19, 2.17]
Degree of change during LE a
In awareness	2.26	(1.02)	2.99	(0.77)	0.71***	[0.39, 1.02]
In communication ability	2.00	(0.95)	2.67	(0.81)	0.60***	[0.25, 0.95]
How long LE lasted b	2.22	(1.60)	2.84	(1.69)	0.61†	[-0.04, 1.25]
Time of the day LE occurred, %
Morning (5 a.m. to 12 p.m.)	29.3		50.8		2.37*	[1.12, 5.00]
Afternoon (12 p.m. to 6 p.m.)	54.7		42.4		0.64	[0.32, 1.29]
Evening/night (6 p.m. to 5 a.m.)	16.0		6.8		0.42	[0.14, 1.23]
Best description of LE, %
Aware, communication made complete sense	49.5		51.5		1.06	[0.49, 2.27]
Aware, communication made some sense	36.5		40.9		1.29	[0.61, 2.75]
Aware, but not make any sense	6.8		7.6		1.13	[0.21, 6.12]
Aware, but only non-verbal communication	6.3		0.0		—	—
Drowsy, confused, not make any sense	0.9		0.0		—	—
PLWD knew about their change in LE, %	9.2		31.8		4.39**	[1.72, 11.20]

Note. Episode N = 653 (AD caregiver n = 586; LBD caregiver n = 67). AD = Alzheimer’s disease; LBD = Lewy Body Dementias; LE = lucid episode; PLWD = person living with dementia.

For tests of group differences, odds ratios (OR) for categorical variables and unstandardized coefficients (B) for continuous variables were estimated using Generalized Estimating Equations (GEE); LBD was coded as 1, with AD (coded as 0) serving as the reference group.

†p < .10. *p < .05. **p < .01. ***p < .001.

^a1 = very small change to 5 = very large change.

^b1 = under 10 minutes to 8 = more than 7 days.

While most lucid episodes contained communication that was coherent, AD caregivers more frequently reported episodes involving only non-verbal awareness without verbal communication (6.3% vs. 0.0%; χ² = 4.43; p = .035). Finally, LBD caregivers were more likely to report that the PLWD exhibited meta-awareness, or knowledge of their own change in lucidity (OR = 4.39, p = .002, 95% CI [1.72, 11.20]).

Discussion

The current study aimed to describe differences in reports of lucid episodes from family caregivers of people living with AD and LBD. The specific pathology causing each type of dementia dictates the differences in behavioral trajectories and pharmacological risks experienced by the PLWD ²⁴ and the unique care burden for family caregivers. ²⁵ Clinical presentations are different in AD and LBD. ³ Based on our current scientific understanding, while AD typically presents with progressive episodic memory loss, language deficits, and communication difficulties, and motor symptoms can be rare until late stages. LBD, on the other hand, is characterized by fluctuating cognition and neuroleptic sensitivity; and the clinical presentation could include parkinsonism. ⁵ Our findings suggest that, just as there are unique clinical presentations and associated symptoms between AD and LBD, lucid experiences may also be different. For example, AD caregivers reported more non-responsiveness prior to lucid episodes than LBD caregivers. LBD caregivers, however, reported more medication changes prior to lucid episodes and episodes characterized by a greater magnitude of change in awareness and communication ability than AD caregivers. These presentations by dementia type may be especially helpful in distinguishing routine “good days and bad days” or typical symptoms from the unexpected and transient recovery of abilities characterizing lucidity and could provide guidance for future research to explore antecedents to lucidity and the possible neurological pathways that can result in lucidity.

AD and LBD caregivers reported lucid episodes with similar frequency and descriptions. Lucid episodes differed in intensity, as LBD caregivers reported greater changes in awareness and communication ability compared to AD caregivers. Particularly, LBD caregivers were more likely to report on PLWD’s meta-awareness about their change in lucidity, which raises the possibility that meta-awareness could be an attribute of lucid episodes in LBD and that aspects of self and self-awareness may persist throughout the LBD trajectory,^10,26 though this interpretation requires further exploration. This finding aligns with the concept of preserved consciousness, or the idea that many aspects of memory, cognition, emotion, and perception are preserved among PLWD. ²⁷ Exploration of meta-awareness in LBD, including its changes over time, may help disentangle the mechanisms underlying awareness ²⁸ and help to determine if awareness is an attribute or indicator of lucidity for LBD.^9,14,26

LBD caregivers reported more lucid episodes occurring in the morning and they lasted longer than episodes reported by AD caregivers. It is possible that lucid episodes in LBD are associated with sleep disturbances including excessive daytime sleepiness, and rapid eye movement behavior disorder which are present in 90% of people with LBD. ²⁹ The finding that lucid episodes were reported to be more frequently in the morning hours may be an indication that lucidity occurs temporarily upon waking and before daytime sleepiness sets in, but further research is needed. These preliminary findings raise the possibility that interventions targeting sleep regulation may enhance lucid episodes by optimizing alertness and mood in the morning hours. The longer duration of lucid episodes in LBD may also provide opportunities for other forms of data capture about lucidity, such as video or ecological momentary assessments, instead of solely relying on caregiver reports. Other forms of data may provide nuanced details about lucidity that could help develop interventions to support caregivers witnessing lucidity and offer them actionable feedback on the experience, given that some caregivers find lucid episodes stressful.^30,31 Future research should integrate these approaches to capture the flow and awareness of attention of lucid episodes in real-time.

Our results suggest that the type of dementia influences the intensity, timing, and presence of meta-awareness experienced during lucid episodes. Given the observational and retrospective nature of the data and the small LBD caregiver sample, these exploratory findings should be interpreted with appropriate caution pending replication in larger, prospectively designed studies. Further research with larger, more diverse caregiver samples is needed to validate these results and provide a clearer understanding of lucid episodes across dementia types. While some PLWD may have had biomarker confirmed diagnosis, the diagnoses were not clinically verified, but rather reported by caregivers, and therefore, there may be some misclassification of dementia type. Additionally, while caregivers were provided with practical guidelines to identify and report lucid episodes, caregiver reports of lucidity may reflect cultural interpretations or emotional perceptions of the experience. Finally, our study relied on caregiver’s retrospective accounts over a 30-day period, which introduces potential bias. Future studies should assess lucid episodes in real-time and may offer more precise insights into the nature and dynamics of lucid episodes.

Despite these limitations, our study reveals novel findings on how LBD and AD caregivers experience and report lucid episodes. These results can help guide caregiver education, inform future hypotheses on neurological pathways for lucid episodes, and provide clinical guidelines on how best to support caregivers.