Diabetes tied to behavioural changes in patients with mild cognitive impairment

Persistent behavioural changes as an at-risk state for dementia appear to be relatively prevalent and associated with diabetes mellitus (DM) among individuals with mild cognitive impairment (MCI), according to a Singapore study.

The findings suggest that DM may be a risk factor for mild behavioural impairment (MBI) and that managing diabetes may be a potential therapeutic approach to improve clinical outcomes among MCI patients, said a team of researchers from the National Neuroscience Institute, Singapore.

“For some, MBI is the initial manifestation of dementia. The concept of MBI is informed by the notion that neuropsychiatric symptoms can be noncognitive markers of neurodegenerative disease and operationalizes it for more specific case detection in preclinical and prodromal disease states,” the team pointed out. [J Alzheimers Dis 2021;80:459-469; Alzheimers Dement 2020;16:192-199; Alzheimers Dement 2020;11:333-339; J Alzheimers Dis 2017;56:929-938]

Studying MBI in individuals at risk of dementia has major implications, as neuropsychiatric symptoms in MCI is prevalent (35–85 percent) and contribute to an increased risk of progression to dementia (10–25 percent). Additionally, MBI has been linked to detrimental effects, such as poor cognitive performance in older adults and increased caregiver burden. [J Alzheimers Dis 2009;18:11-30; Int Psychogeriatr 2021;33:285-293; BMC Geriatr 2020;20:510]

In the current study, the researchers looked at a real-world cohort of 93 individuals with MCI in a memory clinic and 79 community-dwelling adults with normal cognition (controls). All participants completed the MBI-checklist (MBI-C).

Compared with controls, MCI patients were older (69.08 vs 63.86 years), more likely to be men (51.6 percent vs 34.2 percent), and spent fewer years in education (10.44 vs 12.51 years). The MCI group also had a markedly greater prevalence of MBI (34.4 percent vs 20.3 percent; p=0.022) and higher mean MBI-C total score (7.01 vs 4.12; p=0.04). The highest- and lowest-rated subdomains among controls and MCI patients were impulse dyscontrol and abnormal thoughts and perception, respectively. [J Alzheimers Dis 2021;doi:10.3233/JAD-210037]

Notably, in the MCI group, significantly more patients with vs without DM had MBI (28.1 percent vs 10.4 percent; p=0.025). The interaction of DM and MCI was associated with much higher scores for the MBI-C total and subdomains of decreased motivation, emotional dysregulation, impulse dyscontrol, and abnormal thoughts and perception.

“Our prevalence estimates of MBI in both [the] MCI and control [group] were higher than the corresponding rates from the Spanish primary care samples,” the researchers noted. [Int Psychogeriatr 2019;31:231-239;  J Alzheimers Dis 2018;66:83-95]

While unclear, the underlying reason for why a Singapore MCI cohort had a higher prevalence of MBI than Caucasian populations may involve both modifiable (eg, cardiovascular risk factors) and nonmodifiable risk factors (eg, genetics), as the researchers pointed out.

“Differences in Singapore and Caucasian populations may also be related to cultural differences. For instance, apathy is reported to be more difficult to identify in Asian populations, and Asian populations are more likely to express psychological distress as physical complaints compared to Caucasian populations,” they added. [Alzheimer Dis Assoc Disord 2006;20:314-317; West J Med 2002;176:227-231]

The researchers highlighted the utility MBI-C as a tool to case-find MBI in cognitively normal and MCI populations, as well as the novelty of the association between DM and MBI psychoses and their potential in exploring prevention.