To assess the clinical correlates of frontotemporal asymmetry and dorsal/ventral predominance of atrophy in patients with behavioral variant frontotemporal dementia (bvFTD).

Regional brain atrophy has been associated with the presence and severity of neuropsychiatric symptoms, such as apathy and disinhibition, in patients with bvFTD. Atrophy in bvFTD can be symmetric or asymmetric, with each side potentially displaying a range of atrophy from minimal to severe. Little is known about how the degree of structural asymmetry affects bvFTD clinical symptomatology.

Symptom severity was assessed in 250 bvFTD patients (151 men and 99 women) aged 29 – 83 (M = 61.43; SD = 8.82) by the Neuropsychiatric Inventory (NPI). Atrophy maps were calculated for all patients. Asymmetry Index (AI) was calculated as the difference between mean atrophy in the right and left frontotemporal regions. Dorsality Index (DI) was calculated as the difference between atrophy in dorsal and ventral frontotemporal regions. We investigated the relationship between the indices and neuropsychiatric symptoms. Analyses were controlled for age, sex, total intracranial volume, Clinical Dementia Rating sum-of-boxes, and scanner type.

The distribution of Asymmetry Index scores revealed that most patients displayed symmetric frontotemporal atrophy, with a minority exhibiting right or left-predominant asymmetry. DI revealed a greater proportion of patients demonstrated ventral-predominant atrophy. Patients with more right-lateralized atrophy on the Asymmetry Index displayed higher scores on NPI eating behavior and hallucination subscales (p < .05). Ventral-predominance on the Dorsality Index was related to higher scores on Anxiety, Euphoria, and Disinhibition subscales (p < .05).

We identified relationships between both structural asymmetry and ventral/dorsal predominance of atrophy and the severity of neuropsychiatric symptoms. In addition to the important association between regional atrophy and type of behavior change, the degree of structural asymmetry also plays a role in understanding the altered behavior in bvFTD patients.