Short-Term Restriction of Physical and Social Activities Effects on Brain Structure and Connectivity

Abstract

Background: Prolonged confinement in enclosed environments has raised concerns about its effects on both physical and mental health. Although increased rates of depression or anxiety during COVID-19 lockdowns have been reported, the effects of short-term restrictions on social activities and physical on brain function and structure remain poorly known.

Methods: This study explored longitudinal changes in brain gray matter volume (GMV) and functional connectivity (FC) immediately after and four months following a short-term lockdown in comparison to pre-lockdown conditions. MRI data were collected from 20 participants before the lockdown, from 29 participants (14 original, 15 new) two months post-lockdown, and from 27 out of the 29 participants four months post-lifting of the lockdown.

Results: Results showed significant GMV reductions in the right gyrus rectus and cuneus post-lockdown, with further reductions observed four months after lifting the restrictions, affecting additional brain regions. Longitudinal FC trajectories revealed decreased connectivity between the default mode network (DMN) and sensorimotor/attention networks post-lockdown, and recovery after four months post-lifting of the lockdown.

Conclusions: The observed plasticity in brain FC indicates substantial recovery potential with the potential long-term effect of structural changes. Our findings offer insights into the effects of isolation on the human brain, potentially informing rehabilitation mechanisms and interventions for individuals in similar conditions.

Keywords: functional connectivity; lockdown environments; longitudinal study; resting-state fMRI; structural MRI.

Figure 1

Flowchart for participants’ scans. (i) A total of 20 healthy adults aged 18–27 were recruited, and MRI scans; (ii) three months later, participants were placed in a full lockdown environment. Right after lockdown, a total of 14 original participants and 15 new participants were enrolled for MRI scans and clinical assessments; and (iii) four months following the lifting of lockdown measures, 27 of the 29 participants underwent a third follow-up MRI scan and clinical assessment.

Figure 2

Group differences of gray matter volume. (A) Regions with significant differences in GMV between Scan1 and Scan2 (upper) and between Scan1 and Scan3 (paired t-test, p < 0.05, FDR correction). (B) Longitudinal alteration in the GMV in the right gyrus rectus between groups. There was a significant decrease in GMV in Scan2 and Scan3 compared to Scan1 (Scan1 > Scan2: p = 0.0001; Scan1 > Scan3: p = 0.004; paired t-test).

Figure 3

Group differences of functional connectivity. (A) Significantly decreased FC at Scan2 compared to Scan1 and significantly increased FC at Scan3 compared to Scan2. (B) The significant trajectories in the FC fit curves (p < 0.01, FDR-corrected). (C) These fit curves show that the FC decreased from pre-lockdown to right after lockdown and then increased from right after lockdown to post-lockdown. The color of the circle represents the 120 different regions from the Automatic Anatomical Labeling 2 (AAL2) atlas.

Figure 4

The correlation between longitudinally altered FC and mental status measurement scores. (A) The correlation between longitudinal changes in FC within the DMN and SMN and mental status measurement scores. (B) The correlation between longitudinal changes in FC within the DMN and ATN and mental status measurement scores. Partial correlation was used with controlling sex, age, and education of fMRI. The significance level was set at p < 0.05.