Hippocampal volume and cognitive performance in long-standing Type 1 diabetic patients without macrovascular complications.

AIMS: Hippocampal atrophy and memory deficits have been reported in Type 2 diabetes. Whether similar alterations occur in Type 1 diabetes is currently unknown.

METHODS: In a case-control design, 13 Type 1 diabetic patients with at least 10 years' duration of disease, but free from clinical signs of macrovascular disease, were compared with age- and gender-matched control subjects. Hippocampal volume and measures of global cerebral cerebrospinal fluid (CSF) were determined from magnetic resonance imaging (MRI) scans. Cognitive functions were assessed using four neuropsychological tests. Mood and depression were measured by questionnaires.

RESULTS: Hippocampal volume and memory did not differ between Type 1 diabetic patients and control subjects. However, a significantly increased amount of cerebral CSF suggestive of mild cerebral atrophy was observed in the patients. In addition, deficits in psychomotor speed and selective attention were apparent. Eleven of 13 patients had retinopathy and/or nephropathy. Findings were unrelated to cerebrovascular disease, white matter disease or silent strokes.

CONCLUSIONS: Results from our small study in Type 1 diabetic patients do not support findings from previous studies of Type 2 diabetic patients demonstrating reductions in hippocampal volume and impaired memory. On the contrary, we observed evidence for mild cerebral atrophy and impaired psychomotor speed and selective attention. This is in line with some previous studies in Type 1 diabetes. If replicated in larger studies, our findings would support the idea that the effects on brain function and structure differ between Type 1 and Type 2 diabetes.